INFLUENCE OF OXYGEN AND STRONTIUM CONTENT ON THE PR2-YSRYCUO4-DELTA SYSTEM

Samples of the Pr2-ySryCuO4-delta system have been prepared with accur ate control of the oxygen content. T'-T--T-Sr2CuO3 single phases are only obtained in air for y = 0, 0.4, 1, and 2, respectively. The micro structural study indicates that oxygen vacancies are randomly disorder ed for y = 0.4 (Pr1.6Sr0.4CuO3.94) but an incommensurable modulated st ructure appears for y = 1 (PrSrCuO3.6) as a consequence of ordering of anionic vacancies along [110]. Two new materials are obtained when ai r-synthesized materials are annealed under oxygen atmosphere. For y = 0.45, an orthorhombic T- phase is isolated. For y = 1, a material sho wing ordered oxygen vacancies in the basal Cu-O planes is described. ( C) 1995 Academic Press, Inc.