超急冷非晶質から作製したBi系超伝導膜の性状に及ぼすCdO添加の効果

概要

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Substitution of Cd for Ca in Bi2Sr2Ca2Cu3Oy has been studied by using rapid quenching after rapid melting technique. Amorphous materials containing a small amount of CaO phase were obtained as films with about 20 μm thickness. Annealing of the films for Bi2Sr2Ca2-xCdxOy at 870°C for 5 hr in air yielded a superconducting phase with co= 3.0 nm in the composition of x≤0.5. Tc(endpoint) increased and tailing of transition disappeared with increasing Cd contents. A maximum Tc(endpoint) value of 87 K was obtained at the composition of x=0.4. Further substitution of Cd for Ca brought about lowering in Tc, because a semiconducting phase with co = 2.5 nm was formed instead of co = 3.0 nm phase.