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

抄録

Substitution of Cd for Ca in Bi₂Sr₂Ca₂Cu₃O_y 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 Bi₂Sr₂Ca_2-xCd_xO_y at 870°C for 5 hr in air yielded a superconducting phase with c_o= 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 c_o = 2.5 nm was formed instead of c_o = 3.0 nm phase.