Superconductivity in a new NdBa2Ca3Sr4Cu5Ox system
TL;DR: In this paper, a new compound, NdBa2Ca3Sr4Cu5Ox, has been synthesized using the conventional solid state reaction technique, which was characterised by powder XRD, electrical resistivity, ac susceptibility and dc magnetisation studies.
Abstract: A new compound, NdBa2Ca3Sr4Cu5Ox, has been synthesised using the conventional solid state reaction technique. The material was characterised by powder XRD, electrical resistivity, ac susceptibility and dc magnetisation studies. The results of powder X-ray diffraction show that the structure is pseudo orthorhombic, having unit cell dimensions a = 5.47 A, b = 5.46 A and c = 14.58 A. Magnetisation studies on a SQUID magnetometer showed a superconducting transition at 52 K. This was confirmed by the measurements of electrical resistance and ac susceptibility of this sample, which also showed superconductivity at 52 K. Details of preparation and characterisation are discussed.
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TL;DR: In this paper, superconducting studies have been carried out in the new high TC (50-65K) system (RE)Ba2Ca3Sr4Cu5OX [(RE) 12345] with RE=Gd, Ho&Dy.
Abstract: Superconducting studies have been carried out in the new high TC (50–65K) system (RE)Ba2Ca3Sr4Cu5OX [(RE) 12345] with RE=Gd, Ho&Dy. The unit cell dimensions are of the order of a=5.44 °A, b=5.46°A and c=14.62°A. The data above the diamagnetic onset and below the upturn temperature due to ordering were analyzed to yield the effective magnetic moments (Peff) of the rare earth ions.
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IBM1
TL;DR: In this paper, Ba−La−Cu−O system, with the composition BaxLa5−xCu5O5(3−y) have been prepared in polycrystalline form, and samples with x=1 and 0.75,y>0, annealed below 900°C under reducing conditions, consist of three phases, one of them a perovskite-like mixed-valent copper compound.
Abstract: Metallic, oxygen-deficient compounds in the Ba−La−Cu−O system, with the composition BaxLa5−xCu5O5(3−y) have been prepared in polycrystalline form. Samples withx=1 and 0.75,y>0, annealed below 900°C under reducing conditions, consist of three phases, one of them a perovskite-like mixed-valent copper compound. Upon cooling, the samples show a linear decrease in resistivity, then an approximately logarithmic increase, interpreted as a beginning of localization. Finally an abrupt decrease by up to three orders of magnitude occurs, reminiscent of the onset of percolative superconductivity. The highest onset temperature is observed in the 30 K range. It is markedly reduced by high current densities. Thus, it results partially from the percolative nature, bute possibly also from 2D superconducting fluctuations of double perovskite layers of one of the phases present.
10,272 citations
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: In this paper, a family of superconducting copper oxides in which the carriers are electrons was discovered, with the formula Ln2−xCexCuO4−y, where Ln stands for lanthanides Pr, Nd or Sm.
Abstract: Since the discovery of high-temperature superconductivity in cop-per oxide compounds1, there has been much effort to understand what is required for a compound to have a high transition tem-perature (Tc). Up to now, all of the families of high-Tc copper oxide superconductors have contained two-dimensional sheets of Cu–O pyramids or octahedra, and the carriers of the superconduct-ing current have been electron vacancies, or 'holes'. By contrast, we report here the discovery of a family of superconducting copper oxides in which the carriers are electrons. The new superconductors are Ce4+-doped compounds, with the formula Ln2–xCexCuO4–y, where Ln stands for the lanthanides Pr, Nd or Sm. The compounds have the Nd2CuO4 (T′-phase) structure2, which is composed of sheets of Cu–O squares (see Fig. la). This structure has no apical oxygen atoms, in contrast to the T-phase structure with Cu–O octahedra (Fig. 1b), as observed in La2–xSrxCuO4 (refs 1, 2), and the T*-phase structure with Cu–O pyramids (Fig. 1c), as in Nd2–x–z Cex Srz CuO4 (ref. 3 and Y. T. et al., manuscript in preparation).
1,402 citations
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