Bi系酸化物超伝導体(2212相)の酸素収脱着挙動と超伝導特性

概要

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Oxygen sorption-desorption behavior as well as superconducting properties were examined for four Bi-based oxides (2212 phase, Bi_<2-x>Pb_xSr_<2-y>Ca_<1+y>Cu_2O_<8+δ>: (x, y) = (0, 0), (0, 0.8), (0.2, 0), (0.2, 0.8)). Temperature-Programmed-Desorption (TPD) measurements revealed that reversible sorption and desorption of small amounts of oxygen (ca. 2-3 x 10^<-5> mol/g) were observed for all the samples below 600℃. The T_c, and lattice parameters (c) were found to change reversibly with the oxygen content. The oxygen content dependence of T_c for the y = 0 sample was quite different from that for y = 0.8, i.e., T_c increased with decreasing oxygen content in the former, while in the latter T_c decreased. On the other hand, the oxygen content dependence for x = 0 was similar to that for x = 0.2. The optimum oxygen content (hole concentration) for the highest T_c in Bi_2Sr_<1.2>Ca_<1.8>Cu_20_<8+δ> was confirmed to be δ = 0.15.
社団法人日本セラミックス協会の論文
1991-09-01