SMBA2CU3O7-DELTA CERAMICS PROCESSED UNDER OXYGEN-PRESSURE OF 250 BAR - ENHANCEMENT OF INTRAGRAIN SUPERCONDUCTING PROPERTIES

Polycrystalline samples of SmBa2Cu3O7-delta have been processed under oxygen pressure of 250 bar. Several of their properties typical for hi ghly oxygenated ''123'' phases were revealed: T-c=96 K as measured by ac magnetic susceptibility, high orthorhombic distortion of the unit c ell, negative thermopower at room temperature, an exceptionally high s pecific-heat jump at T-c, highly irreversible magnetization at 4.2 K, and almost 100% diamagnetic signal at 77 K. Surprisingly, the value of electrical resistivity in the normal slate and its temperature depend ence were characteristic for semiconducting materials: The superconduc ting transition was observed as a sharp drop followed by a long tail, which aas strongly dependent on the measuring current. Thus, SmBa2Cu3O 7-delta processed under an elevated oxygen pressure revealed intragrai n properties similar to that of the best YBa2Cu3O7-delta samples, howe ver, poor intergrain electrical conductivity was observed.