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Single crystals d YBa2Cu3Oe+,, Y0.SGd0.5Ba2CU30e+y and GdBazCu3%+, have been prepared by the self-flux method, and their growing conditions have been optimized through several trial runs. A post-annealing of as-grown single aystals in high-pressure (-150 bar) pure oxygen proves to be very effective in increasing their T, Over 90 K h u e back diffraction patterns confirmed the goo6 quality o f the samples. The morphology, composition analysis and the magnetic properties of these crystals are also reported.

The oxide superconductor Bi1.7Pb0.3Sr2−xAgxCa2Cu3Oy has been synthesized under the ordinary pressure. The x-ray diffraction spectra of these specimens show the presence of only 2212 phase when x<0.4, and the transition temperature achieved 99 K. With the x increase, the structure of sample transfers to 2223 phase. The investigation indicates that substitution of Sr2+ by Ag1+ increases the distance between layers. This may respond to Tc increase in 2212 phase and 2223 phase form at a relatively low temperature.

Influence of normal particle on crack and JC and the effect of pinning on anisotropy of JC a r e discussed.