Bi_2−xPb_xSr₂Ca₂Cu₃O_y superconducting samples with 0<x<0·3 have been synthesized and characterized using X-ray powder diffraction.T_c and superconducting volume fraction have been measured using a.c. magnetic susceptibility, d.c. electrical resistivity as well as X-band microwave surface resistance in the normal state. The data indicate the growth of the highT_c (2223) phase with corresponding reduction of the lowT_c (2122) phase with increasingx, up to 0·25. Beyond this value ofx there is a slight deterioration of the superconducting behaviour.

Magnetization was measured on Pr-doped YBa₂Cu₃O_7−y for fields up to 5·5T. The paramagnetic behaviour is correlated to the free ion values of Pr³⁺ and Pr⁴⁺. Hysteresis experiments were done for superconducting composition for fields up to 1100 Gauss. The intragrain critical current density is calculated using Bena’s formula.

The structural instability in Ti rich compositions of Nb-Ti alloy system, which leads to various anomalies in the normal and superconducting state properties, has been extensively studied in bulk samples in the past. In this paper we report the formation of thin films of several compositions in the Ti rich region of this alloy system by RF magnetron sputtering and investigation of their electrical properties. Compositional analysis of two representative films was carried out by the RBS technique and the compositions agreed to within 2% of the targeted values. The anomalous variations in the electrical properties characteristic of the bulk, which can be ascribed to the structural instability related to the formation of athermal ω-phase, are also observed in thin films.