Bi_2(Sr_<1-x>Ca_x)_2(Ca_<1-y>Y_y)Cu_2O_δの合成と超伝導転移

概要

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Single phase Bi_2(Sr_<1-x>Ca_x)_2(Ca_<1-y>Y_y)Cu_2O_δ is successfully prepared in the range of 0≦x≦0.8 and 0≦y≦0.6 by a solid state reaction in air. The optimal sintering temperature for forming the single phase is reduced from 875℃ to 800℃ with substitution of Y in the Ca site or with increased Ca in the Sr site. The lattice parameter c reduced from 3.081 to 3.017nm by substituting Ca with Y and/or Sr with Ca. Bi_2(Sr_<1.0>Ca_<0.0>)_2(Ca_<0.8>Y_<0.2>)Cu_2O_δ, is superconducting after heat treatment either in Ar or O_2 while the phases Bi_2(Sr_<0.6>Ca_<0.4>)_2(Ca_<0.8>Y_<0.2>)Cu_2O_δ, Bi_2(Sr_<1.0>Ca_<0.0>)_2(Ca_<0.4>Y_<0.6>)Cu_2O_δ and Bi_2(Sr_<0.4>Ca_<0.6>)_2(Ca_<0.4>Y_<0.6>)Cu_2O_δ are superconducting only after oxygenation. The oxygen stability and optimum heat treatment temperature for superconductivity depend on the Sr/Ca and Ca/Y ratios in Bi_2(Sr_<1-x>Ca_x)_2(Ca_<1-y>Y_y)Cu_2O_δ.
社団法人日本セラミックス協会の論文
2005-05-01