Perovskite-related phases in the Sr4Nb4O14-Sr5Nb4O15-SrTiO3 system

摘要

Phase relations have been investigated within the Sr4Nb4O14-Sr5Nb4O15-SrTiO3 region of the SrO-Nb2O5-TiO2 system with a view to clarifying the occurrence of perovskite-related phases, Most samples were prepared from oxide or carbonate powders heated in air at 1350 degrees C but some samples were also prepared by argon are melting. Overall phase analysis mas carried out by powder X-ray diffraction. Two phase lines contain a homologous series of layered perovskite phases, These are the Sr-n(Nb, Ti)(n)O3n+2 (4 less than or equal to n less than or equal to 7) series on the Sr4Nb4O14-SrTiO3 line and Sr-n(Nb, Ti)(n-1)O-3n (5 less than or equal to n less than or equal to 7) on the Sr5Nb4O15-SrTiO3 line. The microstructures in these homologous series were clarified by transmission electron microscopy. This revealed both ordered and disordered intergrowths of the perovskite homologues and allowed the defect microstructure of SrTiO3 in contact with the layered perovskites to be determined. (C) 1998 Academic Press. [References: 13]