COPPER DEFICIENCY IN YBA2CU3O7-X CERAMICS, TEXTURED AND SINGLE-CRYSTALS

Copper deficiency is studied in YBa2Cu3O7-x phase. We compare polycrys tals formed by sintering with textured and single crystals. The experi mental method uses electron probe micro-analysis and X-ray structural determinations on single crystals. We show that YBa2Cu3O7-x, phase acc ommodates Cu deficiency up to several percent. Copper vacancies are lo cated at the Cu(1) site (in the chains). Copper deficiency is evidence d when a liquid phase is involved in the chemical process. The implica tions of copper vacancies on the physical properties has probably to b e reconsidered in future. (C) 1998 Elsevier Science S.A. All rights re served.