Superconducting properties of substituted oxides Bi2Sr2(Ca1−xYx)Cu2O8+y

Abstract The new oxides Bi 2 Sr 2 YCu 2 O 8+ y and Bi 2 Sr 2 ( Ca 1− x Y x ) Cu 2 O 8+ y have been prepared. The former compound contains 8.65 oxygen atoms per formula and crystallizes in the orthorhombic symmetry with, as lattice parameters, a = 5.431 A , b = 5.467 A and c = 30.22 A . After heating at 940°C in air, this oxide decomposes with Y 2 O 3 and Bi 2 Sr 2 CuO 6 as the main products. For 0⩽ x ⩽0.7, the Bi 2 Sr 2 ( Ca 1− x Y x ) Cu 2 O 8+ y solid solutions exhibit a superconducting transition. The critical temperature remains almost constant (85–90 K) for 0⩽ x ⩽0.30 and then decreases rapidly.