Inestigation on the Structural Transition of n-type Ceramic Superconductor, <tex>$Nd_{2-x}Ce_xCuO_{4-upsilon}$</tex> System of CBED

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J. Korean Ceram. Soc. > Volume 34(2); 1997 > Article

Journal of the Korean Ceramic Society 1997;34(2): 139.

수렴성전자회절에 의한 n-형 세라믹 초전도체 $Nd_{2-x}Ce_xCuO_{4-upsilon}$의 결정구조 전이 연구

김정식, 유광수

서울시립대학교 재료공학과

Inestigation on the Structural Transition of n-type Ceramic Superconductor, $Nd_{2-x}Ce_xCuO_{4-upsilon}$ System of CBED

ABSTRACT

Structurally, the rare earth cuprate superconductor of Nd2-xCexCuO4-$delta$ has T' structure and has been known as having a quite complicated microstructural phenomena, so far. In order to be superconductivity, both small amount of cation substitution of Nd3+ by Ce4+ and oxygen reduction are required. In the present study the crystallographic study on the structural transition for the Nd2-xCexCuO4-$delta$ crystal has been con-ducted by observing the CBED (Convergent Beam Electron Diffraction) pattern with STEM(Scanning Transmission Electron Microscope). Three different samples of Nd2CuO3,Nd1.85Ce0.15CuO4 and Nd1.85Ce0.15CuO3.965 were prepared by solid-state sintering and their CBED patterns were observed by STEM to study the structural transition accompanying the substitution of Ce and the reduction of oxygen. Experimental HOLZ lines of these samples were compared with those plotted by a computer-programmed simulation to de-termine the lattice parameter of Nd2-xCexCuO4-$delta$ crystal.

Key words: Nd-Ce-Cu-O superconductor, CBED, Crystallography, Phase transition