Superconductivity at 80 K in (Sr,Ca)3Cu2O4+δCl2-y induced by apical oxygen doping

Abstract

planet in our Solar System is Jupiter and why there are none more massive is not understood. The lifetime of our gaseous proto-planetary disk may have been short 28 or the disk may have been tidally truncated by the growing planet itself 29 • Good statistics on the population of EGPs will better constrain protoplanetary disk processes. The absence of a Jupiter-class planet in a planetary system would imply a very different population of cometary-sized planetesimals than exists in our own Solar System, and this may have important implications for the origin, evolution and survival of life on rocky 'terrestrial' planets 30 .Only sensitive and systematic searches, such as those we anticipate over the next decade, will directly address these important issues of planet formation. D RECENT work 1 ' 2 has shown that superconducting copper oxyhalides can be synthesized, with the La 2 Cu0 4 structure but with no oxygen in the 'apical' positions outside the Cu0 2 planes. For these materials to be rendered superconducting, charge carriers must be introduced into the Cu0 2 planes; in previous work, positive carriers (holes) have been introduced by the incorporation of interstitial fluorine in Sr 2 Cu0 2 F z+O (transition temperature Tc = 46 K) 1 , or by the substitution of sodium for calcium in (Ca,Na)zCuOzCiz (Tc = 26 K) 2 . Here we present an alternative doping approach for this copper oxyhalide family: holes are introduced by partially replacing the (monovalent) halogen that occupies the apical sites with (divalent) oxygen. We have obtained bulk superconductivity with Tc above 77 K in a new double-layer compound (Sr,Ca) 3 Cuz0 4 +0Ciz-y, which is isostructural with (La,Sr)z-CaCu206 (ref.3), with (Sr,Ca) at the (La,Sr) orCa sites, and Cl at the apical sites outside the Cu02 planes.We synthesized Sr 3 -xCaxCu 2 0 4 +5Cl 2 -y compounds using a high-pressure, high-temperature technique, which has proven effective in searching for new homologous series of high-Tc superconducting copper oxides 4 -6 . The precursors Sr 2 Cu0 3 , SrCu0 2 and Ca 2 Cu0 3 were prepared by solid-state reaction between CuO and SrC0 3 or CaC0 3 (each 99.9% pure). Precursor Sr 2 Cu0 2 CI 2 (CI source of the sample) was obtained by the reaction between CuO and fully dehydrated SrCI 2 (99% pure)

Structural and electrical properties of infinite-layer CaCuO2 under high pressure

“…Some novel superconductors that could not be synthesized at ambient pressure can be obtained under high pressure [1][2][3][4][5][6][7][8][9]. High pressure has an overall effect on the structure and physical properties of high-T c superconductor (HTS) [10][11][12][13][14][15].…”

The unusual morphology, structure, and magnetic property evolution of glassy carbon upon high pressure treatment

“…It thus offers the opportunity to study the topology related effect on graphite related material. High pressure plays a unique role in designing, modifying, tailoring the structure, morphology and consequently the physical properties of matter, such as those established in the research on high T C superconductors [8] . These can be further verified by a series of more recently discovered superconductivity upon the application of high pressure in such unusual elements like oxygen, lithium, boron, etc.…”

Synthesis, Structure, and Characterization of a Layered Mixed Metal Oxychloride, PbVO3Cl

“…[1][2][3][4][5][6][7][8] Thus, designing new layered compounds still remains a continuing challenge. Among them, layered materials consisting of asymmetric units are of particular interest attributable to their potential applications to the frequency doubling and waveguiding materials, piezoelectric sensors, and memory materials.…”