Superconductivity studies on the MTlSrCaCuO (M = Rate Earth, Sc, Y, Pb, Bi, Th) system☆
TL;DR: In this paper, the authors show that superconductivity in the range 40-77K can be achieved in this system depending on the M-ion, and the minimum amount of rare earth required to show a Tc ∼ 70K appears to be 25 mole percent.
About: This article is published in Materials Research Bulletin.The article was published on 1990-04-01. It has received 1 citations till now.
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TL;DR: In this paper, the authors show that the 1212 phase gets stabilized due to part substitution of Th at the Tl-site forx⩾0·25; however, Tc is low forx < 0·75.
Abstract: Superconductivity with a maximumTc, zero of 58 K forx > 0·75 has been observed in a nominal starting composition, ThxTl2Sr2Ca2Cu3Oy. X-ray data show that the 1212 phase gets stabilized due to part substitution of Th at the Tl-site forx⩾0·25; however,Tc is low forx<0·75.
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TL;DR: In this paper, stable and reproducible bulk superconductivity with an onset at 120 K and zero resistance above 100 K in the Tl-Ca/Ba-Cu-O system was reported.
Abstract: The discovery of 30-K superconductivity in the La–Ba–Cu–O system1 and 90-K superconductivity in the Y–Ba–Cu–O system2 stimulated a worldwide search for even higher-temperature superconductors. Unfortunately, most of the higher-temperature transitions reported in the past year have proved to be unstable, irreproducible, or not due to bulk superconductivity3–7. Recently, we and co-workers8,9 reported superconductivity above 90 K in a new Tl–Ba–Cu–O system, and pointed out that elemental substitutions in this system may lead to even higher-temperature superconductivity. Here we report stable and reproducible bulk superconductivity with an onset at 120 K and zero resistance above 100 K in the Tl–Ca/Ba–Cu–O system. This transition temperature is much higher than those observed for typical rare-earth-containing superconductors, and the onset temperatures are comparable to that in the Bi–Ca/Sr–Cu–O system, as reported in refs 10 and 11 (received after submission of this paper).
910 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
TL;DR: In this paper, a trilayer Cu perovskitelike units separated by bilayer TI-O units were found in T12Ca2 Ba2 Cu3 Ox with a transition to zero resistance at ≃ 125 K.
Abstract: Bulk superconductivity is reported in T12Ca2 Ba2 Cu3 Ox with a transition to zero resistance at ≃ 125 K, the highest transition temperature (Tc) yet found. Transmission electron spectroscopy shows that the unit cell is body-centered tetragonal and contains trilayer Cu perovskitelike units separated by bilayer TI-O units. (T c in this material varies from 118 to 125 K depending on preparation conditions. A high density of perovskitelike bilayer intergrowths are observed in the 118-K material, which we speculate result in the decreased (T c. A second structure containing only bilayer perovskitelike units—TI2 Ca1 Ba2Cu2Ox—is a bulk superconductor with Tv ranging from 95 to 108 K.
441 citations
TL;DR: Two superconducting phases, Tl-Ca-Ba-Cu-O system and 2122, both with onset T/sub c/ near 120 K and zero resistivity at 100 K, have been isolated from samples in the Tl/ sub 2/Ca/sub 1/Ba/sub 2/Cu/sub 3/O/sub 10/..mu../sub delta/ system.
Abstract: Two superconducting phases, ${\mathrm{Tl}}_{2}$${\mathrm{Ca}}_{2}$${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{10+\mathrm{\ensuremath{\delta}}}$ (2223) and ${\mathrm{Tl}}_{2}$${\mathrm{Ca}}_{1}$${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{2}$${)}_{8+\mathrm{\ensuremath{\delta}}}$ (2122), both with onset ${\mathrm{T}}_{\mathrm{c}}$ near 120 K and zero resistivity at 100 K, have been isolated from samples in the Tl-Ca-Ba-Cu-O system. The new 2223 superconductor has a 5.40\ifmmode\times\else\texttimes\fi{}5.40\ifmmode\times\else\texttimes\fi{}36.25-A${\mathrm{\r{}}}^{3}$ pseudotetragonal unit cell. The 2122 superconductor, which appears to be structurally related to ${\mathrm{Bi}}_{2}$${\mathrm{CaSr}}_{2}$${\mathrm{Cu}}_{2}$${\mathrm{O}}_{8+\mathrm{\ensuremath{\delta}}}$, has a 5.44\ifmmode\times\else\texttimes\fi{}5.44\ifmmode\times\else\texttimes\fi{}29.55-A${\mathrm{\r{}}}^{3}$ pseudotetragonal subcell. The 2223 phase is probably related to 2122 by the addition of extra calcium and copper layers.
368 citations
IBM1
TL;DR: Variations in the transition temperatures in the double- and triple-CuO/sub 2/-layer compounds are observed to correlate with increased densities of intergrowths of related structures.
Abstract: We describe the structures and superconducting properties of six compounds in the Tl-Ca-Ba-Cu-O system of the general form, Tl/sub m/Ca/sub inr-1/Ba/sub 2/Cu/sub n/O/sub 2(//sub n//sub +1)+//sub m/, where m = 1 or 2 and n = 1, 2, or 3. One of these compounds displays the highest known superconducting transition temperature, T/sub c/approx. =125 K. The structures of these compounds consist of copper perovskitelike blocks containing 1, 2, or 3 CuO/sub 2/ planes separated by one or two Tl-O layers and thus form a model family of structures in which both the size and separation of the copper oxide blocks can be independently varied. The superconducting transition temperature increase with the number of CuO/sub 2/ planes in the perovskitelike block for both the Tl-O monolayer and bilayer compounds. For each pair of compounds (m = 1,2) with the same number of CuO/sub 2/ planes (same n), the transition temperatures are similar but are consistently 15--20 K lower in the material with single Tl-O layers. Variations in the transition temperatures in the double- and triple-CuO/sub 2/-layer compounds are observed to correlate with increased densities of intergrowths of related structures.
224 citations