SUPERCONDUCTIVITY AT 40 K IN THE 1212 SYSTEM (PB1-XVX)SR2(CA1-ZYZ)CU2O7-DELTA

Samples of nominal composition (Pb1-xVx)Sr2(Ca1-zYz)Cu2O7-delta (0.1 l ess-than-or-equal-to x less-than-or-equal-to 0.7, 0 less-than-or-equal -to z less-than-or-equal-to 1) synthesised at 950-degrees-C in air wer e investigated. None of the as-prepared samples and of the samples pos t-treated in oxygen was superconducting. Some of the samples post-trea ted in argon at 500-degrees-C exhibited superconductivity; the main ph ase of the sample with the nominal composition (Pb0.7V0.3)Sr2(Ca0.4Y0. 6)Cu2O7-delta had a tetragonal unit cell with a = 3.822 angstrom, c = 11.818 angstrom. This sample showed a T(c,onset) of 40 K as measured b y the temperature dependence of the resistance.