STOICHIOMETRY, DEFECTS, AND ORDERING IN LEAD TANTALUM OXIDES WITH PYROCHLORE-RELATED STRUCTURES

摘要

The phase diagram in the PbO-Ta2O5 system has been reinvestigated in the Pb1.5Ta2O6.5-Pb2.44Ta2O7.44 composition range, The existence of the defect-pyrochlore cubic phase Pb15Ta2O6.5 is confirmed but the apparent solid solution previously reported in the Pb2.31Ta2O7.31-Pb2.44Ta2O7.44 composition range is shown to be due to the coherent intergrowth of defined rhombohedral phases with slightly different compositions. (C) 1996 Academic Press, Inc. [References: 20]