[en] The composition dependence of superconductivity and crystal structure in La(Ba_1-chiCa_chi)₂Cu₃O_7-y system was determined by the resistivity measurements and X-ray diffraction analysis. The superconducting transition temperature is raised with the increase of Ca content till chi=0.6, at which the zero resistance temperature of the sample is 81.5Κ. In the meanwhile, the crystal structure of the sample changed from tetragonal (chi=0) to orthorhombic structure (chi=0.2,0.4,0.6). With further increase of Ca content, the superconductivity decrease for the sample of chi=0.8 with mixed phases including the orthorhombic oxygen-deficient perovskite-like (ODP) structure and no superconducting transition is found at 4.2Κ for the sample of chi=1 without the ODP structure. A possible explanation of these experimental results is given

[en] The magnetic properties of YBa₂Cu₃O/sub z/ with different values of z in the temperature range 1.5--300 K were measured and compared with those of DyBa₂Cu₃O/sub z/ and EuBa₂Cu₃O/sub z/. The susceptibility data of YBa₂Cu₃O/sub z/ and DyBa₂Cu₃O/sub z/ followed the Curie--Weiss law above T/sub c/, while those of EuBa₂Cu₃O/sub z/ exhibited the Van Vleck and Frank behavior [Phys. Rev. 34, 1494 (1929)] with σ = 33. The paramagnetism persisted even below T/sub c/. The effective moment per copper ion increased as the oxygen content decreased. The results suggest that the paramagnetism in YBa₂Cu₃O/sub z/ originates mainly from the nonsuperconducting domains of the material which have disordered oxygen vacancies or have lower oxygen content than the superconducting ones

[en] The crystal structure and superconductivity of the Ba-Gd-Cu-O system are reported in this paper. The compound Ba₂Gd Cu₃Osub(g-y) has an orthorhombic distorted perovskite structure cell with parameters a = 3.909 A, b = 3.849 A and c 11.682 A. It is an excellent superconductive phase with the temperature of zero resistivity transition 94.5 K. (author)

[en] The resistance and a.c. magnetic susceptibility of BaMo⁶S⁸ have been measured under pressure. A resistance-anomaly, indicative of the reported structural transformation of the order of 145 K, was observed. Non-bulk super-conductivity with a pressure dependent signal size was induced by a quasi-hydrostatic pressure approx. = 15 kbar but not by a hydrostatic pressure up to 18 kbar down to 1.2 K. (author)

[en] Nonbulk superconductivity with a pressure-dependent signal size has been detected but only between 2 and 43 kbar in Eu_1.2Mo⁶S⁸ quasihydrostatically. The results not only shed light on the occurrence of superconductivity in this compound but also provide insight to the nature of the superconductivity observed

[en] A normal-superconducting-normal transition has been observed resistively in the granular BaPb/sub 0.75/Bi/sub 0.25/O₃ compound, while the compound remains diamagnetic to the lowest temperature investigated. This has been attributed to the decoupling of the superconducting grains at low temperature caused by the reduction of charge carriers in the grain barriers, in good agreement with the theory