{"id":5669,"date":"2020-06-18T16:08:20","date_gmt":"2020-06-18T23:08:20","guid":{"rendered":"http:\/\/physikon.net\/?p=5669"},"modified":"2023-05-26T10:58:58","modified_gmt":"2023-05-26T17:58:58","slug":"high-tc-superconductivity-in-hydrogen-clathrates-mediated-by-coulomb-interactions-between-hydrogen-and-central-atom-electrons","status":"publish","type":"post","link":"http:\/\/physikon.net\/?p=5669","title":{"rendered":"High-Tc<\/sub> Superconductivity in Hydrogen Clathrates Mediated by Coulomb Interactions between Hydrogen and Central-Atom Electrons"},"content":{"rendered":"

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Hign TC<\/sub> Superconductivity in Hydrogen Clathrates Mediated by Coulomb Interactions between Hydrogen and Central-Atom Electrons<\/strong>, D. R. Harshman and A. T. Fiory [arXiv<\/a>]\n

The uniquely characteristic macrostructures of binary hydrogen-clathrate compounds MHn<\/sub> formed at high pressure, a cage of hydrogens surrounding a central-atom host, is theoretically predicted in various studies to include structurally stable phonon-mediated superconductors. High superconductive transition temperatures T<\/em>C<\/sub> have thus far been measured for syntheses with M<\/em> = La, Y, and Th. In compressed LaH10<\/sub>, independent studies report T<\/em>C<\/sub> of 250 K and over 260 K, a maximum in T<\/em>C<\/sub> with pressure P<\/em>, and normal-state resistance scaling with temperature (suggesting unconventional pairing). According to reported band structure calculations of Fm<\/em>3<\/span>m<\/em>-phase LaH10<\/sub>, the La is anionic, with the chemical valence electrons appearing evenly split between La and H10<\/sub>. Thus, compressed LaH10<\/sub> contains the combination of structure, charge separation, and optimal balanced allocation of valence electrons for supporting unconventional high-T<\/em>C<\/sub> superconductivity mediated by Coulomb interactions between electronic charges associated with La and H10<\/sub>. A general expression for the optimal superconducting transition temperature for M<\/em>Hn<\/sub> clathrates is derived as T<\/em>C0<\/sub> = k<\/em>B<\/sub>-1<\/sup>\u039b[(n + v<\/em>)\/2A<\/em>]1\/2<\/sup>e<\/em>2<\/sup>\/\u03b6, where \u039b is a universal constant, (n + v<\/em>) is the chemical valence sum per formula unit, taking unity for H and v<\/em> for atom M<\/em>, A<\/em> is the surface area of the H-polyhedron cage, and \u03b6 is the mean distance between the M<\/em> site and the centroids of the polyhedron faces. Applied to Fm<\/em>3<\/span>m<\/em> LaH10<\/sub>, T<\/em>C0<\/sub> values of 249.8(1.3) K and 260.7(2.0) K are found for the two experiments. Associated attributes of charge allocation, structure, effective Coulomb potential, and H-D isotope effect in T<\/em>C<\/sub> of Fm<\/em>3<\/span>m<\/em> LaH10<\/sub> and Im<\/em>3<\/span>m<\/em> H3<\/sub>S are discussed, along with a generalized prospective for Coulomb-mediated superconductivity in M<\/em>Hn<\/sub>.<\/p>\n\n

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Measured transition temperatures TC<\/sub> for LaH10<\/sub> and H3<\/sub>S are plotted against (\u2113\u03b6)\u22121<\/sup>. The solid line represents the interlayer Coulomb pairing theory for Tc0. Results for the mixed-phase, non-optimal samples of YH9<\/sub>, YH6<\/sub>, ThH10<\/sub>, and ThH9<\/sub> are also presented for comparison; the red dashed trend line is a fit to these data as described in the text. Horizontal error bars correspond to the lower and upper pressure limits.<\/p>\n\n<\/figcaption><\/figure>\n<\/div>\n\n\n

Dale R. Harshman and Anthony T. Fiory, Journal of Superconductivity and Novel Magnetism 33<\/strong>, 2945 (2020)<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[53,9,8,28],"tags":[],"class_list":["post-5669","post","type-post","status-publish","format-standard","hentry","category-clathrates","category-high-tc-superconductivity","category-high-tc-theory","category-transition-temperature"],"_links":{"self":[{"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/posts\/5669","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"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=5669"}],"version-history":[{"count":43,"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/posts\/5669\/revisions"}],"predecessor-version":[{"id":8115,"href":"http:\/\/physikon.net\/index.php?rest_route=\/wp\/v2\/posts\/5669\/revisions\/8115"}],"wp:attachment":[{"href":"http:\/\/physikon.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5669"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/physikon.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5669"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/physikon.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5669"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}