Superconductivity with Tc(zero) above 105 K in Tl-containing septenary oxides with Y1Ba2Cu3Oy-like structure
01 Feb 1990-Physica C-superconductivity and Its Applications (North-Holland)-Vol. 165, Iss: 3, pp 347-353
TL;DR: In this paper, a family of high-T c superconductors with T c(zero) above 105 K was described, which represent one of the first cases where chemical substitution has significantly raised T c in a known compound.
Abstract: A family of high- T c superconductors with T c(zero) above 105 K is described. The compounds are seven-element blends with the general formula Tl 0.5 Pb 0.5 Ca 0.8 A 0.2 Sr 2 Cu 2 O x ( A = Y ), and rare-earth elements La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb). The results represent one of the first cases where chemical substitution has significantly raised T c in a known compound. The septenary compounds are tetragonal in structure with almost identical lattice parameters to those of now-famous Y 1 Ba 2 Cu 3 O y structure. The samples were highly reproducible, stable and remarkably homogeneous both in composition and structure. The preparative conditions were found to be much less stringent than those of other copper-based high- T c superconductors.
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TL;DR: The septenary compound (Tl 0.5Pb0.5) (Ca1−yYy)Sr2Cu2O7−δ system as Ca2+ is replaced by Y3+. Superconductivity is observed over the homogeneity range y = 0.6-1.0, the material undergoes a metal-semiconductor transition as discussed by the authors.
75 citations
TL;DR: In this article, a series of superconducting cuprates with nominal compositions (Pb0.5Cd 0.5)Sr2(Y1-xCax)Cu2O7- delta is reported.
Abstract: A novel series of superconducting cuprates with the nominal compositions (Pb0.5Cd0.5)Sr2(Y1-xCax)Cu2O7- delta is reported. These readily form as the (Pb, Cd)-1212 phase in air and they exhibit superconductivity without the need for annealing or quenching treatments. The highest transition temperature recorded in these materials is 92 K as measured by the onset of diamagnetism.
58 citations
TL;DR: In this article, the authors systematically investigated the influence of both pressure and intrisic effects on Tc in high-temperature superconductors and found that Tc is influenced not only by a pressure-induced increase in charge carrier density, but also by intisic effects in Tl0.5Pb 0.5Sr2Ca 1−xYxCu2O7.
Abstract: The pressure dependence of Tc in high-temperature superconductors is experimentally found to be influenced not only by a pressure-induced increase in charge carrier density but also by intrisic effects. The influence of both contributions was systematically investigated in Tl0.5Pb0.5Sr2Ca1−xYxCu2O7. The behavior of superconductors with three or four CuO2-layers is further complicated by the inequivalence of the inner and outer CuO2-layers. High-pressure experiments up to 46 GPa are analyzed in view of the above.
44 citations
TL;DR: In this article, the partial substitution of vanadium for thallium in the crystal lattice stabilizes the TlSr2CaCuCu2Oy phase and enhances superconductivity up to 80K.
28 citations
TL;DR: In this article, the authors reported the growth of thin films of (Tl,Pb)Sr2Ca1−xYxCu2O7 with x=0.2 by off-axis magnetron sputtering in the presence of thallium oxide vapor.
Abstract: We report the growth of thin films of (Tl,Pb)Sr2Ca1−xYxCu2O7 with x=0–0.2 by off‐axis magnetron sputtering in the presence of thallium oxide vapor. The (Tl,Pb)Sr2Ca1−xYxCu2O7 films are highly c‐axis oriented on the pseudocubic (100) surface of LaAlO3 or on (001)NdGaO3. The 〈100〉 axes of the films grown on LaAlO3 align to the pseudocubic 〈100〉 axes of the substrate while for films on NdGaO3 they are rotated 45° relative to orthorhombic 〈100〉 substrate axes. After an in situ heat treatment, undoped (Tl,Pb)Sr2CaCu2O7 films are superconducting at temperatures up to 82 K, compared with 85 K for the bulk material. Yttrium doping on the calcium site increased the transition temperature as expected. The highest transition temperature observed was 86 K for x=0.1 and 93 K for x=0.2.
26 citations
References
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TL;DR: A stable and reproducible superconductivity transition between 80 and 93 K has been unambiguously observed both resistively and magnetically in a new Y-Ba-Cu-O compound system at ambient pressure.
Abstract: A stable and reproducible superconductivity transition between 80 and 93 K has been unambiguously observed both resistively and magnetically in a new Y-Ba-Cu-O compound system at ambient pressure. An estimated upper critical field H c2(0) between 80 and 180 T was obtained.
5,965 citations
TL;DR: In this paper, a new high-Tc oxide superconductor of the BiSrCa-Cu-O system without any rare earth element was discovered, which has Tc of about 105 K, higher than that of YBa2Cu3O7 by more than 10 K.
Abstract: We have discovered a new high-Tc oxide superconductor of the Bi-Sr-Ca-Cu-O system without any rare earth element. The oxide BiSrCaCu2Ox has Tc of about 105 K, higher than that of YBa2Cu3O7 by more than 10 K. In this oxide, the coexistence of Sr and Ca is necessary to obtain high Tc.
2,698 citations
TL;DR: Observation de la transition supraconductrice a 91 K, sur 1,5 K and determination of the densite de courant critique, de l'effet Meissner, du champ critique, du parametre de Sommerfeld, de parametres GL.
Abstract: We have prepared and identified as a single phase the high-temperature superconducting compound in the chemical system Y-Ba-Cu-O, an orthorhombic, distorted oxygen-deficient perovskite of stoichiometry ${\mathrm{Ba}}_{2}$${\mathrm{YCu}}_{3}$${\mathrm{O}}_{9\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ (\ensuremath{\delta}\ensuremath{\simeq}2.1). Samples exhibit zero resistance at 91 K, with a transition width of 1.5 K. The Meissner effect attains a value of 76% of the independently measured diamagnetic susceptibility. We estimate parameters that characterize this superconductor, e.g., \ensuremath{\gamma}\ensuremath{\simeq}3--5 mJ (mole Cu${)}^{\mathrm{\ensuremath{-}}1}$ ${\mathrm{K}}^{\mathrm{\ensuremath{-}}2}$. The critical current density at 77 K and H=0 exceeds 1100 A/${\mathrm{cm}}^{2}$.
1,264 citations
TL;DR: The results suggest that the unique square planar Cu atoms, each surrounded by four or six oxygen atoms, are crucial to the superconductivity of oxides in general.
Abstract: Superconductivity has been found in the 90-K range in ABa2Cu3O(6 + x) with A = La, Nd, Sm, Eu, Gd, Ho, Er, and Lu in addition to Y. The results suggest that the unique square-planar Cu atoms, each surrounded by four or six oxygen atoms, are crucial to the superconductivity of oxides in general. In particular, the high Tc of ABa2Cu3O(6 + x) is attributed mainly to the quasi-two-dimensional assembly of the CuO2-Ba-CuO(2 + x)Ba-CuO2 layers sandwiched between two A layers, with particular emphasis in the CuO(2 + x) layers. Higher-Tc oxides are predicted for compounds with bigger assemblies of CuO2 layers coupled by Ba layers.
719 citations
TL;DR: In this paper, the authors reported superconductivity in the rare earth-free TI-Ba-Cu-O system with a resistance starting at 90 K with zero resistance at 81 K.
Abstract: The initial discovery by Bednorz and Muller1 of 35-K superconductivity in the La-Ba-Cu-O system has stimulated worldwide activity in searching for higher-temperature superconductors. Elemental substitution has proved to be most effective in raising transition temperature. Substitution of Sr for Ba has produced 40-K superconductivity2–5and substitution of Y for La has produced a new high-temperature superconductor with transition temperature above liquid-nitrogen temperature6. A class of superconducting compounds of the form RBa2Cu307-x has been explored by further substitutions of other rare earths (Y is considered in the rare-earth [RI category here) for Y7-13. To date, a rare earth, an alkaline earth, copper and oxygen have been required for all high-temperature superconductors14,15. (Zhanget al 14reported 90-K superconductivity in the Th-Ba-Pb(Zr)-Cu-O system. Panetal15reported 50-K superconductivity in the Y-Ba-Ag-O system. As Th is a member of the actinide series which belongs to the same Group 3B in the periodic table as the lanthanide series and Ag belongs to the same Group 1B as Cu, high-temperature supercon-ductors are still thought to be closed in the Group 3B—Group 2A-Group 1B—oxygen system. ) Only partial substitutions ha. e led to superconductors, but with no significant rise of transition tem-perature (the only exception is 40-K superconductivity in La2CuO4-x , refs 16, 17). Here we report superconductivity in the rare-earth-free TI-Ba-Cu-O system. We have obsened sharp drops of resistance starting above 90 K with zero resistance at 81 K in this system. Magnetic measurements have confirmed that these sharp drops of resistance in the TI-Ba-Cu-O samples origi-nate from superconductivity. The samples are stable in air for at least two months, and their preparation is easily reproduced.
645 citations