Solid solubility of cerium in BaTiO3

Incorporation of Ce into the BaTiO3 lattice was studied by quantitative wavelength dispersive spectroscopy-electron probe microanalysis (WDS/EPMA) in combination with scanning electron microscopy (SEM) and X-ray powder diffractometry (XRPD). The experimental results were used to decide among various theoretically possible formulas of Ce-BaTiO3 solid solutions. Highly Ce-doped BaTiO, specimens, synthesized by mixed oxide technology, were prepared in ambient air or in a flow of a gas mixture of 92% Ar-8% H-2 at 1200 and 1400 degrees C. When fired in air, cerium could be incorporated into the BaTiO3 perovskite lattice as Ce4+ at Ti sites or/and as Ce3+ at Ba sites, depending on the starting composition. During firing in a reductive atmosphere Ce is incorporated exclusively as Ce3+ at the Ba sites. A broad solid solubility region between the Ba1-XCeX3+Ti1-X4+TiX3+O3 solution and the Ti-deficient Ba1-XCeX3+Ti1-X/4-2 delta4+Ti2 delta3+(V-Ti)(X/4)O-3-delta solution was detected. (C) 1996 Academic Press, Inc.