フッ素を添加したBi(Pb)-Sr-Ca-Cu-O超伝導体の組織学的研究

概要

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A F-doped Bi(Pb)-Sr-Ca-Cu-O superconductor shows a higher T_c value than that without F doping in AC susceptibility measurement. Specimens were sintered in two stages. The doping of CaF_2 in starting powders caused a considerable amount of Ca_2PbO_4 as an intermediate phase on the first sintering, which eventually resulted in the formation of Pb-enriched Ca_2CuO_3 and then the enhancement of the 2223 phase during the second sintering. The EPMA results revealed that Pb is mostly trapped in Ca_2PbO_4 after the first sintering and incorporated in the grains of the 2223 phase after the second sintering. F exists in finely distributed SrF_2 among the grains. It is made clear according to DTA that the temperature range for so-called partial melting is lowered and widened, i.e. the optimum synthesizing temperature for the 2223 phase is lower than 840 ℃.
社団法人日本セラミックス協会の論文
1992-07-01