PURPOSE: To suppress the lowering of critical temp. Tc and critical current density Jc by incorporating a prescribed amt. of Ir into an oxide compsn. contg. Bi, Sr, Ca and Cu as essential components.
CONSTITUTION: Starting materials contg. Bi, Sr, Ca and Cu such as oxides and carbonates are mixed in 2:2:1:2 or 2:2:2:3 atomic ratio of Bi:Sr:Ca:Cu to obtain a mixture. Pb is substd. for part of Bi in the mixture if necessary. An Ir compd. convertible into Ir as a simple substance after firing, e.g. IrO2 is then added to the mixture by 0.1-2wt.% and they are uniformly mixed to obtain a starting material mixture. This mixture is fired at 810-900°C for 5-50hr when Pb is not contained, and at 845±20°C for 20-200hr when Pb is contained, to produce an oxide superconductor.
KUWAJIMA HIDEJI
YAMANA SHOZO
