FIZIKA A 4 (1995) 3, 571-580

AN ELECTRON MICROSCOPY STUDY OF THE "CHAIN''-LAYER ORDERING IN THE YBCO-TYPE HIGH-T_c SUPERCONDUCTORS

OGNJEN MILAT
Institute of Physics of the University, Bijenička 46; POBox 304; HR-10001 Zagreb, Croatia

Dedicated to Professor Mladen Paić on the occasion of his 90^th birthday

Received 23 June 1995

Structures of a number of high-T_c superconducting cuprates related to the prototype YBCO compound, were studied by means of high resolution electron microscopy (HREM) and electron diffraction (ED). Commensurate superstructures or incommensurate modulated structures were induced by various metal atom substitutions for Cu in the ``chain''-layer and its ordering. Metal (M) and oxygen (O) atom ordering is confined mainly in the MO_1-x-"chain'' layers, while the remaining part of the crystal structure, as well as the material's superconducting features, are hardly affected.

UDC 538.945
PACS 61.10.-i, 61.14.-x, 74.72.-h

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