{"id":2359,"date":"2015-07-23T11:28:39","date_gmt":"2015-07-23T18:28:39","guid":{"rendered":"http:\/\/physikon.net\/?page_id=2359"},"modified":"2023-09-20T16:07:56","modified_gmt":"2023-09-20T23:07:56","slug":"application-to-specific-compounds","status":"publish","type":"page","link":"http:\/\/physikon.net\/?page_id=2359","title":{"rendered":"Notes\/calculations specific to each compound"},"content":{"rendered":"<hr \/>\n<p><a href=\"#y123_90\" name=\"Y123_90\"><\/a><\/p>\n<hr \/>\n<p><strong>YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub><\/strong> (<em>Pmmm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 93.78 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/REBa2Cu3O7-d.gif\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2173 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/REBa2Cu3O7-d.gif\" alt=\"REBa2Cu3O7-d\" width=\"176\" height=\"290\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">To determine \u03c3<sub>0<\/sub>, one considers oxygen content <em>x<\/em> above the minimum value (<em>x<\/em><sub>0<\/sub> = 6.35 [1]) required for superconductivity to occur. \u00a0The total oxygen content associated with the optimal superconductive state is then, (6.92 \u2013 6.35) = 0.57. \u00a0Given a valence of \u20132 per oxygen ion, the total number of carriers available to dope the superconducting structure is 2\u00d70.57 = 1.14. \u00a0As there are five oxygen-containing layers, two CuO<sub>2<\/sub> layers, two BaO layers and one CuO layer, and assuming that all five layers are populated equally, one then has [1]:<\/p>\n<ul>\n<li style=\"text-align: justify;\">Type I reservoir: BaO-CuO-BaO<\/li>\n<li style=\"text-align: justify;\">Type II reservoir: CuO<sub>2<\/sub>-Y-CuO<sub>2<\/sub><\/li>\n<li style=\"text-align: justify;\">\u03c3 =\u00a0\u03c3<sub>0<\/sub> = 1.14\/5 = 0.228<\/li>\n<li style=\"text-align: justify;\">\u03b7 = 2;\u00a0\u03bd = 2<\/li>\n<li style=\"text-align: justify;\"><em>A<\/em> = 14.8596 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 2.2677 \u00c5<\/li>\n<li style=\"text-align: justify;\">T<sub>C0<\/sub><sup>calc<\/sup> = 93.36 K<\/li>\n<\/ul>\n<ol>\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#y123_60\" name=\"Y123_60\"><\/a><\/p>\n<hr \/>\n<p><strong>YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.60<\/sub><\/strong> (<em>Pmmm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 63 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/REBa2Cu3O7-d.gif\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2173 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/REBa2Cu3O7-d.gif\" alt=\"REBa2Cu3O7-d\" width=\"176\" height=\"290\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">Using rule (2b), \u03c3 for the &#8220;60 K&#8221; phase material can be similarly obtained as with the &#8220;90 K&#8221; material, but with a participating charge of 2(6.60 \u2013 6.35)\/5 = 0.1. However, one obtains the same answer by simply scaling the oxygen (anion) content above x<sub>0<\/sub> = 6.35 relative to that of YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>. \u00a0Therefore, one has [1]:<\/p>\n<ul>\n<li style=\"text-align: justify;\">Type I reservoir: BaO-CuO-BaO<\/li>\n<li style=\"text-align: justify;\">Type II reservoir: CuO<sub>2<\/sub>-Y-CuO<sub>2<\/sub><\/li>\n<li style=\"text-align: justify;\">\u03c3 = [(6.60\u00a0\u2013 6.35)\/(6.92\u00a0\u2013 6.35)]\u00a0\u03c3<sub>0<\/sub> = 0.439 \u03c3<sub>0<\/sub> = 0.1<\/li>\n<li style=\"text-align: justify;\">\u03b7 = 2;\u00a0\u03bd = 2<\/li>\n<li style=\"text-align: justify;\"><em>A<\/em> = 14.8990 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 2.2324 \u00c5<\/li>\n<li style=\"text-align: justify;\">T<sub>C0<\/sub><sup>calc<\/sup> = 64.77 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#La123\" name=\"La123\"><\/a><\/p>\n<hr \/>\n<p><strong>LaBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>7\u2013\u03b4<\/sub><\/strong> (<em>Pmmm<\/em>,\u00a0T<sub>C0<\/sub><sup>meas<\/sup> = 97 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/REBa2Cu3O7-d.gif\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2173 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/REBa2Cu3O7-d.gif\" alt=\"REBa2Cu3O7-d\" width=\"176\" height=\"290\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">For this material, the valences and stoichiomentries are unchanged with respect to YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>, such that\u00a0\u03b3 = 1. \u00a0Therefore, the optimal transition temperature for this and all other REBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>7\u2013\u03b4<\/sub>\u00a0compounds is completely determined by the structural parameters, <em>A<\/em> and \u03b6 [1]:<\/p>\n<ul>\n<li>Type I reservoir: BaO-CuO-BaO<\/li>\n<li>Type II reservoir: CuO<sub>2<\/sub>-Y-CuO<sub>2<\/sub><\/li>\n<li>\u03c3 =\u00a0\u03c3<sub>0<\/sub><\/li>\n<li>\u03b7 = 2;\u00a0\u03bd = 2<\/li>\n<li><em>A<\/em> = 15.3306 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 2.1952 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 98.00 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#ChrgComp123\" name=\"ChrgComp123\"><\/a><\/p>\n<hr \/>\n<p><strong>(Ca<sub>0.45<\/sub>La<sub>0.55<\/sub>)(Ba<sub>1.3<\/sub>La<sub>0.7<\/sub>)Cu<sub>3<\/sub>O<sub>y<\/sub><\/strong> (<em>Pmmm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 80.5 K)<img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2173 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/REBa2Cu3O7-d.gif\" alt=\"REBa2Cu3O7-d\" width=\"176\" height=\"290\" \/><\/p>\n<p style=\"text-align: justify;\">The charge compensated compound, (Ca<sub>x<\/sub>La<sub>1\u2013x<\/sub>)(Ba<sub>1.75\u2013x<\/sub>La<sub>0.25+x<\/sub>)Cu<sub>3<\/sub>O<sub>y<\/sub>\u00a0(or CLBLCO), optimizes for x = 0.45. \u00a0To determine \u03b3, one considers only the type I reservoir and its stoichiometric relationship to that of YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>. \u00a0From rule (2b) \u03b3 is defined by the ratio of the Ba content of CLBLCO (i.e., 1.75\u00a0\u2013 x) divided by the 2 Ba ions contained in YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>. \u00a0Thus, one obtains [1]:<\/p>\n<ul>\n<li>Type I reservoir: 1\/2(Ba<sub>1.3<\/sub>La<sub>0.7<\/sub>)O-CuO-1\/2(Ba<sub>1.3<\/sub>La<sub>0.7<\/sub>)O<\/li>\n<li>Type II reservoir: CuO<sub>2<\/sub>-(Ca<sub>0.45<\/sub>La<sub>0.55<\/sub>)-CuO<sub>2<\/sub><\/li>\n<li>\u03c3 = [(1.75 \u2013 0.45)\/2]\u00a0\u03c3<sub>0<\/sub> = 0.65 \u03c3<sub>0<\/sub><\/li>\n<li>\u03b7 = 2;\u00a0\u03bd=2<\/li>\n<li><em>A<\/em> = 15.0118 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 2.1297 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 82.29 K<\/li>\n<\/ul>\n<p style=\"text-align: justify;\"><em>Verifying Eq. (2.3) of Ref. [2]\u00a0<\/em>\u2013 The equilibrium assertion of equation, \u03bd\u03c3<sub>I<\/sub> = \u03b7\u03c3<sub>II<\/sub>, defines the requirement for achieving an optimal high-<em>T<\/em><sub>C<\/sub> superconducting state.\u00a0 It is, therefore, important that its validity be tested.\u00a0 An ideal material for this exercise is the charge-compensated compound (Ca<sub>x<\/sub>La<sub>01\u2013x<\/sub>)(Ba<sub>1.75\u2013x<\/sub>La<sub>0.25+x<\/sub>)Cu<sub>3<\/sub>O<sub>y<\/sub>, for which the doping parameters for La and O are well established [1].\u00a0Accepting that the La<sup>+3<\/sup> substituting for Ba<sup>+2<\/sup> and the excess oxygen are associated with the type I reservoir and Ca<sup>+2<\/sup> substituting for La<sup>+3<\/sup> is associated with the type II reservoir, one can write,<\/p>\n<p style=\"text-align: justify;\">\u03bd\u03c3<sub>I <\/sub>=\u03b7\u03c3<sub>II<\/sub>\u00a0 \u2192\u00a0 \u03bd(\u03b3<sub>Ba\/La<\/sub>) (\u03b3<sub>O<\/sub>) \u03c3<sub>0<\/sub> = \u03b7(\u03b3<sub>La\/Ca<\/sub>) \u03c3<sub>0<\/sub> ,<\/p>\n<p style=\"text-align: justify;\">where, in this case,\u00a0\u03bd = \u03b7 = 2.\u00a0 The three \u03b3-factors derive from the valence scaling rules as follows:<\/p>\n<ul style=\"text-align: justify;\">\n<li>\u03b3<sub>Ba\/La<\/sub> = (1.75 \u2013 <em>x<\/em>)\/2; derived utilizing rule (2b), which scales the outer-layer Ba<sup>+2<\/sup> content [= (1.75 \u2013 <em>x<\/em>)] to that of YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>92<\/sub> (= 2) [1].<\/li>\n<li>\u03b3<sub>O<\/sub> = [(<em>y<\/em> \u2013 <em>y<\/em><sub>0<\/sub>)\/(6.92 \u2013 6.35)]; deduced by taking <em>y<\/em> = 7.15 \u00b1 0.02 and <em>y<\/em><sub>0<\/sub> = 6.88 (at <em>x<\/em> = 0.40, near optimal stoichiometry) [1], and scaling to the corresponding oxygen content of YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub> participating in superconductivity [2].<\/li>\n<li>\u03b3<sub>La\/Ca<\/sub> = [1 + (2\u20133)\/3]<em>x<\/em> = 2<em>x<\/em>\/3; follows from rule (2a) for Ca<sup>+2<\/sup> substituting for La<sup>+3<\/sup> in the type II reservoir. Since both Ca and La have very low and nearly identical electronegativities (1.0 and 1.1, respectively), no additional factors come into play.<\/li>\n<\/ul>\n<p style=\"text-align: justify;\">By inserting the value for y \u2013 y<sub>0<\/sub> (= 0.27) into the above equation, and solving for <em>x<\/em>, one obtains a value of 0.46 which is in excellent agreement with average value of <em>x<\/em> = 0.45, thus verifying Eq. (2.3) of Ref. [2].<\/p>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman and A. T. Fiory, <a href=\"https:\/\/doi.org\/10.1103\/PhysRevB.86.144533\">Phys. Rev. B <b>86<\/b>, 144533 (2012)<\/a>.<\/li>\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow,\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#Y124\" name=\"Y124\"><\/a><\/p>\n<hr \/>\n<p><strong>YBa<sub>2<\/sub>Cu<sub>4<\/sub>O<sub>8<\/sub>\u00a0(12 G<\/strong><strong>Pa)<\/strong> (<em>Ammm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 104 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/YBa2Cu4O8.gif\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2265 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/YBa2Cu4O8.gif\" alt=\"YBa2Cu4O8\" width=\"176\" height=\"290\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">For this material, the valences and stoichiomentries are unchanged with respect to YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>, such that\u00a0\u03b3 = 1. \u00a0Therefore, the optimal transition temperature for this and all other REBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>7\u2013\u03b4<\/sub>\u00a0compounds is completely determined by the structural parameters, <em>A<\/em> and \u03b6 [1]:<\/p>\n<ul>\n<li>Type I reservoir: BaO-CuO-CuO-BaO<\/li>\n<li>Type II reservoir: CuO<sub>2<\/sub>-Y-CuO<sub>2<\/sub><\/li>\n<li>\u03c3 =\u00a0\u03c3<sub>0<\/sub><\/li>\n<li>\u03b7 = 2;\u00a0\u03bd=2<\/li>\n<li><em>A<\/em> = 14.2060 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 2.1658 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 103.19 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#Tl2201\" name=\"Tl2201\"><\/a><\/p>\n<hr \/>\n<p><strong>Tl<sub>2<\/sub>Ba<sub>2<\/sub>CuO<sub>6<\/sub><\/strong> (<em>I4\/mmm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 80 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Tl2Ba2CuO6.gif\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2271 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Tl2Ba2CuO6.gif\" alt=\"Tl2Ba2CuO6\" width=\"176\" height=\"290\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">Given the +3 charge state of Tl in Tl<sub>2<\/sub>Ba<sub>2<\/sub>CuO<sub>6<\/sub>, compared to Cu<sup>+2<\/sup> in the CuO chain layer of YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>, rule (2a) introduces a factor of 1\/2 in \u03b3. \u00a0The presence of the double TlO layer structure, in place of the single CuO chain layer in YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>, invokes an additional factor of 2 from rule (2b). \u00a0Combining the two factors then yields\u00a0[1,2]:<\/p>\n<ul>\n<li>Type I reservoir: BaO-TlO-TlO-BaO<\/li>\n<li>Type II reservoir: CuO<sub>2<\/sub><\/li>\n<li>\u03c3 = (1\/2)(2) \u03c3<sub>0<\/sub> = \u03c3<sub>0<\/sub> <sup>[2]<\/sup><\/li>\n<li>\u03b7 = 1;\u00a0\u03bd=2<\/li>\n<li><em>A<\/em> = 14.9460 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.9291 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 79.86 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<li>D. R. Harshman and A. T. Fiory,\u00a0<a href=\"https:\/\/doi.org\/10.1016\/j.jpcs.2015.04.019\">J. Phys. Chem. Solids\u00a0<strong>85<\/strong>, 106 (2015)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#Y124\" name=\"Tl2212\"><\/a><\/p>\n<hr \/>\n<p><strong>Tl<sub>2<\/sub>Ba<sub>2<\/sub>CaCu<sub>2<\/sub>O<sub>8<\/sub><\/strong>\u00a0(<em>I4\/mmm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 110 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Tl2Ba2CaCu2O8.gif\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2411 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Tl2Ba2CaCu2O8.gif\" alt=\"Tl2Ba2CaCu2O8\" width=\"176\" height=\"290\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">Given the +3 charge state of Tl in\u00a0Tl<sub>2<\/sub>Ba<sub>2<\/sub>CaCu<sub>2<\/sub>O<sub>8<\/sub>, compared to Cu<sup>+2<\/sup> in the CuO chain layer of YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>, rule (2a) introduces a factor of 1\/2 in \u03b3. \u00a0The presence of the double TlO layer structure, in place of the single CuO chain layer in YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>, invokes an additional factor of 2 from rule (2b). \u00a0Combining the two factors then yields\u00a0[1,2]:<\/p>\n<ul>\n<li>Type I reservoir: BaO-TlO-TlO-BaO<\/li>\n<li>Type II reservoir: CuO<sub>2<\/sub>-Ca-CuO<sub>2<\/sub><\/li>\n<li>\u03c3 = (1\/2)(2) \u03c3<sub>0<\/sub> = \u03c3<sub>0<\/sub> <sup>[2]<\/sup><\/li>\n<li>\u03b7 = 2;\u00a0\u03bd=2<\/li>\n<li><em>A<\/em> = 14.8610 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 2.0139 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 108.50 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<li>D. R. Harshman and A. T. Fiory,\u00a0<a href=\"https:\/\/doi.org\/10.1016\/j.jpcs.2015.04.019\">J. Phys. Chem. Solids\u00a0<strong>85<\/strong>, 106 (2015)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#Y124\" name=\"Tl2223\"><\/a><\/p>\n<hr \/>\n<p><strong>Tl<sub>2<\/sub>Ba<sub>2<\/sub>Ca<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>10<\/sub><\/strong> (<em>I4\/mmm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 130 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Tl2Ba2Ca2Cu3O10.gif\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2416 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Tl2Ba2Ca2Cu3O10.gif\" alt=\"Tl2Ba2Ca2Cu3O10\" width=\"176\" height=\"290\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">Given the +3 charge state of Tl in\u00a0Tl<sub>2<\/sub>Ba<sub>2<\/sub>Ca<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>10<\/sub>, compared to Cu<sup>+2<\/sup> in the CuO chain layer of YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>, rule (2a) introduces a factor of 1\/2 in \u03b3. \u00a0The presence of the double TlO layer structure, in place of the single CuO chain layer in YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>, invokes an additional factor of 2 from rule (2b). \u00a0Combining the two factors then yields\u00a0[1,2]:<\/p>\n<ul>\n<li>Type I reservoir:\u00a0BaO-TlO-TlO-BaO<\/li>\n<li>Type II reservoir:\u00a0 CuO<sub>2<\/sub>-Ca-CuO<sub>2<\/sub>-Ca-CuO<sub>2<\/sub><\/li>\n<li>\u03c3 = (1\/2)(2) \u03c3<sub>0<\/sub> = \u03c3<sub>0<\/sub> <sup>[2]<\/sup><\/li>\n<li>\u03b7 = 3;\u00a0\u03bd=2<\/li>\n<li><em>A<\/em> = 14.8248 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 2.0559 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 130.33 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<li>D. R. Harshman and A. T. Fiory,\u00a0<a href=\"https:\/\/doi.org\/10.1016\/j.jpcs.2015.04.019\">J. Phys. Chem. Solids\u00a0<strong>85<\/strong>, 106 (2015)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#Tl1201_a\" name=\"Tl1201_a\"><\/a><\/p>\n<hr \/>\n<p><strong>TlBa<sub>1.2<\/sub>La<sub>0.8<\/sub>CuO<sub>5<\/sub><\/strong> (<a href=\"http:\/\/download.springer.com\/static\/pdf\/243\/chp%253A10.1007%252F978-3-642-22847-6_660.pdf?originUrl=http%3A%2F%2Flink.springer.com%2Fchapter%2F10.1007%2F978-3-642-22847-6_660&amp;token2=exp=1458857826~acl=%2Fstatic%2Fpdf%2F243%2Fchp%25253A10.1007%25252F978-3-642-22847-6_660.pdf%3ForiginUrl%3Dhttp%253A%252F%252Flink.springer.com%252Fchapter%252F10.1007%252F978-3-642-22847-6_660*~hmac=4bbccaafacfc072238d677da492c9627e78c40f4f939082b032d3b2dbc230fce\">P4\/mmm<\/a>, T<sub>C0<\/sub><sup>meas<\/sup> = 45.4 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Mochiku_JJAP_28_pL1926_1989-TlSrLaCuO6-image.jpg\" rel=\"attachment wp-att-3439\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-full wp-image-3439\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Mochiku_JJAP_28_pL1926_1989-TlSrLaCuO6-image.jpg\" alt=\"Mochiku_JJAP_28_pL1926_1989-TlSrLaCuO6-image\" width=\"176\" height=\"192\" srcset=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Mochiku_JJAP_28_pL1926_1989-TlSrLaCuO6-image.jpg 176w, http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Mochiku_JJAP_28_pL1926_1989-TlSrLaCuO6-image-138x150.jpg 138w\" sizes=\"auto, (max-width: 176px) 100vw, 176px\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">Given the +3 charge state of Tl in TlBa<sub>1.2<\/sub>La<sub>0.8<\/sub>CuO<sub>5<\/sub>, compared to Cu<sup>+2<\/sup> in the CuO chain layer of YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>, rule (2a) introduces a factor of 1\/2 in \u03b3. \u00a0The presence of only 1.2 Ba ions in the outer layers, compare to two in YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>, invokes an additional \u03b3-factor of 1.2\/2 = 0.6 from rule (2b). \u00a0Combining the two factors then yields\u00a0[1,2]:<\/p>\n<ul>\n<li>Type I reservoir: (Ba<sub>1.2<\/sub>La<sub>0.8<\/sub>)O-TlO-(Ba<sub>1.2<\/sub>La<sub>0.8<\/sub>)O<\/li>\n<li>Type II reservoir:\u00a0CuO<sub>2<\/sub><\/li>\n<li>\u03c3 = (1\/2)(0.6) \u03c3<sub>0<\/sub> = 0.300 \u03c3<sub>0<\/sub> <sup>[2]<\/sup><\/li>\n<li>\u03b7 = 1;\u00a0\u03bd=2<\/li>\n<li><em>A<\/em> = 14.7475 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.9038 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 44.62 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<li>D. R. Harshman and A. T. Fiory,\u00a0<a href=\"https:\/\/doi.org\/10.1016\/j.jpcs.2015.04.019\">J. Phys. Chem. Solids\u00a0<strong>85<\/strong>, 106 (2015)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#Tl1201_b\" name=\"Tl1201_b\"><\/a><\/p>\n<hr \/>\n<p><strong>Tl<sub>0.7<\/sub>LaSrCuO<sub>5<\/sub><\/strong> (P4\/mmm, T<sub>C0<\/sub><sup>meas<\/sup> = 37 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Mochiku_JJAP_28_pL1926_1989-TlSrLaCuO6-image.jpg\" rel=\"attachment wp-att-3439\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-full wp-image-3439\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Mochiku_JJAP_28_pL1926_1989-TlSrLaCuO6-image.jpg\" alt=\"Mochiku_JJAP_28_pL1926_1989-TlSrLaCuO6-image\" width=\"176\" height=\"192\" srcset=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Mochiku_JJAP_28_pL1926_1989-TlSrLaCuO6-image.jpg 176w, http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Mochiku_JJAP_28_pL1926_1989-TlSrLaCuO6-image-138x150.jpg 138w\" sizes=\"auto, (max-width: 176px) 100vw, 176px\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">Given the +3 charge state of Tl in\u00a0Tl<sub>0.7<\/sub>LaSrCuO<sub>5<\/sub>, compared to Cu<sup>+2<\/sup> in the CuO chain layer of YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>, and treating vacancies as non-contributors (i.e., equivalent to a factor of 1\/4 &#8211; see Bi-2212), rule (2a) introduces a \u03b3-factor of [0.7(1\/2) + 0.3(1\/4)]. \u00a0The presence of only 1 Sr<sup>+2<\/sup> ion in the outer layers, compare to two Ba<sup>+2<\/sup> ions in YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>, invokes an additional \u03b3-factor of 1\/2 from rule (2b). \u00a0Combining the two factors then yields\u00a0[1,2]:<\/p>\n<ul>\n<li>Type I reservoir: LaSrO-Tl<sub>0.7<\/sub>O-LaSrO<\/li>\n<li>Type II reservoir:\u00a0CuO<sub>2<\/sub><\/li>\n<li>\u03c3 = (1\/2)[0.7(1\/2) + 0.3(1\/4)] \u03c3<sub>0<\/sub> = 0.2125 \u03c3<sub>0 <\/sub>\u00a0<sup>[2]<\/sup><\/li>\n<li>\u03b7 = 1;\u00a0\u03bd=2<\/li>\n<li><em>A<\/em> = 14.2453 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.8368 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 39.63 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<li>D. R. Harshman and A. T. Fiory,\u00a0<a href=\"https:\/\/doi.org\/10.1016\/j.jpcs.2015.04.019\">J. Phys. Chem. Solids\u00a0<strong>85<\/strong>, 106 (2015)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#Tl1212\" name=\"Tl1212\"><\/a><\/p>\n<hr \/>\n<p><strong>TlBa<sub>2<\/sub>CaCu<sub>2<\/sub>O<sub>7\u2013\u03b4<\/sub><\/strong> (<em>P4\/mmm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 103 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/TlBa2CaCu2O7-d.gif\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2436 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/TlBa2CaCu2O7-d.gif\" alt=\"TlBa2CaCu2O7-d\" width=\"176\" height=\"290\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">In the case of the two Tl-based compounds containing a single\u00a0TlO layer, TlBa<sub>2<\/sub>CaCu<sub>2<\/sub>O<sub>7\u2013\u03b4<\/sub>\u00a0(Tl-1212) and\u00a0TlBa<sub>2<\/sub>Ca<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>9\u2013\u03b4<\/sub>\u00a0(Tl-1223), the mixed-valence nature of Tl places the average Tl oxidation\u00a0state between\u00a0<em>f<\/em><sub>+1<\/sub>\u00a0and\u00a0<em>f<\/em><sub>+3<\/sub>. \u00a0As a consequence, \u03c3 becomes a\u00a0function of the fractional distribution of the monovalent and trivalent Tl oxidation states, which is measured experimentally. Denoting <em>f<\/em><sub>+1<\/sub> to be the fraction of monovalent cations in the inner\u00a0TlO layer (i.e., Tl<sup>+1<\/sup>), and apportioning a mixture of +1 and +3\u00a0valencies in rule (2a), one has \u03b3\u00a0= (2)<em>f<\/em><sub>+1<\/sub> + \u00a0(1\/2)(1 \u2013 <em>f<\/em><sub>+1<\/sub>) for these\u00a0optimal compounds; therefore,\u00a0\u03c3 = \u03b3 \u03c3<sub>0<\/sub> = (1.5 <em>f<\/em><sub>+1<\/sub> + 0.5) \u03c3<sub>0<\/sub>. \u00a0Knowing <em>f<\/em><sub>+1<\/sub> thus determines \u03c3 or, alternatively, <em>f<\/em><sub>+1<\/sub> can be\u00a0deduced for a given value of \u03c3. Given the absence of +3 cations in\u00a0the outer type I layers, one may assume for argument&#8217;s sake that,\u00a0as with their double-TlO layer counterparts, charge\u00a0depletion below \u03c3<sub>0<\/sub> does not occur for these compounds; taking\u00a0optimal \u03c3 = \u03c3<sub>0<\/sub> one has [1,2]:<\/p>\n<ul>\n<li>Type I reservoir:\u00a0BaO-TlO-BaO<\/li>\n<li>Type II reservoir: CuO<sub>2<\/sub>-Ca-CuO<sub>2<\/sub><\/li>\n<li>\u03c3 = (1.5 <em>f<\/em><sub>+1<\/sub> + 0.5) \u03c3<sub>0<\/sub> = \u03c3<sub>0<\/sub> (assumed the same as Tl-1223) <sup>[2]<\/sup><\/li>\n<li><em>f<\/em><sub>+1<\/sub> = 1\/3;\u00a0<em>f<\/em><sub>+3<\/sub> = 2\/3\u00a0<sup>[2]<\/sup><\/li>\n<li>\u03b7 = 2;\u00a0\u03bd=2<\/li>\n<li><em>A<\/em> = 14.8734 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 2.0815 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 104.93 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<li>D. R. Harshman and A. T. Fiory,\u00a0<a href=\"https:\/\/doi.org\/10.1016\/j.jpcs.2015.04.019\">J. Phys. Chem. Solids\u00a0<strong>85<\/strong>, 106 (2015)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#Tl1223\" name=\"Tl1223\"><\/a><\/p>\n<hr \/>\n<p><strong>TlBa<sub>2<\/sub>Ca<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>9\u2013\u03b4<\/sub><\/strong> (<em>P4\/mmm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 133.5 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/TlBa2Ca2Cu3O9-d.gif\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2440 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/TlBa2Ca2Cu3O9-d.gif\" alt=\"TlBa2Ca2Cu3O9-d\" width=\"176\" height=\"290\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">In the case of the two Tl-based compounds containing a single\u00a0TlO layer, TlBa<sub>2<\/sub>CaCu<sub>2<\/sub>O<sub>7\u2013\u03b4<\/sub>\u00a0(Tl-1212) and\u00a0TlBa<sub>2<\/sub>Ca<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>9\u2013\u03b4<\/sub>\u00a0(Tl-1223), the mixed-valence nature of Tl places the average Tl oxidation\u00a0state between\u00a0<em>f<\/em><sub>+1<\/sub>\u00a0and\u00a0<em>f<\/em><sub>+3<\/sub>. \u00a0As a consequence, \u03c3 becomes a\u00a0function of the fractional distribution of the monovalent and trivalent Tl oxidation states, which is measured experimentally. Denoting <em>f<\/em><sub>+1<\/sub> to be the fraction of monovalent cations in the inner\u00a0TlO layer (i.e., Tl<sup>+1<\/sup>), and apportioning a mixture of +1 and +3\u00a0valencies in rule (2a), one has \u03b3\u00a0= (2)<em>f<\/em><sub>+1<\/sub> + \u00a0(1\/2)(1 \u2013 <em>f<\/em><sub>+1<\/sub>) for these\u00a0optimal compounds; therefore,\u00a0\u03c3 = \u03b3 \u03c3<sub>0<\/sub> = (1.5 <em>f<\/em><sub>+1<\/sub> + 0.5) \u03c3<sub>0<\/sub>. \u00a0Knowing <em>f<\/em><sub>+1<\/sub> thus determines \u03c3 or, alternatively, <em>f<\/em><sub>+1<\/sub> can be\u00a0deduced for a given value of \u03c3. Given the absence of +3 cations in\u00a0the outer type I layers, one may assume for argument&#8217;s sake that,\u00a0as with their double-TlO layer counterparts, charge\u00a0depletion below \u03c3<sub>0<\/sub> does not occur for these compounds; taking\u00a0optimal \u03c3 = \u03c3<sub>0<\/sub> one has [1,2]:<\/p>\n<ul>\n<li>Type I reservoir:\u00a0BaO-TlO-BaO<\/li>\n<li>Type II reservoir:\u00a0CuO<sub>2<\/sub>-Ca-CuO<sub>2<\/sub>-Ca-CuO<sub>2<\/sub><\/li>\n<li>\u03c3 = (1.5 <em>f<\/em><sub>+1<\/sub> + 0.5) \u03c3<sub>0<\/sub> = \u03c3<sub>0<\/sub> (assumed) <sup>[2]<\/sup><\/li>\n<li><em>f<\/em><sub>+1<\/sub> = 1\/3; <em>f<\/em><sub>+3<\/sub> = 2\/3\u00a0<sup>[2]<\/sup> (shown experimentally) <sup>[2]<\/sup><\/li>\n<li>\u03b7 = 3;\u00a0\u03bd=2<\/li>\n<li><em>A<\/em> = 14.7686 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 2.0315 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 132.14 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<li>D. R. Harshman and A. T. Fiory,\u00a0<a href=\"https:\/\/doi.org\/10.1016\/j.jpcs.2015.04.019\">J. Phys. Chem. Solids\u00a0<strong>85<\/strong>, 106 (2015)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#Hg1223\" name=\"Hg1223\"><\/a><\/p>\n<hr \/>\n<p><strong>HgBa<sub>2<\/sub>Ca<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>8+\u03b4<\/sub><\/strong> (<em>P4\/mmm<\/em>, \u03b4 = 0.27\u00b10.04, T<sub>C0<\/sub><sup>meas<\/sup> = 134.43 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Hg1223-e1458843837300.jpg\" rel=\"attachment wp-att-3396\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-full wp-image-3396\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Hg1223-e1458843837300.jpg\" alt=\"Hg1223\" width=\"176\" height=\"401\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">For this material, it is assumed that \u03c3 = \u03c3<sub>0<\/sub>. \u00a0Thus one has [1]:<\/p>\n<ul>\n<li>Type I reservoir: BaO-HgO<sub>x<\/sub>-BaO<\/li>\n<li>Type II reservoir:\u00a0CuO<sub>2<\/sub>-Ca-CuO<sub>2<\/sub>-Ca-CuO<sub>2<\/sub><\/li>\n<li>\u03c3 =\u00a0\u03c3<sub>0<\/sub> (assumed)<\/li>\n<li>\u03b7 = 3;\u00a0\u03bd=2<\/li>\n<li><em>A<\/em> = 14.8060 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.9959 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 134.33 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b> 349501 (2011)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#Hg1223_25Gpa\" name=\"Hg1223_25GPa\"><\/a><\/p>\n<hr \/>\n<p><strong>HgBa<sub>2<\/sub>Ca<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>8+\u03b4<\/sub><\/strong>\u00a0<strong>(25 GPa)<\/strong> (<em>P4\/mmm<\/em>, \u03b4 = 0.27\u00b10.04, T<sub>C0<\/sub><sup>meas<\/sup> = 145 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Hg1223-e1458843837300.jpg\" rel=\"attachment wp-att-3396\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-full wp-image-3396\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Hg1223-e1458843837300.jpg\" alt=\"Hg1223\" width=\"176\" height=\"401\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">For this material, it is assumed that \u03c3 = \u03c3<sub>0<\/sub>, where the increase in T<sub>C0<\/sub><sup>calc<\/sup>\u00a0over the 0 GPa value is directly related to the decrease in <em>A<\/em> and \u03b6 . Thus one has [1]:<\/p>\n<ul>\n<li>Type I reservoir:\u00a0BaO-HgO<sub>x<\/sub>-BaO<\/li>\n<li>Type II reservoir:\u00a0CuO<sub>2<\/sub>-Ca-CuO<sub>2<\/sub>-Ca-CuO<sub>2<\/sub><\/li>\n<li>\u03c3 =\u00a0\u03c3<sub>0<\/sub> (assumed)<\/li>\n<li>\u03b7 = 3;\u00a0\u03bd=2<\/li>\n<li><em>A<\/em> = 13.6449 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.9326 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 144.51 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b> 349501 (2011)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#Hg1201\" name=\"Hg1201\"><\/a><\/p>\n<hr \/>\n<p><strong>HgBa<sub>2<\/sub>CuO<sub>4.15<\/sub><\/strong>\u00a0(<em>P4\/mmm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 95 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/HgBa2CuO4-d.gif\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2457 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/HgBa2CuO4-d.gif\" alt=\"HgBa2CuO4+d\" width=\"176\" height=\"290\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">We know of at least two optimal compounds for which \u03c3 &gt; \u03c3<sub>0<\/sub>, HgBa<sub>2<\/sub>CuO<sub>4.15<\/sub>\u00a0and HgBa<sub>2<\/sub>CaCu<sub>2<\/sub>O<sub>6.22<\/sub>, T<sub>C0<\/sub> = 95 K and 127 K, respectively, where the two electrons per excess oxygen (0.15 and 0.22, respectively) are equally distributed among the (3+\u03b7) layers (this is equivalent to dividing the carriers between the two reservoirs, and then by the average number of layers per reservoir). \u00a0For HgBa<sub>2<\/sub>CuO<sub>4.15<\/sub>, one then finds that \u03c3 = \u03c3<sub>0<\/sub> + 2(0.15)\/(3+1) = 0.3030. \u00a0This enhancement in T<sub>C0<\/sub><sup>meas<\/sup>\u00a0is attributed to the unique structure of the Hg compounds which provides vacancy locations for excess oxygen and the \u2264 2 valence of Hg.\u00a0Thus one has [1]:<\/p>\n<ul>\n<li>Type I reservoir:\u00a0BaO-HgO-BaO<\/li>\n<li>Type II reservoir:\u00a0CuO<sub>2<\/sub><\/li>\n<li>\u03c3 =\u00a0\u03c3 = \u03c3<sub>0<\/sub> + 2(0.15)\/(3+1) = \u03c3<sub>0<\/sub>\u00a0+ 0.075 = 0.3030<\/li>\n<li>\u03b7 = 1;\u00a0\u03bd=2<\/li>\n<li><em>A<\/em> = 15.0362 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.9214 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 92.16 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#Hg1212\" name=\"Hg1212\"><\/a><\/p>\n<hr \/>\n<p><strong>HgBa<sub>2<\/sub>CaCu<sub>2<\/sub>O<sub>6.22<\/sub><\/strong>\u00a0(<em>P4\/mmm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 127 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Hg1212-e1459047558266.jpg\" rel=\"attachment wp-att-3443\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-full wp-image-3443\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Hg1212-e1459047558266.jpg\" alt=\"Hg1212\" width=\"176\" height=\"455\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">We know of at least two optimal compounds for which \u03c3 &gt; \u03c3<sub>0<\/sub>, HgBa<sub>2<\/sub>CuO<sub>4.15<\/sub>\u00a0and HgBa<sub>2<\/sub>CaCu<sub>2<\/sub>O<sub>6.22<\/sub>, T<sub>C0<\/sub> = 95 K and 127 K, where the two electrons per excess oxygen (0.15 and 0.22, respectively) are equally distributed among the (3+\u03b7) layers (this is equivalent to dividing the carriers between the two reservoirs, and then by the average number of layers per reservoir). \u00a0For HgBa<sub>2<\/sub>CaCu<sub>2<\/sub>O<sub>6.22<\/sub>, one then finds that \u03c3 = \u03c3<sub>0<\/sub> + 2(0.22)\/(3+1) = 0.3160. \u00a0This enhancement in T<sub>C0<\/sub><sup>meas<\/sup>\u00a0is attributed to the unique structure of the Hg compounds which provides vacancy locations for excess oxygen and the \u2264 2 valence of Hg.\u00a0Thus one has [1]:<\/p>\n<ul>\n<li>Type I reservoir:\u00a0BaO-HgO-BaO<\/li>\n<li>Type II reservoir:\u00a0CuO<sub>2<\/sub>-Ca-CuO<sub>2<\/sub><\/li>\n<li>\u03c3 =\u00a0and \u03c3 = \u03c3<sub>0<\/sub> + 2(0.22)\/(3+2) = \u03c3<sub>0<\/sub>\u00a0+ 0.088 = 0.3160,<\/li>\n<li>\u03b7 = 2;\u00a0\u03bd=2<\/li>\n<li><em>A<\/em> = 14.9375 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 2.0390 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 125.84 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#La214\" name=\"La214\"><\/a><\/p>\n<hr \/>\n<p><strong>La<sub>1.837<\/sub>Sr<sub>0.163<\/sub>CuO<sub>4\u2013\u03b4<\/sub><\/strong> (<em>I4\/mmm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 38 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/LaBa2CuO4-d.gif\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2469 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/LaBa2CuO4-d.gif\" alt=\"(LaBa)2CuO4-d\" width=\"176\" height=\"290\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">Since x<sub>0<\/sub> = 0, the total charge doping is 0.163. \u00a0This charge is accordingly distribution between the type I and type II reservoirs [rule (1b)], thereby introducing a factor of 1\/2 in \u03b3 [rule (1b)]. \u00a0As there are two SrO layers in the type I reservoir (i.e., \u03bd = 2) rule (1a) provides an additional factor of 1\/2 such that [1]:<\/p>\n<ul>\n<li>Type I reservoir: (La<sub>1.837<\/sub>Sr<sub>0.163<\/sub>)O-(La<sub>1.837<\/sub>Sr<sub>0.163<\/sub>)O<\/li>\n<li>Type II reservoir:\u00a0CuO<sub>2<\/sub><\/li>\n<li>\u03c3 = (0.163)(1\/2)(1\/2) = 0.048<\/li>\n<li>\u03b7 = 1;\u00a0\u03bd = 2<\/li>\n<li><em>A<\/em> = 14.2268 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.7828 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 37.47 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b> 349501 (2011)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#La2126\" name=\"La2126\"><\/a><\/p>\n<hr \/>\n<p><strong>La<sub>1.8<\/sub>Sr<sub>0.2<\/sub>CaCu<sub>2<\/sub>O<sub>6\u00b1\u03b4<\/sub><\/strong> (<em>I4\/mmm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 58 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/La1.8Sr0.2CaCu2O6-d.gif\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2470 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/La1.8Sr0.2CaCu2O6-d.gif\" alt=\"La1.8Sr0.2CaCu2O6+d\" width=\"176\" height=\"290\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">Since x<sub>0<\/sub> = 0, the total charge doping is 0.2. \u00a0This charge is accordingly distribution between the type I and type II reservoirs, thereby introducing a factor of 1\/2 in \u03b3 [rule (1b)]. \u00a0As there are two SrO layers in the type I reservoir (i.e., \u03bd = 2) rule (1a) provides an additional factor of 1\/2 such that [1]:<\/p>\n<ul>\n<li>Type I reservoir: (La<sub>1.8<\/sub>Sr<sub>0.2<\/sub>)O-(La<sub>1.8<\/sub>Sr<sub>0.2<\/sub>)O<\/li>\n<li>Type II reservoir:\u00a0CuO<sub>2<\/sub>-Ca-CuO<sub>2<\/sub><\/li>\n<li>\u03c3 = (0.2)(1\/2)(1\/2) = 0.05<\/li>\n<li>\u03b7 = 2 ;\u00a0\u03bd = 2<\/li>\n<li><em>A<\/em> = 14.3761 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.7829 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 58.35 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#SrLa112\" name=\"SrLa112\"><\/a><\/p>\n<hr \/>\n<p><strong>(Sr<sub>0.9<\/sub>La<sub>0.1<\/sub>)CuO<sub>2<\/sub><\/strong> (<em>P4\/mmm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 43 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Sr0.9La0.1CuO2.gif\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2471 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Sr0.9La0.1CuO2.gif\" alt=\"(Sr0.9La0.1)CuO2\" width=\"176\" height=\"290\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">For this material, superconductivity occurs with La doping (with x<sub>0<\/sub> = 0). \u00a0Given that the total charge doping is 0.1, which is distributed equally between the type I and type II reservoir, rule (1b) introduces a factor of 1\/2 in \u03b3. \u00a0Since \u03bd = 1, there are no additional \u03b3-factors such that [1]:<\/p>\n<ul>\n<li>Type I reservoir:\u00a0(Sr<sub>0.9<\/sub>La<sub>0.1<\/sub>)<\/li>\n<li>Type II reservoir:\u00a0CuO<sub>2<\/sub><\/li>\n<li>\u03c3 = (0.1)(1\/2) = 0.05<\/li>\n<li>\u03b7 = 1;\u00a0\u03bd = 1<\/li>\n<li><em>A<\/em> = 15.6058 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.7051 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 41.41 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b> 349501 (2011)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#ruth\" name=\"ruth\"><\/a><\/p>\n<hr \/>\n<p><strong>Ba<sub>2<\/sub>Y(Ru<sub>0.9<\/sub>Cu<sub>0.1<\/sub>)O<sub>6<\/sub><\/strong> (<em>Fm3m<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 35 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Parkinson_JMC_13_p1468_2003-Ba_image-e1459017792391.jpg\" rel=\"attachment wp-att-3437\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-full wp-image-3437\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Parkinson_JMC_13_p1468_2003-Ba_image-e1459017792391.jpg\" alt=\"Parkinson_JMC_13_p1468_2003-Ba_image\" width=\"176\" height=\"191\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">The ruthenate compounds\u00a0A<sub>2<\/sub>Y(Ru<sub>0.9<\/sub>Cu<sub>0.1<\/sub>)O<sub>6<\/sub>\u00a0(with A = Ba\u00a0or Sr; x = 0.05\u20130.15) are double-perovskites containing no\u00a0cuprate planes and with \u03b7 = \u03bd = 1 (reference [82] in original paper [1]). \u00a0The determination of \u03b3 is done using charge allocation, wherein rule (1b) introduces the factor 1\/2. \u00a0In the lower\u00a0limit, one expects a minimum of \u223c 2 charges per Cu dopant, which are shared between two charge reservoirs of each layer\u00a0type [AO and 1\/2 (YRu<sub>1\u2013x<\/sub>Cu<sub>x<\/sub>O<sub>4<\/sub>)], producing a net factor of\u00a0unity. \u00a0Thus, for Ba<sub>2<\/sub>YRu<sub>0.9<\/sub>Cu<sub>0.1<\/sub>O<sub>6<\/sub> (with T<sub>C0<\/sub><sup>meas<\/sup> \u223c 30\u201340 K), we have \u03b3 = (1\/2)(1) = 1\/2, as stated by\u00a0equation in the original paper of [1]. \u00a0The corrigendum also corrects\u00a0a typographical correction in the definition of the corresponding ruthenate type II reservoir in the last column of table 1 in the original paper [1], which should read 1\/2 (YRu<sub>0.9<\/sub>Cu<sub>0.1<\/sub>O<sub>4<\/sub>). \u00a0Thus one has [1]:<\/p>\n<ul>\n<li>Type I reservoir: BaO<\/li>\n<li>Type II reservoir:\u00a0\u00bd(YRu<sub>0.9<\/sub>Cu<sub>0.1<\/sub>O<sub>4<\/sub>)<\/li>\n<li>\u03c3 = (0.1)(1\/2) = 0.05<\/li>\n<li>\u03b7 = 1;\u00a0\u03bd = 1<\/li>\n<li><em>A<\/em> = 17.3208 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 2.0809 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 32.21 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#PbCu1212\" name=\"PbCu1212\"><\/a><\/p>\n<hr \/>\n<p><strong>(Pb<sub>0.5<\/sub>Cu<sub>0.5<\/sub>)Sr<sub>2<\/sub>(Y\/Ca)Cu<sub>2<\/sub>O<sub>7\u2013\u03b4<\/sub><\/strong> (<span style=\"color: #ff0000;\">P4\/mmm<\/span>; T<sub>C0<\/sub><sup>meas<\/sup> = 67 K)<img loading=\"lazy\" decoding=\"async\" class=\"alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/TlBa2CaCu2O7-d.gif\" alt=\"\" width=\"176\" height=\"290\" \/><\/p>\n<p style=\"text-align: justify;\">As the description reported in the original work [1] was a bit misleading, so a correct discussion is given here [2]. \u00a0<span style=\"color: #ff0000;\">The (Pb<sub>0.5<\/sub>Cu<sub>0.5.<\/sub>)Sr<sub>2<\/sub>\u00a0structure makes up the type I reservoir in this material, with both Pb and Cu possessing a +3 charge state (primarily, e.g., from Pb-O bond length measurements). Using Stoichiometric (valency) scaling with respect to YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>, rule (2a) introduces a factor of 1\/2 for both. \u00a0However, the large electronegativity (see discussion of Bi-2212 in Ref. [2]) for Pb (\u03c7 = 2.33) when compared with Cu (\u03c7 = 1.90), an additional factor of 1\/2 must accompany the Pb component, such that, \u03b3 = (1\/2)(0.5<sub>Pb<\/sub>\/2 + 0.5<sub>Cu<\/sub>) = (1\/2)(3\/4). \u00a0Thus one has [1-3]:<\/span><\/p>\n<ul>\n<li>Type I reservoir: SrO-(Pb<sub>0.5<\/sub>Cu<sub>0.5<\/sub>)O-SrO<\/li>\n<li>Type II reservoir:\u00a0CuO<sub>2<\/sub>-(Y\/Ca)-CuO<sub>2<\/sub><\/li>\n<li>\u03c3 = (1\/2)(3\/4) \u03c3<sub>0<\/sub>\u00a0= 0.375 \u03c3<sub>0<\/sub><\/li>\n<li>\u03b7 = 2;\u00a0\u03bd=2<\/li>\n<li><em>A<\/em> = 14.5771 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.9967 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 67.76 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<li>D. R. Harshman and A. T. Fiory,\u00a0<a href=\"https:\/\/doi.org\/10.1016\/j.jpcs.2015.04.019\">J. Phys. Chem. Solids\u00a0<strong>85<\/strong>, 106 (2015)<\/a>.<\/li>\n<li><span style=\"color: #ff0000;\">Unpublished (2014)<\/span>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#Bi2212\" name=\"Bi2212\"><\/a><\/p>\n<hr \/>\n<p><strong>Bi<sub>2<\/sub>Sr<sub>2<\/sub>CaCu<sub>2<\/sub>O<sub>8+\u03b4<\/sub><\/strong> (<em>N Bbmb\/1<span style=\"text-decoration: overline;\">1<\/span>1<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 89 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Tl2Ba2CaCu2O8.gif\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2411 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Tl2Ba2CaCu2O8.gif\" alt=\"Tl2Ba2CaCu2O8\" width=\"176\" height=\"290\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">In\u00a0Bi<sub>2<\/sub>Sr<sub>2<\/sub>(Ca,Y)<sub>x<\/sub>Cu<sub>2<\/sub>O<sub>8+\u03b4<\/sub>\u00a0(Bi-2212), where excess oxygen located in\u00a0the Bi<sub>2<\/sub>O<sub>2<\/sub> block, as well as cation stoichiometry and substitutional defects, are correlated with a strong incommensurate\u00a0modulation along the <em>b<\/em>-axis of the basal plane [1,2]. \u00a0This extra oxygen\u00a0content, which appears to be enhanced (along with T<sub>C<\/sub>) by increasing the Ca vacancies (for x &lt; 1, with zero Y content) or the Y\/Ca substitution ratio (x\u00a0\u2248 1), introduces additional carriers for which the cation scaling rules alone do not account (accurate knowledge of the excess oxygen content in the Bi<sub>2<\/sub>O<sub>2<\/sub> block would be required in order\u00a0to apply anion scaling). \u00a0Variation of \u03b6 for non-stoichiometric\u00a0compositions would also come into play. Consequently, cation\u00a0scaling to YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub> is applicable only\u00a0the near stoichiometric Bi<sub>2<\/sub>Sr<sub>2<\/sub>CaCu<sub>2<\/sub>O<sub>8+\u03b4<\/sub>, compound (as-grown\u00a0and unannealed), assuming minimal extra-oxygen enhancement\u00a0in carrier density, and having a measured transition of 89 K [2]. \u00a0Given that there are two BiO layers compared to the one CuO chain in YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>, rule (2b) introduces a \u03b3-factor of 2, and since Bi<sup>+3<\/sup> is mapped onto the chain Cu<sup>+2<\/sup> cation, rule (2a) provides another factor of 1\/2. \u00a0<span style=\"color: #ff0000;\">Finally, because the electronegativity [2] of Bi (\u03c7 = 2.02) is significantly greater than that of Cu (\u03c7 = 1.90), charge transfer along the hard axis is suppressed, generating another factor of 1\/2. \u00a0Utilizing more recent structural refinement data\u00a0specific to a near-stoichiometric single-crystal sample at 12 K (see Ref. [2])<\/span>, one then has [1,2]:<\/p>\n<ul>\n<li>Type I reservoir: SrO-BiO-BiO-SrO<\/li>\n<li>Type II reservoir:\u00a0CuO<sub>2<\/sub>-Ca-CuO<sub>2<\/sub><\/li>\n<li>\u03c3 = (2)(1\/2)(1\/2) \u03c3<sub>0<\/sub>\u00a0= 0.5 \u03c3<sub>0<\/sub><\/li>\n<li>\u03b7 = 2;\u00a0\u03bd=2<\/li>\n<li><em>A<\/em> = 14.5201 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.7500 \u00c5 <sup>[2]<\/sup><\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 89.32 K <sup>[2]<\/sup><\/li>\n<\/ul>\n<p>Note that the value of 86.65 K originally\u00a0published in Ref. [1] was obtained using structural data for a nonstoichiometric powder sample.<\/p>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<li>D. R. Harshman and A. T. Fiory,\u00a0<a href=\"https:\/\/doi.org\/10.1016\/j.jpcs.2015.04.019\">J. Phys. Chem. Solids\u00a0<strong>85<\/strong>, 106 (2015)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#BiPb2223\" name=\"BiPb2223\"><\/a><\/p>\n<hr \/>\n<p><strong>(Bi\/Pb)<sub>2<\/sub>Sr<sub>2<\/sub>Ca<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>10+\u03b4<\/sub><\/strong> (<em>Fmmm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 112 K)<strong><a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Tl2Ba2Ca2Cu3O10.gif\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2416 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Tl2Ba2Ca2Cu3O10.gif\" alt=\"Tl2Ba2Ca2Cu3O10\" width=\"176\" height=\"290\" \/><\/a><\/strong><\/p>\n<p style=\"text-align: justify;\">Given that there are two BiO layers compared to the one CuO chain in YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>, rule (2b) introduces a \u03b3-factor of 2, and since Bi<sup>+3<\/sup> is mapped onto the chain Cu<sup>+2<\/sup> cation, rule (2a) provides another factor of 1\/2. \u00a0Finally, because the <span style=\"color: #ff0000;\">electronegativity<\/span>\u00a0(see discussion of Bi-2212 in Ref. [2]) of Bi (\u03c7 = 2.02) is significantly greater than that of Cu (\u03c7 = 1.90), charge transfer along the hard axis is suppressed, generating another factor of 1\/2. \u00a0Thus, one has [1,2]:<\/p>\n<ul>\n<li>Type I reservoir: SrO-(Bi\/Pb)-(Bi\/Pb)-SrO<\/li>\n<li>Type II reservoir:\u00a0CuO<sub>2<\/sub>-Ca-CuO<sub>2<\/sub>-Ca-CuO<sub>2<\/sub><\/li>\n<li>\u03c3 = (2)(1\/2)(1\/2) \u03c3<sub>0<\/sub>\u00a0= 0.5 \u03c3<sub>0<\/sub><\/li>\n<li>\u03b7 = 3;\u00a0\u03bd=2<\/li>\n<li><em>A<\/em> = 14.6340 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.6872 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 113.02 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<li>D. R. Harshman and A. T. Fiory,\u00a0<a href=\"https:\/\/doi.org\/10.1016\/j.jpcs.2015.04.019\">J. Phys. Chem. Solids\u00a0<strong>85<\/strong>, 106 (2015)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#PSYCCO\" name=\"PSYCCO\"><\/a><\/p>\n<hr \/>\n<p><strong>Pb<sub>2<\/sub>Sr<sub>2<\/sub>(Y\/Ca)Cu<sub>3<\/sub>O<sub>8<\/sub><\/strong> (T<sub>C0<\/sub><sup>meas<\/sup> = 75 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Pb2Sr2YCaCu3O8.gif\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2502 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Pb2Sr2YCaCu3O8.gif\" alt=\"Pb2Sr2(Y,Ca)Cu3O8\" width=\"176\" height=\"290\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">Given that there are two PbO layers compared to the one CuO chain in YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>, rule (2b) introduces a \u03b3-factor of 2. \u00a0Assuming a +3 average charge state for Pb, and since Pb<sup>+3<\/sup>O is mapped onto the chain Cu<sup>+2<\/sup>O, rule 2(a) provides a factor of 1\/2. \u00a0Finally, because the relative <span style=\"color: #ff0000;\">electronegativity<\/span>\u00a0(see discussion of Bi-2212 in Ref. [2]) of Pb (\u03c7 = 2.33) is significantly greater than that of Cu (\u03c7 = 1.90), charge transfer along the hard axis is suppressed, generating another factor of 1\/2. \u00a0Thus, one has [1,2]:<\/p>\n<ul>\n<li>Type I reservoir: SrO-PbO-Cu-PbO-SrO<\/li>\n<li>Type II reservoir:\u00a0CuO<sub>2<\/sub>-(Y\/Ca)-CuO<sub>2<\/sub><\/li>\n<li>\u03c3 = (2)(1\/2)(1\/2) \u03c3<sub>0<\/sub>\u00a0= 0.5 \u03c3<sub>0<\/sub><\/li>\n<li>\u03b7 = 2;\u00a0\u03bd=2<\/li>\n<li><em>A<\/em> = 14.6458 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 2.0280 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 76.74 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<li>D. R. Harshman and A. T. Fiory,\u00a0<a href=\"https:\/\/doi.org\/10.1016\/j.jpcs.2015.04.019\">J. Phys. Chem. Solids\u00a0<strong>85<\/strong>, 106 (2015)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#Bi2201\" name=\"Bi2201\"><\/a><\/p>\n<hr \/>\n<p><strong>Bi<sub>2<\/sub>(Sr<sub>1.6<\/sub>La<sub>0.4<\/sub>)CuO<sub>6+\u03b4<\/sub><\/strong> (<em>Cmmm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 34 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Bi2201-e1459061514514.jpg\" rel=\"attachment wp-att-3446\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-full wp-image-3446\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Bi2201-e1459061514514.jpg\" alt=\"Bi2201\" width=\"176\" height=\"219\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">For the single-layer material,\u00a0Bi<sub>2<\/sub>(Sr<sub>1.6<\/sub>La<sub>0.4<\/sub>)CuO<sub>6+\u03b4<\/sub>, the 1\/2 \u03b3-factor (relative to YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>) in rule (2a) arising from the presence of a double BiO layer structure (in place of a single CuO chain layer), would naturally\u00a0apply. \u00a0However, since YBa<sub>2<\/sub>Cu<sub>3<\/sub>O<sub>6.92<\/sub>\u00a0has two corresponding\u00a0Ba<sup>+2<\/sup> ions, the partial Sr<sup>+2<\/sup> doping (x = 1.6) of the outer layers\u00a0introduces a relative doping factor of ( 1.6 \u2212 1.16 ) = 0.44 according to rule (2b), where x<sub>0<\/sub> = 1.16. \u00a0Finally, the comparatively large <span style=\"color: #ff0000;\">electronegativity<\/span>\u00a0(see discussion of Bi-2212 in Ref. [2]) of Bi (\u03c7 = 2.02) to that of Cu (\u03c7 = 1.90) yields [1,2]:<\/p>\n<ul>\n<li>Type I reservoir: \u00bd(Sr<sub>1.6<\/sub>La<sub>0.4<\/sub>)-BiO-BiO-\u00bd(Sr<sub>1.6<\/sub>La<sub>0.4<\/sub>)<\/li>\n<li>Type II reservoir:\u00a0CuO<sub>2<\/sub><\/li>\n<li>\u03c3 = (1\/2)(0.44)(1\/2) \u03c3<sub>0<\/sub>\u00a0= 0.11 \u03c3<sub>0<\/sub><\/li>\n<li>\u03b7 = 1;\u00a0\u03bd=2<\/li>\n<li><em>A<\/em> = 14.5422 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.4880 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 34.81 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<li>D. R. Harshman and A. T. Fiory,\u00a0<a href=\"https:\/\/doi.org\/10.1016\/j.jpcs.2015.04.019\">J. Phys. Chem. Solids\u00a0<strong>85<\/strong>, 106 (2015)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#RuGd\" name=\"RuGd\"><\/a><\/p>\n<hr \/>\n<p><strong>RuSr<sub>2<\/sub>GdCu<sub>2<\/sub>O<sub>8<\/sub><\/strong> (<em>P4\/mmm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 50 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Ru1212-e1459036268928.jpg\" rel=\"attachment wp-att-3441\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-full wp-image-3441\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/Ru1212-e1459036268928.jpg\" alt=\"Ru1212\" width=\"176\" height=\"235\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">In the case of the ruthenocuprate compound,\u00a0RuSr<sub>2<\/sub>GdCu<sub>2<\/sub>O<sub>8<\/sub>, the structure contains a type I reservoir SrO\u2013RuO<sub>2<\/sub>\u2013SrO, where the Cu<sup>+2<\/sup>O chain layer is replaced by a\u00a0Ru<sup>+5<\/sup>O<sub>2<\/sub> layer, and Y<sup>+3<\/sup> is replaced by Gd<sup>+3<\/sup>. Taking the\u00a0Ru charge state to be +5 in this material, and given\u00a0the charge equivalence of Bi<sup>+3<\/sup>O<sup>\u22122<\/sup> and Ru<sup>+5<\/sup>(O<sup>\u20132<\/sup>)<sub>2<\/sub>, one can\u00a0draw an analogy with the Bi\/Pb compounds,\u00a0and approximate \u03c3. \u00a0In this case, however, there is only\u00a0one layer that is charge equivalent. \u00a0Thus, from rule (2a), one factor of 1\/2 is introduced arising from the valency scaling between Ru<sup>+5<\/sup>(O<sup>\u20132<\/sup>)<sub>2<\/sub> and Cu<sup>+2<\/sup>O, \u00a0Given that the Pauling <span style=\"color: #ff0000;\">electronegativity<\/span>\u00a0(see discussion of Bi-2212 in Ref. [2]) of Ru is 2.20, which is significantly greater than that of Cu (\u03c7 = 1.90), charge transfer aling the hard axis is suppressed, invoking an additional factor of 1\/2, such that [1,2]\n<ul>\n<li>Type I reservoir: SrO-RuO<sub>2<\/sub>-SrO<\/li>\n<li>Type II reservoir:\u00a0CuO<sub>2<\/sub>-Gd-CuO<sub>2<\/sub><\/li>\n<li>\u03c3 = (1\/2)(1\/2) \u03c3<sub>0<\/sub>\u00a0= 0.25 \u03c3<sub>0<\/sub><\/li>\n<li>\u03b7 = 2;\u00a0\u03bd=2<\/li>\n<li><em>A<\/em> = 14.7372 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 2.1820 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 50.28 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<li>D. R. Harshman and A. T. Fiory,\u00a0<a href=\"https:\/\/doi.org\/10.1016\/j.jpcs.2015.04.019\">J. Phys. Chem. Solids\u00a0<strong>85<\/strong>, 106 (2015)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#Ln(OF)FeAs\" name=\"Ln(OF)FeAs\"><\/a><\/p>\n<hr \/>\n<p><strong>(Ln\/Th)(O<sub>x\u2013y<\/sub>F<sub>1\u2013x<\/sub>)FeAs<\/strong> (<em>P4\/nmm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 26 K \u2013 55 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/LnOFFeAs.png\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2542 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/LnOFFeAs.png\" alt=\"Ln(O,F)FeAs\" width=\"198\" height=\"218\" srcset=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/LnOFFeAs.png 198w, http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/LnOFFeAs-136x150.png 136w\" sizes=\"auto, (max-width: 198px) 100vw, 198px\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">In the (n-type) Ln\u2013O\/F\u2013Fe\u2013As (Ln-1111) iron pnictides, e.g., La(O<sub>0.92\u2212y<\/sub>F<sub>0.08<\/sub>)FeAs (T<sub>C0<\/sub><sup>meas<\/sup> = 26 K),\u00a0Ce(O<sub>0.84\u2212y<\/sub>F<sub>0.16<\/sub>)FeAs (T<sub>C0<\/sub><sup>meas<\/sup> = 35 K), Tb(O<sub>0.80\u2212y<\/sub>F<sub>0.20<\/sub>)FeAs (T<sub>C0<\/sub><sup>meas<\/sup> = 45 K) and\u00a0Sm(O<sub>0.65 \u2212y<\/sub>F<sub>0.35<\/sub>)FeAs (T<sub>C0<\/sub><sup>meas<\/sup> = 55 K), where y accounts for the actual\u00a0O-site occupancy; we assume [x \u2212 x<sub>0<\/sub>] is given by F\u00a0stoichiometry, the Coulombic interaction is assumed to occur\u00a0between the Ln(O\/F) and AsFe layers, which defines \u03b6 (Ln\u2013As distance along the <em>c<\/em>-axis), and sets \u03b7 = \u03bd = 1 (i.e. within\u00a0the periodicity <em>d<\/em>). Applying rules (1b) (equally shared doping\u00a0between the hole and electron reservoirs) and (1a) (where the\u00a0doping is further divided between component layers of the two\u00a0reservoirs, [(O\/F)Ln and (AsFe)], one obtains \u03b3 = (1\/2)(1\/2) = (1\/4). \u00a0For Ln = Nd, see Ref. [2]. \u00a0For the\u00a0<span style=\"color: #ff0000;\">Th<sup>+4<\/sup><\/span> doped n-type 1111 iron pnictide compounds, such as\u00a0(Sm<sub>0.7<\/sub>Th<sub>0.3<\/sub>)OFeAs (T<sub>C0<\/sub><sup>meas<\/sup> = 51.5 K), the value of \u03c3 is given similarly, but with [x \u2212 x<sub>0<\/sub>] determined by the Th doping content. \u00a0Thus\u00a0one has\u00a0[1, 2]: [<span style=\"color: #ff0000;\">Need to recheck structure parameters<\/span>]\n<ul>\n<li>Type I reservoir:\u00a0\u00bd(Ln-2O\/F-Ln)<\/li>\n<li>Type II reservoir:\u00a0\u00bd(As-2Fe-As)<\/li>\n<li>\u03c3 = (1\/2)(1\/2) [x\u00a0\u2013 x<sub>0<\/sub>]; for O-deficient (no F),\u00a0\u03c3 = (1\/2)(1\/2) (2) [x\u00a0\u2013 x<sub>0<\/sub>]<\/li>\n<li>\u03b7 = 1;\u00a0\u03bd = 1<\/li>\n<li><strong>NbFeAsO<sub>0.85-y<\/sub>:<\/strong> <em>A<\/em> = 15.5417 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.653 \u00c5;\u00a0T<sub>C0<\/sub><sup>calc<\/sup> = 52.42 K [2]<\/li>\n<li><strong>GdFeAsO<sub>0.85-y<\/sub>:<\/strong> <em>A<\/em> = 15.1399 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.616 \u00c5;\u00a0T<sub>C0<\/sub><sup>calc<\/sup> = 54.33 K [2]<\/li>\n<li><strong>La(O<sub>0.92\u2212y<\/sub>F<sub>0.08<\/sub>)FeAs:<\/strong>\u00a0<em>A<\/em>\u00a0= 16.1620 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.7677 \u00c5;\u00a0T<sub>C0<\/sub><sup>calc<\/sup> = 24.82 K<\/li>\n<li><strong>Ce(O<sub>0.84\u2212y<\/sub>F<sub>0.16<\/sub>)FeAs:<\/strong>\u00a0<em>A<\/em>\u00a0= 15.8778 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.6819 \u00c5;\u00a0T<sub>C0<\/sub><sup>calc<\/sup> = 37.23 K<\/li>\n<li><strong>Tb(O<sub>0.80\u2212y<\/sub>F<sub>0.20<\/sub>)FeAs:<\/strong>\u00a0<em>A<\/em>\u00a0= 14.8996 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.5822 \u00c5;\u00a0T<sub>C0<\/sub><sup>calc<\/sup> = 45.67 K<\/li>\n<li><strong>Nb(O<sub>0.70-y<\/sub>F<sub>0.30<\/sub>)FeAs:<\/strong> <em>A<\/em> = 15.626\u00a0\u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.653 \u00c5;\u00a0T<sub>C0<\/sub><sup>calc<\/sup> = 52.28 K [2]<\/li>\n<li><strong>Sm(O<sub>0.65\u2212y<\/sub>F<sub>0.35<\/sub>)FeAs:<\/strong>\u00a0<em>A<\/em>\u00a0= 15.4535 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.6670 \u00c5;\u00a0T<sub>C0<\/sub><sup>calc<\/sup> = 56.31 K<\/li>\n<li><strong>(Sm<sub>0.7<\/sub>Th<sub>0.3<\/sub>)OFeAs:<\/strong>\u00a0<em>A<\/em>\u00a0= 15.4897 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.6710 \u00c5;\u00a0T<sub>C0<\/sub><sup>calc<\/sup> = 51.94 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<li>D. R. Harshman and A. T. Fiory.\u00a0<span style=\"color: #ff0000;\">preprint<\/span>\u00a0(2021).<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"#BaFe2As2\" name=\"BaFe2As2\"><\/a><\/p>\n<hr \/>\n<p><strong>(Ba\/K)(Fe\/Co)<sub>2<\/sub>As<sub>2<\/sub><\/strong> (<em>I4\/mmm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 37 K &amp; 22 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/BaFe2As2.png\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2567 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/BaFe2As2.png\" alt=\"BaFe2As2\" width=\"206\" height=\"260\" srcset=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/BaFe2As2.png 206w, http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/BaFe2As2-119x150.png 119w\" sizes=\"auto, (max-width: 206px) 100vw, 206px\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">As in the case of the 1111 structures, rules (1a) and (1b) also apply in determining \u03b3 for the 122<span style=\"color: #ff0000;\">\u00a0<\/span>compounds, e.g., (Ba<sub>0.6<\/sub>K<sub>0.4<\/sub>)Fe<sub>2<\/sub>As<sub>2<\/sub>\u00a0and Ba(Fe<sub>1.84<\/sub>Co<sub>0.16<\/sub>)As<sub>2<\/sub>, except that the doping is also shared between\u00a0the two FeAs structures [rule (1a)] yielding an additional\u00a0factor of 1\/2 such that \u03b3 = (1\/2)(1\/2)(1\/2)\u00a0= 0.125. \u00a0For (Ba<sub>0.6<\/sub>K<sub>0.4<\/sub>)Fe<sub>2<\/sub>As<sub>2<\/sub> (T<sub>C0<\/sub><sup>meas<\/sup>\u00a0= 37 K, x = 0.4 and x<sub>0<\/sub> = 0), the Coulombic interaction occurs between the Ba\/K layer and\u00a0the two adjacent Fe<sup>+2<\/sup>As<sup>\u20133<\/sup> structures, where\u00a0we designate the Ba(K) layers as\u00a0type II ( \u03b7 = 1), which interact with the As in the FeAs type I (\u03bd = 2) structures. The \u03b3 factor for the <span style=\"color: #ff0000;\">n-type<\/span>\u00a0homologue to the above <span style=\"color: #ff0000;\">p-type<\/span> compound, Ba(Fe<sub>1.84<\/sub>Co<sub>0.16<\/sub>)As<sub>2<\/sub> (T<sub>C0<\/sub><sup>meas<\/sup>\u00a0= 22 K, x = 0.16 and x<sub>0<\/sub>\u00a0= 0),\u00a0is similarly calculated, but with [x \u2212 x<sub>0<\/sub>] corresponding to Co doping. Therefore [1]:<\/p>\n<ul>\n<li>Type I reservoir:\u00a0As-2(Fe\/Co)-As<\/li>\n<li>Type II reservoir: Ba\/K<\/li>\n<li>\u03c3 = (1\/2)(1\/2)(1\/2) [x \u2212 x<sub>0<\/sub>]<\/li>\n<li>\u03b7 = 1; \u03bd = 2<\/li>\n<li><strong>(Ba<sub>0.6<\/sub>K<sub>0.4<\/sub>)Fe<sub>2<\/sub>As<sub>2<\/sub>:<\/strong> <em>A<\/em> = 15.2803 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.932 \u00c5; T<sub>C0<\/sub><sup>calc<\/sup> = 36.93 K<\/li>\n<li><strong>Ba(Fe<sub>1.84<\/sub>Co<sub>0.16<\/sub>)As<sub>2<\/sub>:<\/strong> <em>A<\/em> = 15.6848 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.8920 \u00c5; T<sub>C0<\/sub><sup>calc<\/sup> = 23.54 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"FeSe\" name=\"FeSe\"><\/a><\/p>\n<hr \/>\n<p><strong>FeSe<sub>0.977<\/sub> (7.5 GPa)<\/strong>\u00a0(<em>Pnnm<\/em>, T<sub>C0<\/sub><sup>meas<\/sup> = 36.5 K) [Check structure information]<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/FeSe.png\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2580 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/FeSe.png\" alt=\"FeSe\" width=\"268\" height=\"202\" srcset=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/FeSe.png 268w, http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/FeSe-199x150.png 199w, http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/FeSe-150x113.png 150w\" sizes=\"auto, (max-width: 268px) 100vw, 268px\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">While superconducting (tetragonal) Fe<sub>1+x<\/sub>Se<sub>1\u2212y<\/sub> is very nearly\u00a0stoichiometric, some degree of symmetry breaking, arising from either a Se deficiency or an excess in Fe content,\u00a0must exist to induce the superconducting condensate. It is\u00a0also clear that the optimal superconducting state is achieved\u00a0at a hydrostatically applied pressure of 7.5 \u2013 8.5 GPa,\u00a0which we attribute to pressure-induced charge redistribution,\u00a0analogous to the response of YBa<sub>2<\/sub>Cu<sub>4<\/sub>O<sub>8<\/sub>.\u00a0Although assigning reservoir types to the Fe and Se layers is\u00a0somewhat subjective, it is also not a necessary requirement\u00a0in determining \u03c3 (for convention, we refer to the negative\u00a0valence Se layer as type I). Given\u00a0the +2 and \u22122 valences of Fe and Se, respectively, the charge\u00a0doping is 2x or 2y (or, typically, the sum thereof), where x and\u00a0y are small and positive quantities. High resistivity (\u223c33 m\u03a9cm at T \u223c 9 K) observed confirms that stoichiometric FeSe is dominantly a\u00a0non-metallic material. One may therefore assume that the FeSe\u00a0binary compound of precisely 1:1 stoichiometry is effectively\u00a0an insulating material and that doping is achieved by\u00a0introducing excess Fe or depleted Se. From rule (1b) the\u00a0dopant charge populates both charge reservoirs, yielding \u03b3 =\u00a01\/2. \u00a0For FeSe<sub>0.977<\/sub> (y = 0.023, y<sub>0<\/sub> = 0), the doping factor has the single term [2(y\u2212y<sub>0<\/sub>)] = 2(0.023) and the\u00a0fractional charge is then calculated to be \u03c3 = 2(0.023)\/2 =\u00a00.023. \u00a0The basal-plane lattice parameter\u00a0at 7.5 GPa is <em>a<\/em> = 3.622 A.\u00a0\u00a0The interaction distance \u03b6 is measured between nearest-neighbor Fe and Se ions observed at the same pressure. \u00a0Thus one has [1]:<\/p>\n<ul>\n<li>Type I reservoir:\u00a0Se<sub>0.977<\/sub><\/li>\n<li>Type II reservoir:\u00a0Fe<sub>1.0<\/sub><\/li>\n<li>\u03c3 = (1\/2) [2(y \u2212 y<sub>0<\/sub>)] = 0.023<\/li>\n<li>\u03b7 = 1; \u03bd = 1<\/li>\n<li><em>A<\/em> = 13.1189 \u00c5<sup>2<\/sup>;\u00a0\u03b6 = 1.4240 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 36.68 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman and A. T. Fiory,\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/24\/13\/135701\">J. Phys.: Condens. Matt.\u00a0<strong>24<\/strong>, 135701 (2012)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"FeSeTe\" name=\"FeSeTe\"><\/a><\/p>\n<hr \/>\n<p><strong>Fe<sub>1.03<\/sub>Se<sub>0.57<\/sub>Te<sub>0.43<\/sub> (2.3 GPa)<\/strong> (T<sub>C0<\/sub><sup>meas<\/sup> = 23.3 K) [<span style=\"color: #ff0000;\">Check structure information<\/span>]<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/FeSeTe.png\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2596 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/FeSeTe.png\" alt=\"FeSeTe\" width=\"252\" height=\"298\" srcset=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/FeSeTe.png 252w, http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/FeSeTe-127x150.png 127w\" sizes=\"auto, (max-width: 252px) 100vw, 252px\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">To calculate \u03c3 for Fe<sub>1+x<\/sub>Se<sub>1\u2013y<\/sub>Te<sub>y<\/sub>\u00a0system (for y &gt; 0.3), one must\u00a0consider the type I reservoir structure to be Te<sub>y<\/sub>\u2013Fe<sub>x<\/sub>\u2013Se<sub>1\u2212y<\/sub>,\u00a0where \u03bd = 2 and the charge doping, supplied by the excess\u00a0Fe<sup>+2<\/sup> ions (two charges per excess Fe cation), is shared equally between the Te<sub>y<\/sub> and Se<sub>1\u2212y<\/sub> layers,\u00a0with comparable occupancies since y \u223c 1\/2. \u00a0The result for \u03b3\u00a0is a factor of 1\/2 from rule (1a), multiplied by an additional factor\u00a0of 1\/2 associated with rule (1b), yielding \u03b3 = 1\/4. Since accurate information on Fe stoichiometry is\u00a0essential, we consider results reported for a sample\u00a0with composition Fe<sub>1.03<\/sub>Se<sub>0.57<\/sub>Te<sub>0.43<\/sub>, where x \u2248 0.03 was\u00a0obtained from pressure- and temperature-dependent Rietveld\u00a0refinements of synchrotron x-ray powder diffraction data. The\u00a0sample under study exhibited superconducting transitions\u00a0(determined from magnetization onsets) of 13.9 K at ambient\u00a0pressure, reaching a maximum T<sub>C<\/sub> = 23.3 K under hydrostatic\u00a0pressure of 2.3 GPa. Unfortunately, only resistance and\u00a0zero-field-cooled magnetization data are given, limiting our\u00a0ability to quantify the sample\u2019s quality. \u00a0In another work on\u00a0an FeSe<sub>0.5<\/sub>Te<sub>0.5<\/sub> sample (in this case Fe stoichiometry of\u00a0unity was apparently presumed, leaving \u03c3 undetermined), the\u00a0superconducting transitions (onset values) varyd from 13.5 K\u00a0at ambient pressure, reaching a maximum T<sub>C<\/sub> of ~25\u201326 K\u00a0(26.2 K reported) at 2 GPa. \u00a0The sample in this case was\u00a0judged by the authors to be of high quality, based on a 12%\u00a0Meissner fraction (the field-cooled magnetization is about\u00a038% of the zero-field-cooled magnetization; normal-state\u00a0resistivity is 1.4 m\u03a9cm extrapolated to T<sub>C<\/sub> at 2 GPa). \u00a0Since one does not expect the structural parameters to differ\u00a0greatly between these two samples, it would normally be\u00a0reasonable to accept 25.5 K as representative of the highest\u00a0T<sub>C<\/sub> attained for this compound. \u00a0Given that the Fe content\u00a0is unknown for the latter, results from the former are adopted for doping and T<sub>C0<\/sub><sup>meas<\/sup>, with the understanding that the quoted transition\u00a0temperature may be lower than optimum. \u00a0To calculate T<sub>C0<\/sub>\u00a0for the Fe<sub>1.03<\/sub>Se<sub>0.57<\/sub>Te<sub>0.43<\/sub> compound, we use data taken at 2.0 GPa; <em>a<\/em> = 3.7317 and <em>b<\/em> = 3.7262 \u00c5, giving a plane area (per formula unit) of <em>A<\/em> = 13.9051 \u00c5<sup>2<\/sup>. \u00a0One further estimates an average interaction distance \u3008\u03b6\u3009 = 1.597 \u00c5\u00a0(assuming the measurement reflects an average between \u03b6<sub>Se<\/sub> and \u03b6<sub>Te<\/sub>). \u00a0This value is corroborated elsewhere, which indicates \u03b6<sub>Te<\/sub>\u00a0= 1.7638 \u00c5\u00a0and \u03b6<sub>Se<\/sub> = 1.4162 \u00c5 for a sample\u00a0indicates \u03b6<sub>Te<\/sub> = 1.7638 A\u00a0under pressure (presumably 2.0 GPa), corresponding to an average value \u3008\u03b6\u3009 = 1.59 \u00c5. Using \u3008\u03b6\u3009 takes into account disorder in site occupancy and interactions contributed by\u00a0the further Te ion, given that (\u03b6<sub>Te<\/sub> \u2212 \u03b6<sub>Se<\/sub>) &lt;&lt;\u001c \u3008\u03b6\u3009. \u00a0Above\u00a0\u223c2.5 GPa, the compound undergoes an orthorhombic\u00a0to monoclinic transition, resulting in small abrupt changes to\u00a0some of the relevant lattice parameters.<\/p>\n<ul>\n<li>Type I reservoir:\u00a0Se<sub>0.57<\/sub>-Fe<sub>0.03<\/sub>-Te<sub>0.43<\/sub><\/li>\n<li>Type II reservoir:\u00a0Fe<sub>1.0<\/sub><\/li>\n<li>\u03c3 = (1\/2) (1\/2) [2(1.03\u00a0\u2013 1)] = 0.015<\/li>\n<li>\u03b7 = 1; \u03bd = 2<\/li>\n<li><em>A<\/em> = 13.9051 \u00c5<sup>2<\/sup>; \u3008\u03b6\u3009 = 1.5970 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 25.65 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman and A. T. Fiory,\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/24\/13\/135701\">J. Phys.: Condens. Matt.\u00a0<strong>24<\/strong>, 135701 (2012)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"AFe2Se2\" name=\"AFe2Se2\"><\/a><\/p>\n<hr \/>\n<p><strong>A<sub>z<\/sub>Fe<sub>2-x<\/sub>Se<sub>2<\/sub><\/strong> (T<sub>C0<\/sub><sup>meas<\/sup> = 28.5 \u2013 31.5 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/AFe2Se2.png\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2609 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/AFe2Se2.png\" alt=\"AFe2Se2\" width=\"208\" height=\"298\" srcset=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/AFe2Se2.png 208w, http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/AFe2Se2-105x150.png 105w\" sizes=\"auto, (max-width: 208px) 100vw, 208px\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">Unlike Fe<sub>1+x<\/sub>Se<sub>1\u2212y<\/sub>, the ternary A<sub>z<\/sub>Fe<sub>2\u2212x<\/sub>Se<sub>2<\/sub> series of\u00a0compounds can be optimized at ambient pressure, and are characterized by a rather large normal-state\u00a0resistivity at T<sub>C<\/sub>, signifying a higher scattering rate. For\u00a0these materials, the type I reservoir structures are identified\u00a0as the Se\u2013Fe<sub>2\u2212x<\/sub>\u2013Se triple layers, with \u03bd = 2, and the\u00a0alkali metal A<sub>z<\/sub> layers are defined as the type II (\u03b7 = 1)\u00a0reservoir structures (the exact formula-unit structure that\u00a0we consider is Fe<sub>1\u2212x\/2<\/sub>\u2013Se\u2013Az\u2013Se\u2013Fe<sub>1\u2212x\/2<\/sub>, or equivalently\u00a0A<sub>z\/2<\/sub>\u2013Se\u2013Fe<sub>2\u2212x<\/sub>\u2013Se\u2013A<sub>z\/2<\/sub> , the latter corresponding to figure 1(b) in Ref. [1]). There are generally two doping sources; one\u00a0associated with the type I reservoir and the other with the\u00a0type II. The two terms in equation (2) are [z<sub>0<\/sub> \u2212 z] and\u00a0+2[x<sub>0<\/sub> \u2212 x] for A<sub>z<\/sub> and Fe<sub>2\u2212x<\/sub>, respectively, where the prefactor\u00a0of 2 corresponds to the double valence of Fe (the terms\u00a0v<sub>i<\/sub> (x \u2212 x<sub>0<\/sub>)<sub>i<\/sub> for the two reservoir types have opposite signs).\u00a0There also appear to be (at least) two insulating end materials\u00a0corresponding to the alkali metal and iron components\u00a0(determined for A = K): KFe<sub>2<\/sub>Se<sub>2<\/sub> such that z<sub>0<\/sub> = 1, and\u00a0KFe<sub>2\u2212x<sub>0<\/sub><\/sub>Se<sub>2<\/sub>, where 0.40 \u2264 x<sub>0<\/sub> \u2264 0.42. Since x and z\u00a0depend on growth stoichiometries, these two doping sources\u00a0generally provide unequal contributions to the fractional\u00a0charge, which is found by combining the magnitudes of the\u00a0two charges as per equation (2), and treating doping as if from\u00a0a single source. Thus, by analogy with (Ba<sub>1\u2212x<\/sub>K<sub>x<\/sub>)Fe<sub>2<\/sub>As<sub>2<\/sub>, the\u00a0charge allocation rules (1a) and (1b) apply. Here, one factor\u00a0of 1\/2 arises from rule (1b) requiring that the doping charge\u00a0be shared between the two reservoirs; the factor of (1\/2)(1\/2)\u00a0arises from dividing the charge among the four individual\u00a0layers of the two Fe\u2013Se structures of the type I reservoir (rule\u00a0(1a) for N = 4, or applied twice with N = 2). From this we\u00a0can write \u03b3 = (1\/2)(1\/2)(1\/2) = 0.125. Thus one has [1]:<\/p>\n<ul>\n<li>Type I reservoir:\u00a0Se-Fe<sub>2-x<\/sub>-Se<\/li>\n<li>Type II reservoir:\u00a0A<sub>z<\/sub><\/li>\n<li>\u03c3 = (1\/2) (1\/2) (1\/2) [(1\u00a0\u2013 z) + 2(0.40 \u2013 x)]<\/li>\n<li>\u03b7 = 1; \u03bd = 2<\/li>\n<li><strong>K<sub>0.83<\/sub>Fe<sub>1.66<\/sub>Se<sub>2<\/sub>:<\/strong>\u00a0<em>A<\/em> = 15.2432 \u00c5<sup>2<\/sup>; \u3008\u03b6\u3009 = 2.0241 \u00c5;\u00a0T<sub>C0<\/sub><sup>meas<\/sup> = 29.5 K; T<sub>C0<\/sub><sup>calc<\/sup> = 30.07 K<\/li>\n<li><strong>Rb<sub>0.83<\/sub>Fe<sub>1.70<\/sub>Se<sub>2<\/sub>:<\/strong>\u00a0<em>A<\/em> = 15.4867 \u00c5<sup>2<\/sup>; \u3008\u03b6\u3009 = 2.1463 \u00c5;\u00a0T<sub>C0<\/sub><sup>meas<\/sup> = 31.5 K; T<sub>C0<\/sub><sup>calc<\/sup> = 31.78 K<\/li>\n<li><strong>Cs<sub>0.83<\/sub>Fe<sub>1.71<\/sub>Se<sub>2<\/sub>:<\/strong>\u00a0<em>A<\/em> = 16.1419 \u00c5<sup>2<\/sup>; \u3008\u03b6\u3009 = 2.3298 \u00c5;\u00a0T<sub>C0<\/sub><sup>meas<\/sup> = 28.5 K; T<sub>C0<\/sub><sup>calc<\/sup> = 29.44 K<\/li>\n<\/ul>\n<ol style=\"text-align: justify;\">\n<li>D. R. Harshman and A. T. Fiory,\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/24\/13\/135701\">J. Phys.: Condens. Matt.\u00a0<strong>24<\/strong>, 135701 (2012)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"Ax(S)yTiNCl\" name=\"Ax(S)yTiNCl\"><\/a><\/p>\n<hr \/>\n<p><strong>Na<sub>0.16<\/sub>(<em>S<\/em>)<sub>y<\/sub>TiNCl<\/strong>\u00a0(<em>S<\/em> = PC, BC ) (T<sub>C0<\/sub><sup>meas<\/sup>\u00a0~ <span style=\"color: #ff6600;\">6\u00a0\u2013 8 K<\/span>)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/alpha-TiNCl.png\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2643 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/alpha-TiNCl.png\" alt=\"alpha-TiNCl\" width=\"160\" height=\"298\" srcset=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/alpha-TiNCl.png 160w, http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/alpha-TiNCl-81x150.png 81w\" sizes=\"auto, (max-width: 160px) 100vw, 160px\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">High-T<sub>C<\/sub> superconductivity in this model occurs in layered\u00a0structures forming adjacent type-I and type-II charge reservoir\u00a0layers containing the superconducting and mediating charges,\u00a0respectively, repeating alternately along the transverse axis.\u00a0The superconducting transition temperature depends on the spatially indirect Coulomb interaction across the transverse\u00a0distance \u03b6 between the two charge reservoirs, measured\u00a0between the outer chlorines in the type-I [TiNCl]<sub>2<\/sub> layer and the\u00a0locus of the cations <em>A<\/em><sub>x<\/sub> in the neighboring type-II intercalation\u00a0layer, assuming co-intercalant (<em>S<\/em>)<sub>y<\/sub> is uncharged. The layered structure of <em>A<\/em><sub>x<\/sub>(<em>S<\/em>)<sub>y<\/sub>TiNCl is characterized by a thickness <em>d<\/em><sub>2<\/sub> of\u00a0the [TiNCl]<sub>2<\/sub> layers, the transverse spacing d between them,\u00a0and an intercalant thickness <em>d<\/em> \u2212 <em>d<\/em><sub>2<\/sub>. Assuming that the\u00a0mean cation <em>A<\/em><sub>x<\/sub> locus is at the intercalant-layer midplane, the\u00a0interaction distance is \u03b6 = (<em>d<\/em> \u2212 <em>d<\/em><sub>2<\/sub>)\/2. Since <em>d<\/em><sub>2<\/sub> is approximately the same as for pristine \u03b1-TiNCl (see [1] of Ref. [1]), the observed\u00a0functional dependence of T<sub>C<\/sub> on d is expected to correlate\u00a0with an analogous dependence on \u03b6 . However, one notes\u00a0that the interlayer interaction length is the shorter distance\u00a0\u03b6, rather than the spacing d. Structural and superconductivity\u00a0data are presented in Table I, listing directly measured values\u00a0of <em>d<\/em><sub>2<\/sub> where available. The Coulomb energy e<sup>2<\/sup>\/\u03b6 lies within\u00a01.8 \u2013 8.7 eV.\u00a0For\u00a0<em>A<\/em><sub>x<\/sub>(<em>S<\/em>)<sub>y<\/sub>TiNCl, doping occurs only in the intercalation layer\u00a0via <em>A<\/em><sub>x<\/sub> such that \u03c3 is determined according to the simplified\u00a0relation,\u00a0\u03c3 = \u03b3\u00a0|v(x \u2212 x<sub>0<\/sub>)|,\u00a0where v is the valence and x is the optimal content of the\u00a0cation dopant species in the type II <em>A<\/em><sub>x<\/sub>(S)<sub>y<\/sub> reservoir; x<sub>0<\/sub> is\u00a0the threshold value of x for superconductivity; here, v = 1\u00a0for alkali-ion doping and x<sub>0<\/sub> = 0 is inferred elsewhere.\u00a0The factor \u03b3 derives from the allocation of the dopant by\u00a0considering a given compound\u2019s structure. Following the\u00a0procedure generally applied to high-T<sub>C<\/sub> superconductors, the\u00a0charge introduced by the dopant is shared equally between\u00a0the two charge reservoirs [rule (1b)]. Additionally, the methodology\u00a0requires the doped charge to be distributed pairwise between\u00a0the charge-carrying layer types within each of the charge\u00a0reservoirs. Assuming the co-intercalant contributes no doping\u00a0charge, determination of \u03b3 for <em>A<\/em><sub>x<\/sub>(S)<sub>y<\/sub>TiNCl is comparable\u00a0to that of (Ba<sub>0.6<\/sub>K<sub>0.4<\/sub>)Fe<sub>2<\/sub>As<sub>2<\/sub> for which a structural analogy\u00a0was previously noted. Sharing the charge equally between\u00a0the two reservoirs contributes a factor of 1\/2 to \u03b3 . Sharing\u00a0between the Cl layer and the double-TiN-layered structure and\u00a0then to the two TiN layers contributes two factors from rule (1a) of 1\/2 to\u00a0\u03b3. Hence, \u03b3 = (1\/2)(1\/2)(1\/2) = 1\/8, yielding \u03c3 generally\u00a0smaller than x. Thus, one has\u00a0[1,2]:<\/p>\n<ul>\n<li>Type I reservoir:\u00a0TiNCl<\/li>\n<li>Type II reservoir:\u00a0<em>A<\/em><sub>x<\/sub>(<em>S<\/em>)<sub>y<\/sub><\/li>\n<li>\u03c3 = (1\/2) (1\/2) (1\/2) [x<sub>opt<\/sub>]<\/li>\n<li>\u03b7 = 1; \u03bd = 2<\/li>\n<li><strong><strong>Na<sub>0.16<\/sub>(PC)<sub>y<\/sub>TiNCl<\/strong>:<\/strong>\u00a0<em>A<\/em> = 13.0331 \u00c5<sup>2<\/sup>; \u03b6 = 7.6735 \u00c5;\u00a0T<sub>C0<\/sub><sup>meas<\/sup> = 7.4 K; T<sub>C0<\/sub><sup>calc<\/sup> = 6.37 K<\/li>\n<li><strong><strong>Na<sub>0.16<\/sub>(BC)<sub>y<\/sub>TiNCl<\/strong>:<\/strong>\u00a0<em>A<\/em> = 13.0331 \u00c5<sup>2<\/sup>; \u03b6 = 7.7803 \u00c5;\u00a0T<sub>C0<\/sub><sup>meas<\/sup> = 6.9 K; T<sub>C0<\/sub><sup>calc<\/sup> = 6.28 K<\/li>\n<\/ul>\n<ol>\n<li>D. R. Harshman and A. T. Fiory, <a href=\"https:\/\/doi.org\/10.1103\/PhysRevB.90.186501\">Phys. Rev. B <strong>90<\/strong>, 186501 (2014)<\/a>.<\/li>\n<li>D. R. Harshman and A. T. Fiory, <a href=\"https:\/\/doi.org\/10.1007\/s10948-015-3147-x\">J. Supercond. Nov. Magn. <strong>28<\/strong>, 2967 (2015)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"Ax(S)yZrNCl\" name=\"Ax(S)yZrNCl\"><\/a><\/p>\n<hr \/>\n<p><strong>Li<sub>x<\/sub>(<em>S<\/em>)<sub>y<\/sub>ZrNCl<\/strong> (T<sub>C0<\/sub><sup>meas<\/sup>\u00a0= 13.7 &amp; 15.1 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/beta-MNX.png\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2645 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/beta-MNX.png\" alt=\"beta-MNX\" width=\"139\" height=\"297\" srcset=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/beta-MNX.png 139w, http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/beta-MNX-70x150.png 70w\" sizes=\"auto, (max-width: 139px) 100vw, 139px\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">The exemplary compound is \u03b2-Li<sub>x<\/sub>ZrNCl,\u00a0for which optimal stoichiometry is identified as occurring at\u00a0x<sub>opt<\/sub> = 0.08 at which point the full superconducting volume\u00a0is reached and T<sub>C<\/sub> (= 15.1 K) is maximized (see [19, 20] of Ref. [1]). Underdoping occurs for x &lt; 0.08, as identified by diminished\u00a0superconducting volumes that vanish for x &lt; 0.05 [19],\u00a0indicating x<sub>0<\/sub> = 0.05. Muon-spin-depolarization rates \u03c3<sub>\u03bc<\/sub>(T \u2192 0)\u00a0for Li<sub>x<\/sub>ZrNCl are linear in (x \u2212 x<sub>0<\/sub>) with x<sub>0<\/sub> = 0.05 obtained\u00a0by extrapolation (see [51] in Ref. [1]; also, plasma frequency data show that\u00a0\u03c9<sub>p<\/sub><sup>2<\/sup> extrapolates to zero for x \u2248 x<sub>0<\/sub>\u00a0(see [46] in Ref. [1]. Signature characteristics of overdoping occur for x &gt; x<sub>opt<\/sub> in that T<sub>C<\/sub> is\u00a0a decreasing function of x, falling off precipitously from\u00a015.1 K for x between 0.08 and 0.2 and reaching a minimum of about 11.5 K for 0.2 &lt; x &lt; 0.4 (see [19, 47] in Ref. [1]). This negates the\u00a0notion of the superfluid density being a dominant factor in\u00a0determining T<sub>C<\/sub> in the overdoped regime, as suggested elsewhere [15]. Continuous incorporation of Li and charge doping have\u00a0been concluded from an x dependence in certain Raman\u00a0modes, particularly for in-plane vibrations of the [ZrNCl]<sub>2<\/sub>\u00a0block (mode denoted \u201cA\u201d in (see [19] of Ref. [1]). Within this x variation, the underdoping and overdoping regimes appear to be\u00a0reflected in the x dependence of the lattice parameters (see [19] of Ref. [1]).\u00a0The lattice parameter <em>c<\/em> is particularly sensitive to the intercalant thickness and dictated to a significant extent by the\u00a0Li\u2013Cl bond length that determines \u03b6, since\u00a0<em>d<\/em> is given by c\/3 while the [ZrNCl]<sub>2<\/sub> thickness <em>d<\/em><sub>2<\/sub> tends to\u00a0show little variation with intercalation. The variation of <em>c<\/em> vs.\u00a0x is strongest at low x and crosses over to a weaker dependence for x greater than about 0.1, which is rather close to\u00a0the optimal doping point x<sub>opt<\/sub>. This behavior suggests that\u00a0participating charges are introduced into the interaction layers for x \u2264 x<sub>opt<\/sub> with the equilibrium charge structure of the Li\u2013Cl interaction layers fully formed at x = x<sub>opt<\/sub>. For\u00a0x &gt; x<sub>opt<\/sub>, the excess charges are transferred to the [ZrNCl]<sub>2<\/sub>\u00a0reservoir, yielding weak variation of intercalant thickness\u00a0with the further increases in x. This non-participating charge\u00a0fraction, being more localized in the [ZrN]<sub>2<\/sub> structures and\u00a0minimally affecting the Cl sites, is assumed benign with\u00a0respect to the superconducting pairing interaction. A similar change in slope is revealed in the careful measurements\u00a0of \u03c9<sub>p<\/sub><sup>2<\/sup> vs. x, which nearly coincide with results from first\u00a0principles calculations of band structure [46]. In addition,\u00a0the damping \u0002\u03c4<sup>\u22121<\/sup> is reported to be greater for x &gt; x<sub>opt<\/sub>\u00a0containing non-participating charge. Also reported in (see [35] in Ref. [1]) is the compound Zn<sub>0.04<\/sub>ZrNCl, with T<sub>C<\/sub> = 15 K, which is possibly a\u00a0divalent doping analogue of Li<sub>0.08<\/sub>ZrNCl. The corresponding co-intercalated\u00a0compound, Li<sub>0.13<\/sub>(DMF)<sub>y<\/sub>ZrNCl (where DMF is (N, N)-dimethyl-formamide, C<sub>3<\/sub>H<sub>7<\/sub>NO), with T<sub>C<\/sub><sup>meas<\/sup> = 13.7 K (see [7] in Ref. [1]), was also found to be optimal [1]. \u00a0As in the case of the related TiNCl compounds, \u03b6 = (<em>d<\/em> \u2013 <em>d<\/em><sub>2<\/sub>)\/2 [1] and \u03c3 = \u03b3\u00a0|v[x<sub>opt<\/sub> \u2013 x<sub>0<\/sub>]|. \u00a0The \u03b3 factor is similarly obtained as well; a factor of (1\/2) is given by rule (1b), and an additional two factors of (1\/2) arises from the pairwise sharing between the Cl layer and the double-TiN-layered structure and\u00a0then to the two TiN layers, such that \u03b3 = (1\/2)(1\/2)(1\/2) = 1\/8. \u00a0Thus [1]:<\/p>\n<ul>\n<li>Type I reservoir:\u00a0ZrNCl<\/li>\n<li>Type II reservoir:\u00a0Li<sub>x<\/sub>(<em>S<\/em>)<sub>y<\/sub><\/li>\n<li>note hexagonal structure<\/li>\n<li>\u03c3 = (1\/2) (1\/2) (1\/2) |v [x<sub>opt<\/sub> \u2013 x<sub>0<\/sub>]|; v =1 for Li<\/li>\n<li>\u03b7 = 1; \u03bd = 2<\/li>\n<li><strong>Li<sub>0.08<\/sub>ZrNCl:<\/strong>\u00a0x<sub>0<\/sub> = 0.05;\u00a0<em>A<\/em> = 11.3233 \u00c5<sup>2<\/sup>; \u03b6 = 1.5817 \u00c5;\u00a0T<sub>C0<\/sub><sup>calc<\/sup> = 14.35 K<\/li>\n<li><strong>Li<sub>0.13<\/sub>(DMF)<sub>y<\/sub>ZrNCl:<\/strong>\u00a0x<sub>0<\/sub> = 0;\u00a0<em>A<\/em> = 11.3233 \u00c5<sup>2<\/sup>; \u03b6 = 3.400 \u00c5;\u00a0T<sub>C0<\/sub><sup>calc<\/sup> = 13.90 K<\/li>\n<\/ul>\n<ol>\n<li>D. R. Harshman and A. T. Fiory, <a href=\"https:\/\/doi.org\/10.1007\/s10948-015-3147-x\">J. Supercond. Nov. Magn. <strong>28<\/strong>, 2967 (2015)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"Ax(S)yHfNCl\" name=\"Ax(S)yHfNCl\"><\/a><\/p>\n<hr \/>\n<p><strong><em>A<\/em><sub>x<\/sub>(<em>S<\/em>)<sub>y<\/sub>HfNCl<\/strong> (T<sub>C0<\/sub><sup>meas<\/sup>\u00a0= 20 \u2013 24 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/beta-MNX.png\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2645 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/beta-MNX.png\" alt=\"beta-MNX\" width=\"139\" height=\"297\" srcset=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/beta-MNX.png 139w, http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/beta-MNX-70x150.png 70w\" sizes=\"auto, (max-width: 139px) 100vw, 139px\" \/><\/a><\/p>\n<p>Calculation of \u03c3 utilizes the same methodology as is applied in the case of Li<sub>x<\/sub>(<em>S<\/em>)<sub>y<\/sub>ZrNCl.<\/p>\n<ul>\n<li>Type I reservoir:\u00a0HfNCl<\/li>\n<li>Type II reservoir:\u00a0<em>A<\/em><sub>x<\/sub>(<em>S<\/em>)<sub>y<\/sub><\/li>\n<li>note hexagonal structure<\/li>\n<li>\u03c3 = (1\/2) (1\/2) (1\/2) |v [x<sub>opt<\/sub> \u2013 x<sub>0<\/sub>]|; v = 1<\/li>\n<li>\u03b7 = 1; \u03bd = 2<\/li>\n<li><strong>Na<sub>0.25<\/sub>HfNCl:<\/strong>\u00a0x<sub>0<\/sub> = 0.15;\u00a0<em>A<\/em> = 11.1484 \u00c5<sup>2<\/sup>; \u03b6 = 1.6580 \u00c5;\u00a0T<sub>C0<\/sub><sup>calc<\/sup> = 25.19 K<\/li>\n<li><strong>Li<sub>0.2<\/sub>HfNCl:<\/strong>\u00a0x<sub>0<\/sub> = 0.15;\u00a0<em>A<\/em> = 11.1195 \u00c5<sup>2<\/sup>; \u03b6 = 31.5950 \u00c5; T<sub>C0<\/sub><sup>calc<\/sup> = 20.31 K<\/li>\n<li><strong>Li<sub>0.2<\/sub>(NH<sub>3<\/sub>)<sub>y<\/sub>HfNCl:<\/strong> x<sub>0<\/sub> = 0;\u00a0<em>A<\/em> = 11.1117 \u00c5<sup>2<\/sup>; \u03b6 = 2.7620 \u00c5;\u00a0T<sub>C0<\/sub><sup>calc<\/sup> = 21.42 K<\/li>\n<li><strong>Ca<sub>0.11<\/sub>(NH<sub>3<\/sub>)<sub>y<\/sub>HfNCl:<\/strong> x<sub>0<\/sub> = 0;\u00a0<em>A<\/em> = 11.1251 \u00c5<sup>2<\/sup>; \u03b6 = 2.7370 \u00c5;\u00a0T<sub>C0<\/sub><sup>calc<\/sup> = 22.66 K<\/li>\n<li><strong>Eu<sub>0.08<\/sub>(NH<sub>3<\/sub>)<sub>y<\/sub>HfNCl:<\/strong> x<sub>0<\/sub> = 0;\u00a0<em>A<\/em> = 11.1117 \u00c5<sup>2<\/sup>; \u03b6 = 2.6690 \u00c5;\u00a0T<sub>C0<\/sub><sup>calc<\/sup> = 24.28 K<\/li>\n<\/ul>\n<ol>\n<li>D. R. Harshman and A. T. Fiory, <a href=\"https:\/\/doi.org\/10.1007\/s10948-015-3147-x\">J. Supercond. Nov. Magn. <strong>28<\/strong>, 2967 (2015)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"BEDT\" name=\"BEDT\"><\/a><\/p>\n<hr \/>\n<p style=\"text-align: justify;\"><strong>\u03ba\u2013[BEDT-TTF]<sub>2<\/sub>Cu[N(CN)<sub>2<\/sub>]Br<\/strong> (<em>Pnma<\/em>, T<sub>C0<\/sub><sup>meas<\/sup>\u00a0= <span style=\"color: #ff0000;\">11.4 K<\/span>)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2016\/03\/de-Sousa-BEDT_2015-sm.jpg\" rel=\"attachment wp-att-3434\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-full wp-image-3434\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2016\/03\/de-Sousa-BEDT_2015-sm.jpg\" alt=\"de Sousa-BEDT_2015-sm\" width=\"176\" height=\"303\" srcset=\"http:\/\/physikon.net\/wp-content\/uploads\/2016\/03\/de-Sousa-BEDT_2015-sm.jpg 176w, http:\/\/physikon.net\/wp-content\/uploads\/2016\/03\/de-Sousa-BEDT_2015-sm-174x300.jpg 174w, http:\/\/physikon.net\/wp-content\/uploads\/2016\/03\/de-Sousa-BEDT_2015-sm-87x150.jpg 87w\" sizes=\"auto, (max-width: 176px) 100vw, 176px\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">For \u03ba\u2013[BEDT\u2013TTF]<sub>2<\/sub>Cu[N(CN)<sub>2<\/sub>]Br , the hole conduction is in the ac-plane along the sulfur chains of the two BEDT-TTF molecules (each of which is bisected by a centrally located C\u2013C \u00a0bond).\u00a0 Equating the Cu<sup>+1<\/sup>[N(CN)<sub>2<\/sub>]<sup>\u20131<\/sup>Br<sup>\u20131<\/sup> anion layer with Cu<sup>+2<\/sup>[O<sup>\u20132<\/sup>][O<sup>\u20132<\/sup>] (type II layer) shows a factor of 1\/2 between the valences of the cuprate plane ions compared to those comprising the Cu[N(CN)<sub>2<\/sub>]Br anion molecule, leading to a base anion layer charge from rule (2c) of \u03c3<sub>0<\/sub>\/2, which must equal the positive charge available to the two BEDT-TTF (type I layer) molecules.\u00a0 Dividing this charge between the two BEDT-TTF molecules comprising the dimer [rule (1a)], and further distributing the charge among the two halves of the BEDT-TTF molecule [rule (1a)], yields an additional factor of (1\/2)(1\/2) such that \u03b3 = (1\/2)(1\/2)(1\/2) = 0.125. \u00a0Thus, one has\u00a0[1]:<\/p>\n<ul>\n<li>Type I reservoir: S-chains of the [BEDT-TTF]<sub>2<\/sub>\u00a0molecules<\/li>\n<li>Type II reservoir:\u00a0Cu[N(CN)<sub>2<\/sub>]Br<\/li>\n<li>\u03c3 = (1\/2) (1\/4) \u03c3<sub>0<\/sub> = 0.125 \u03c3<sub>0<\/sub><\/li>\n<li>\u03b7 = 1; \u03bd = 2<\/li>\n<li><em>A<\/em> = 54.4745 \u00c5<sup>2<\/sup>; \u03b6 = 2.4579 \u00c5<\/li>\n<li>T<sub>C0<\/sub><sup>calc<\/sup> = 11.61 K<\/li>\n<\/ul>\n<ol>\n<li>D. R. Harshman, A. T. Fiory and J. D. Dow, <a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/29\/295701\">J. Phys.: Condens. Matt.\u00a0<strong>23<\/strong>, 295701 (2011)<\/a>;\u00a0<a href=\"https:\/\/doi.org\/10.1088\/0953-8984\/23\/34\/349501\"><b>23<\/b>, 349501 (2011)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"Cs3C60\" name=\"Cs3C60\"><\/a><\/p>\n<hr \/>\n<p><strong>Cs<sub>3<\/sub>C<sub>60<\/sub><\/strong> (<em>Pm<span style=\"text-decoration: overline;\">3<\/span>n<\/em>, T<sub>C0<\/sub><sup>meas<\/sup>\u00a0= 38.3 K (A15, 0.93 GPa); Fm<em><span style=\"text-decoration: overline;\">3<\/span><\/em>m, 35.3 K (FCC, 0.73 GPa)) [1]\n<p style=\"text-align: justify;\">When viewed from a local perspective the surfaces of the C<sub>60<\/sub> molecules of the 3D (<em>A<\/em>,<em>B<\/em>)<sub>3<\/sub>C<sub>60<\/sub> macrostructure present an important adaptation of Coulombic pairing involving interactions between <em>interfacial<\/em> structures; the surface of the C<sub>60<\/sub> molecule and the three alkali-metal cations located on an intervening virtual surface. Given the n-type character of these materials, one associates the superconducting condensate with the C<sub>60<\/sub> molecules (type I reservoir), with the pairing mediated by holes on the cations (type II reservoir). \u00a0Both the A15 and FCC structures of Cs<sub>3<\/sub>C<sub>60<\/sub> are Mott insulators at ambient-pressure, exhibiting antiferromagnetism with a N\u00e9el temperature of ~46 K and ~2 K, respectively [<span style=\"color: #0000ff;\">Takabayashi2009<\/span>] <span style=\"color: #0000ff;\">[Ganin2008<\/span>] [<span style=\"color: #0000ff;\">Ganin2010<\/span>]. \u00a0Under hydrostatic pressure, both phases become superconducting; optimization of the A15 and FCC phases occur at 0.93 and 0.73 GPa, respectively, with corresponding measured T<sub>C0<\/sub> values of 38.36 K and 35.2 K [<span style=\"color: #0000ff;\">Takabayashi2009<\/span>] [<span style=\"color: #0000ff;\">Ganin2010<\/span>].<\/p>\n<p style=\"text-align: justify;\">The C<sub>60<\/sub> molecule has a diameter of 7.1 \u00c5 (radius <em>R<\/em> = 3.55 \u00c5) [<span style=\"color: #0000ff;\">Hedberg1991<\/span>], and comprises 12 regular pentagons, with a C\u2013C bond length of 1.45 \u00c5, and 20 hexagons, each with a weighted average C\u2013C bond length of (1.45 + 1.40)\/2 = 1.425 \u00c5 (the first term corresponding to the 6:5 bond and the second to the 6:6 (with equal weighting) [<span style=\"color: #0000ff;\">Pennington1996<\/span>]), such that the total surface area of the C<sub>60<\/sub> molecule at STP (assuming regular polygons) is <em>A<\/em> = 20(5.2757 \u00c5<sup>2<\/sup>) + 12(3.6173 \u00c5<sup>2<\/sup>) = 148.922 \u00c5<sup>2<\/sup>. \u00a0For simplicity, <em>A<\/em> is assumed the same for all materials (and pressures [<span style=\"color: #0000ff;\">Kaur_arXiv_2007<\/span>]) considered herein.\u00a0 Since \u03b7 = \u03c5 = 1 (where \u03c5 is the number of interacting type I layers\/interfaces per f.u.), the \u03b3 factor is given by rule (1b) as, \u03b3 = 1\/2, \u03c3 = (1\/2) [x \u2013 x<sub>0<\/sub>], and Eq. (1) reduced to,\u00a0T<sub>C0<\/sub>\u00a0= (72.28 K-\u00c5) [x] \u03b6<sup>\u20131<\/sup>,\u00a0with x = 3 for the stoichiometric (optimal) compounds [<span style=\"color: #0000ff;\">Haddon1993<\/span>]. \u00a0Note that all of this\u00a0assumes an insulating (or near-insulating) end material.<\/p>\n<p>For A15 Cs<sub>3<\/sub>C<sub>60<\/sub>, the three Cs cations are located at tetrahedral (T) sites facing the C<sub>60<\/sub> hexagons [<span style=\"color: #0000ff;\">Ganin2008;suppl.<\/span>] {check} (of average radius\u00a01.425 \u00c5) [<span style=\"color: #0000ff;\">Pennington1996<\/span>]. \u00a0In the fcc phase, on the other hand, the Cs cations are distributed between two interstitial locations; two Cs ions occupy the (T) sites, while the octahedral (O) site hosts the third [<span style=\"color: #0000ff;\">Ganin2010<\/span>].\u00a0 Notice that the Cs type II locations face unoccupied type I lattice positions along the radial, and can be related in 2D to defining \u03b6 in, <em>e<\/em>.<em>g<\/em>., the \u03b2-form doped metal-hydride-nitrides [<span style=\"color: #0000ff;\">Harshman2015<\/span>]. \u00a0Designating \u00a0to be the (weighted) radial interaction distance for each of the <em>N<\/em> nearest neighbor Cs sites, the average interaction distance is then an average of the occupied nearest-neighbor sites [<span style=\"color: #0000ff;\">Note<\/span>].<\/p>\n<p style=\"text-align: justify;\"><a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/A15.png\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2735 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/A15.png\" alt=\"A15\" width=\"158\" height=\"151\" srcset=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/A15.png 158w, http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/A15-157x150.png 157w, http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/A15-150x143.png 150w\" sizes=\"auto, (max-width: 158px) 100vw, 158px\" \/><\/a><strong><em>A15 (BCC packing) structure Cs<sub>3<\/sub>C<sub>60<\/sub><\/em><\/strong> \u2013 Measurements conducted on a 77.7(6)% A15 enriched sample with stoichiometry Cs<sub>2.85(1)<\/sub>C<sub>60<\/sub> (space group Pmn) and <em>T<\/em><sub>C<\/sub> = 38.3 K (optimized at 0.93 GPa) show V<sub>0.93<\/sub>(T<sub>C<\/sub>) = 1533.6 \u00c5<sup>3<\/sup> and <em>a<\/em><sub>0.93<\/sub>(T<sub>C<\/sub>) = 11.5320 \u00c5 [<span style=\"color: #0000ff;\">Takabayashi2009<\/span>]. \u00a0Determining \u03b6 in the A15 compound is straight forward since Rietveld refinement of this structural phase indicates that the Cs cations occupy only the hexagon-coordinated \u00a06<em>d<\/em> tetrahedral (T) sites; the 6<em>c<\/em> sites are left empty.\u00a0 Given that the (T) position is located a distance 5<sup>1\/2<\/sup><em>a<\/em><sub>0<\/sub>\/4 from the center of a C<sub>60<\/sub> molecule, and faces the center of the hexagon of radius Rthe average interaction distance \u03b6 = \u03b6<sub>(T)<\/sub> = 5<sup>1\/2<\/sup><em>a<\/em><sub>0.93<\/sub>\/4 \u2013 (<em>R<\/em><sup>2<\/sup> \u2013 1.425<sup>2<\/sup>)<sup>1\/2<\/sup> =\u00a0 6.4463 \u2013 3.2514 = 3.1952 \u00c5.\u00a0 From this, the above equation gives T<sub>C0<\/sub><sup>calc.<\/sup> = 38.19 K in excellent agreement with experiment. \u00a0As no octahedral sites are occupied, the average over nearest-neighbor Cs cations is trivial.<\/p>\n<p style=\"text-align: justify;\"><a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/FCC.png\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2733 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/FCC.png\" alt=\"FCC\" width=\"158\" height=\"153\" srcset=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/FCC.png 158w, http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/FCC-155x150.png 155w, http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/FCC-150x145.png 150w\" sizes=\"auto, (max-width: 158px) 100vw, 158px\" \/><\/a><strong><em>The FCC packing structure Cs<sub>3<\/sub>C<sub>60<\/sub><\/em><\/strong> \u2013 At <em>T<\/em><sub>C<\/sub> = 35.3 K and applied pressure of 0.73 GPa, the volume per unit cell for an 85.88(2)% fcc (Fmm space group) sample with stoichiometry Cs<sub>2.901(6)<\/sub>C<sub>60<\/sub> is measured to be V<sub>0.73<\/sub>(<em>T<\/em><sub>C<\/sub>) = 3038.4 \u00c5<sup>3<\/sup>, corresponding to a lattice parameter of <em>a<\/em><sub>0.73<\/sub>(<em>T<\/em><sub>C<\/sub>) = 14.4838 \u00c5 [<span style=\"color: #0000ff;\">Ganin2010<\/span>].\u00a0 Unlike its A15 counterpart, the C<sub>60<\/sub> molecules of the fcc phase exhibit merohedral disorder [<span style=\"color: #0000ff;\">Pennington1996<\/span>] [<span style=\"color: #0000ff;\">Potocnik2014<\/span>].\u00a0 The type II surface comprises 8 Cs cations occupying the (T) sites (with four neighboring C<sub>60<\/sub> molecules) and 6 in the octahedral (O) sites, also with six C<sub>60<\/sub> neighbors; the number of Cs cations per C<sub>60<\/sub> is then 8\/4 + 6\/6 = 3 [<span style=\"color: #0000ff;\">Note<\/span>]. \u00a0From Ref. [<span style=\"color: #0000ff;\">Potocnik2014<\/span>], the (T) sites are located over the center of the C-hexagons a distance 3<sup>1\/2<\/sup><em>a<\/em><sub>0<\/sub>\/4 from the C<sub>60<\/sub> center, while the (O) sites lie above the midpoint of the 6:6 hexagon C-C bonds, a distance <em>a<\/em><sub>0<\/sub>\/2 from the C<sub>60<\/sub> center.\u00a0 Consequently, \u03b6<sub>(T)<\/sub> = 3<sup>1\/2<\/sup><em>a<\/em><sub>0.73<\/sub>\/4 \u2013 (<em>R<\/em><sup>2<\/sup> \u2013 1.425<sup>2<\/sup>)<sup>1\/2<\/sup> = 3.0203 \u00c5, and \u03b6<sub>(O)<\/sub> = <em>a<\/em><sub>0.73<\/sub>\/2 \u2013 (<em>R<\/em><sup>2<\/sup> \u2013 0.7<sup>2<\/sup>)<sup>1\/2<\/sup> = 3.7616 \u00c5.\u00a0 Taking the weighted average\u00a0then gives, \u03b6 = [(8\/14)\u03b6<sub>(T)<\/sub> + (6\/14)\u03b6<sub>(O)<\/sub>] = 3.3380 \u00c5, which from Eq. (3) gives, <em>T<\/em><sub>C0<\/sub><sup>calc.<\/sup> = 36.88 K.\u00a0 While the agreement with experiment is reasonable, the difference is sufficiently large to suggest that pair breaking due to the merohedral disordering of the C<sub>60<\/sub> molecules may be a factor.<\/p>\n<p style=\"text-align: justify;\"><strong>Note:<\/strong>\u00a0There&#8217;s a difference between the number of cation sites per unit cell (12 for fcc) and the number of cation sites that are the nearest neighbors to a given C<sub>60<\/sub> (14 for fcc); one is interested in the latter, not the former when calculating \u03b6. Consider the C<sub>60<\/sub> situated at coordinates (0,0,0) and its nearest neighboring Cs; the 8 tetrahedrally coordinated Cs sites (T) are located at (<em>i<\/em>,<em>j<\/em>,<em>k<\/em>)(<em>a<\/em><sub>0<\/sub>\/4) and the 6 octahedrally coordinated Cs sites (O) are located at (<em>i<\/em>,0,0)(<em>a<\/em><sub>0<\/sub>\/2), (0,<em>j<\/em>,0)(<em>a<\/em><sub>0<\/sub>\/2), and (0,0,<em>k<\/em>)(<em>a<\/em><sub>0<\/sub>\/2) (with <em>i<\/em>,<em>j<\/em>,<em>k<\/em> = +1 or \u20131).\u00a0 This C<sub>60<\/sub> is neighbored by 8 (T) Cs, shared by four C<sub>60<\/sub>s, so the number of (T) Cs per this C<sub>60<\/sub> = 8\/4 = 2.\u00a0 And by 6 (O) Cs, shared by six C<sub>60<\/sub> molecular anions, so the number of (O) Cs per this C<sub>60<\/sub> is 6\/6 = 1.\u00a0 Thus the total number of Cs per C<sub>60<\/sub> comes out correctly as 3.\u00a0 The model for \u03b6 is based on the type II shell of Cs surrounding a given C<sub>60<\/sub>.\u00a0 The fractions of (T) and (O) Cs sites per C<sub>60<\/sub> are inequivalent to the fractions of nearest-neighbor (T) and (O) sites, because of the model geometry and coordination sharing. In summary one has [1]:<\/p>\n<ul>\n<li>Type I reservoir: C<sub>60<\/sub><\/li>\n<li>Type II reservoir: A<sub>3<\/sub><\/li>\n<li>\u03b7 = 1; \u03bd = 1<\/li>\n<li>\u03c3 = \u03b3 [3 \u2013x<sub>0<\/sub>] = (1\/2) [3 ] = 1.5 (assuming x<sub>0<\/sub>\u00a0= 0)<\/li>\n<li><strong>[BCC]:<\/strong><em> A<\/em> = 148.922 \u00c5<sup>2<\/sup>; \u03b6 = 3.1949 \u00c5 (assuming negligible pressure dependence in <em>A<\/em>);\u00a0T<sub>C0<\/sub><sup>mea<\/sup><sup>s<\/sup>\u00a0= 38.36 K; T<sub>C0<\/sub><sup>calc<\/sup> = 38.19 K (i.e., A15 phase)<\/li>\n<li><strong>[FCC]:<\/strong><em> A<\/em> = 148.922 \u00c5<sup>2<\/sup>; \u03b6 = 3.383 \u00c5\u00a0(assuming negligible pressure dependence in <em>A<\/em>);\u00a0T<sub>C0<\/sub><sup>mea<\/sup><sup>s<\/sup>\u00a0= 35.2 K; T\u00a0<sub>C0<\/sub><sup>calc<\/sup> = 36.88 K<\/li>\n<\/ul>\n<ol>\n<li>D. R. Harshman and A. T. Fiory,\u00a0<a href=\"https:\/\/doi.org\/10.1088\/1361-648X\/aa5dbd\">J. Phys.: Condens. Matter <strong>29<\/strong>, 145602 (2017)<\/a>.<\/li>\n<\/ol>\n<ul>\n<li>Y. Takabayashi <em>et al.<\/em>,\u00a0Science <strong>323<\/strong>, 1585 (2009).<\/li>\n<li>A. Y. Ganin <em>et al.<\/em>,\u00a0Nature Mater. <strong>7<\/strong>, 367; suppl. (2008).<\/li>\n<li>A. Y. Ganin <em>et al.<\/em>,<em>\u00a0<\/em>Nature <strong>466<\/strong>, 221; suppl. (2010).<\/li>\n<li>C. H. Pennington and V. A. Stenger, Rev. Mod. Phys. <strong>68<\/strong>, 855 (1996).<\/li>\n<li>R. C. Haddon, Pure and Appl. Chem.\u00a0<strong>65<\/strong>, 11 (1993).<\/li>\n<li>A. Potocnik <em>et al<\/em>., Chem. Sci. <strong>5<\/strong>, 3008 (2014).<\/li>\n<li>K. Hedberg <em>et al<\/em>., Science <strong>254<\/strong>, 410 (1991).<\/li>\n<li>N. Kaur <em>et al<\/em>., arXiv (2007).<\/li>\n<\/ul>\n<hr \/>\n<p><a href=\"H3S\" name=\"H3S\"><\/a><\/p>\n<hr \/>\n<p><strong>H<sub>3<\/sub>S<\/strong> (<em>Im<span style=\"text-decoration: overline;\">3<\/span>m<\/em>, T<sub>C0<\/sub><sup>meas<\/sup>\u00a0= 200.0 K (155 GPa)) [1]<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/H3S_JPCM_Fig3.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-medium wp-image-3910\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/H3S_JPCM_Fig3-300x290.jpg\" alt=\"\" width=\"300\" height=\"290\" srcset=\"http:\/\/physikon.net\/wp-content\/uploads\/H3S_JPCM_Fig3-300x290.jpg 300w, http:\/\/physikon.net\/wp-content\/uploads\/H3S_JPCM_Fig3-155x150.jpg 155w, http:\/\/physikon.net\/wp-content\/uploads\/H3S_JPCM_Fig3-150x145.jpg 150w, http:\/\/physikon.net\/wp-content\/uploads\/H3S_JPCM_Fig3.jpg 364w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">The H3S system represents the first true 3D material for which the interfacial Coulombic interaction model has been applied. \u00a0It is also the first material in which the type I and type II charge reservoirs contain the same ionic species.<\/p>\n<ul>\n<li>Type I reservoir: half-sublattice<\/li>\n<li>Type II reservoir: half-sublattice<\/li>\n<li>\u03b7 = 1; \u03bd = 1<\/li>\n<li>\u03c3 = \u03b3 [x] = (1\/2) [3.43 + 3.43] = 3.43<\/li>\n<li><em>A<\/em> = 3<em>a<\/em><sub>0<\/sub><sup>2<\/sup> = 28.5017 \u00c5<sup>2<\/sup> (<em>a<\/em><sub>0<\/sub> = 3.0823 \u00c5); \u03b6 = <em>a<\/em><sub>0<\/sub>\/2<sup>1\/2<\/sup> = 2.1795 \u00c5;\u00a0T<sub>C0<\/sub><sup>mea<\/sup><sup>s<\/sup>\u00a0= 200 K (155 GPa); T<sub>C0<\/sub><sup>calc<\/sup> = 198.5 \u00b1 3.0 K<\/li>\n<\/ul>\n<ol>\n<li>D. R. Harshman and A. T. Fiory,\u00a0<a href=\"https:\/\/doi.org\/10.1088\/1361-648X\/aa80d0\">J. Phys.: Condens. Matter <strong>29<\/strong>, 445702 (2017)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"TBG\" name=\"TBG\"><\/a><\/p>\n<hr \/>\n<p><strong>Twisted Bilayer Graphene (gated)<\/strong> (T<sub>C0<\/sub><sup>meas<\/sup>\u00a0= 1.83(5) K at 0 GPa; 2.86(5) K at 1.33 GPa) [1]<img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-5407 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/gTBG_schematic-1-300x151.png\" alt=\"\" width=\"300\" height=\"151\" srcset=\"http:\/\/physikon.net\/wp-content\/uploads\/gTBG_schematic-1-300x151.png 300w, http:\/\/physikon.net\/wp-content\/uploads\/gTBG_schematic-1-150x75.png 150w, http:\/\/physikon.net\/wp-content\/uploads\/gTBG_schematic-1-250x126.png 250w, http:\/\/physikon.net\/wp-content\/uploads\/gTBG_schematic-1.png 729w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/p>\n<p style=\"text-align: justify;\">The TBG system is an extended 2D lattice where, like the 3D compound H<sub>3<\/sub>S, the two reservoirs are essentially identical, containing both superconducting and mediating charges.<\/p>\n<ul>\n<li>Type I reservoir: first graphene sheet<\/li>\n<li>Type II reservoir: second graphene sheet<\/li>\n<li>\u03b7 = 1; \u03bd = 1<\/li>\n<li>\u03b8 = 1.05\u00b0 (0 GPa); 1.27\u00b0 (1.33 GPa)<\/li>\n<li>\u03c3\/<em>A<\/em> = \u03b3 |<em>n<\/em><sub>opt<\/sub> &#8211; <em>n<\/em><sub>0<\/sub>| = 1\/2|<em>n<\/em><sub>opt<\/sub> &#8211; <em>n<\/em><sub>0<\/sub>|<\/li>\n<li>\u03b6 = <em>a<\/em><sub>0<\/sub>\/2<sup>1\/2<\/sup> = 3.5 \u00c5;\u00a0T<sub>C0<\/sub><sup>mea<\/sup><sup>s<\/sup>\u00a0= 1.83(5) K; T<sub>C0<\/sub><sup>calc<\/sup> = 1.94(4) K at 0 GPa<\/li>\n<li>\u03b6 = <em>a<\/em><sub>0<\/sub>\/2<sup>1\/2<\/sup> = 3.42 \u00c5;\u00a0T<sub>C0<\/sub><sup>mea<\/sup><sup>s<\/sup>\u00a0= 2.86(5) K; T<sub>C0<\/sub><sup>calc<\/sup> = 3.02(3) K at 1.33 GPa<\/li>\n<\/ul>\n<ol>\n<li>D. R. Harshman and A. T. Fiory, <a href=\"https:\/\/doi.org\/10.1007\/s10948-019-05183-9\">J. Supercond. Nov. Magn.\u00a0<strong>33<\/strong>, 367 (2020)<\/a>.<\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"LaH10\" name=\"LaH10\"><\/a><\/p>\n<hr \/>\n<p><strong>Compressed LaH<sub>10<\/sub><\/strong> (T<sub>C0<\/sub><sup>meas<\/sup>\u00a0= 251(1) K at 169(4) GPa; 262(1) at 192(4) GPa) [1]<img loading=\"lazy\" decoding=\"async\" class=\"alignright size-thumbnail wp-image-5610\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/Fig1-150x150.png\" alt=\"\" width=\"150\" height=\"150\" \/><\/p>\n<p style=\"text-align: justify;\">The metal-hydrogen clathrate system is another 3D example where the mediating (type II) charges occupy the central metal ions and the superconducting (type I) charges occupy the surrounding hydrogen cage.<\/p>\n<ul>\n<li>Type I reservoir: H-cage<\/li>\n<li>Type II reservoir: La<\/li>\n<li>\u03b7 = 1; \u03bd = 1<\/li>\n<li>\u03b3 = 1\/2<\/li>\n<li>\u03c3 =\u00a0\u03b3 (10 + 3) = 0.5 (13) = 6.5<\/li>\n<li>169(4) GPa: <em>A<\/em> = 50.29(27) \u00c5<sup>2<\/sup>; \u03b6 = 1.795(5)\u00c5; T<sub>C0<\/sub> = 249.8(1.3) K<\/li>\n<li>192(4) GPa: <em>A<\/em> = 48.18(36) \u00c5<sup>2<\/sup>; \u03b6 =1.757(7) \u00c5; T<sub>C0<\/sub> = 260.7(2.0) K<\/li>\n<\/ul>\n<ol>\n<li>D. R. Harshman and A. T. Fiory, <a href=\"https:\/\/doi.org\/10.1007\/s10948-020-05557-4\">J. Supercond. Nov. Magn.\u00a0<strong>33<\/strong>, 2945 (2020).<\/a><\/li>\n<\/ol>\n<hr \/>\n<p><a href=\"CSH7\" name=\"CSH7\"><\/a><\/p>\n<hr \/>\n<p><strong>Compressed CSH<sub>7<\/sub><\/strong> (maximum T<sub>C0<\/sub><sup>meas<\/sup>\u00a0= 287.7\u00b11.2 K at 267 GPa [1]<img loading=\"lazy\" decoding=\"async\" class=\"alignright size-thumbnail wp-image-5610\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/Figure1_JAP21-AR-POH2022-04111-_300x250.jpg\" alt=\"\" width=\"300\" height=\"250\" \/><\/p>\n<p style=\"text-align: justify;\">For the 3D C-S-H system, mediating (type II) charges occupy the CH<sub>4<\/sub> intercalates, and the superconducting (type I) charges occupy the surrounding H<sub>3<\/sub>S-like sub-lattice.<\/p>\n<ul>\n<li>Type I reservoir: H<\/li>\n<li>Type II reservoir: La<\/li>\n<li>\u03b7 = 1; \u03bd = 1<\/li>\n<li>\u03b3 = 1\/2<\/li>\n<li>\u03c3 =\u00a0\u03b3 (7 + 4 + 4) = 0.5 (115) = 7.5<\/li>\n<li>267 GPa: <em>A<\/em> = 48.11(14) \u00c5<sup>2<\/sup>; \u03b6 = 1.737(4)\u00c5; T<sub>C0<\/sub> = 283.6\u00b13.5 K<\/li>\n<\/ul>\n<ol>\n<li>Dale R. Harshman and Anthony T. Fiory, <a href=\"https:\/\/doi.org\/10.1063\/5.0065317\">Journal of Applied Physics <strong>131<\/strong>, 015105 (2021)<\/a>; see also <a href=\"https:\/\/doi.org\/10.48550\/arXiv.2201.01860\">arXiv_v3 (2023<\/a>).<\/li>\n<\/ol>\n<hr \/>\n","protected":false},"excerpt":{"rendered":"<p><a href=\"#y123_90\" name=\"Y123_90\"><\/a><\/p>\n<p><strong>YBa2Cu3O6.92<\/strong> (<em>Pmmm<\/em>, TC0meas = 93.78 K)<a href=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/REBa2Cu3O7-d.gif\"><img loading=\"lazy\" decoding=\"async\" class=\" size-full wp-image-2173 alignright\" src=\"http:\/\/physikon.net\/wp-content\/uploads\/2015\/07\/REBa2Cu3O7-d.gif\" alt=\"REBa2Cu3O7-d\" width=\"176\" height=\"290\" \/><\/a><\/p>\n<p style=\"text-align: justify;\">To determine \u03c30, one considers oxygen content <em>x<\/em> above the minimum value (<em>x<\/em>0 = 6.35 [1]) required for superconductivity to occur. \u00a0The total oxygen content associated with  \u2026 <a href=\"http:\/\/physikon.net\/?page_id=2359\"> Continue reading <span class=\"meta-nav\">&rarr; <\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":3292,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-2359","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/pages\/2359","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/physikon.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2359"}],"version-history":[{"count":497,"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/pages\/2359\/revisions"}],"predecessor-version":[{"id":8177,"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/pages\/2359\/revisions\/8177"}],"up":[{"embeddable":true,"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/pages\/3292"}],"wp:attachment":[{"href":"http:\/\/physikon.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2359"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}