Superconducting Properties of Ge Substitution for the Bi Site in the 2212 Phase of Bi-Sr-Ca-Cu-O Superconductors

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J. Korean Ceram. Soc. > Volume 37(8); 2000 > Article

Journal of the Korean Ceramic Society 2000;37(8): 787.

Bi계 산화물 초전도체 2212상에 있어서 Bi 자리에 Ge 치환에 따른 초전도 특성

신재수, 이민수¹, 최봉수¹, 송승용², 송기영²

대전대학교 이과대학 전자물리학과
¹대전산업대학 정보통신컴퓨터공학부
²한남대학교 이과대학 광·전자물리학과

Superconducting Properties of Ge Substitution for the Bi Site in the 2212 Phase of Bi-Sr-Ca-Cu-O Superconductors

ABSTRACT

Samples with the nominal composition, Bi2-xGexSr2CaCu2O8＋$delta$ (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) were prepared by the solid-state reaction method. We have studied the effect of substitution Ge for Bi and investigated the superconducting properties by changing oxygen content with Ge substitution. It was found that temperature difference, ΔK, between TCon and TCzero was considerably smaller in the samples prepared by the intermediate pressing method than that in the samples by the solid-state reaction method. We found the solubility limit of Ge to the 80 K single phase was around x=0.3. Within the solubility limit, lattice constant c decreased with the increase of x. In the region of the 80K single phase, the onset critical temperature TCon increased and excess oxygen content decreased with increase of x.

Key words: Bi-Sr-Ca-Cu-O superconductors, 2212 phase, Ge substitution, Oxygen content