Solid Solubility of Cerium in BaTiO3

Incorporation of Ce into the BaTiO{sub 3} 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 (XRPI). The experimental results were used to decide among various theoretically possible formulas of Ce-BaTiO{sub 3} solid solutions. Highly Ce-doped BaTiO{sub 3} specimens, synthesized by mixed oxide technology, were prepared in ambient air or in a flow of a gas mixture of 92% Ar-8% H{sub 2} inch at 1200 and 1400{degrees}C. When fired in air, cerium could be incorporated into the BaTiO{sub 3} perovskite lattice as Ce{sup 4+} at Ti sites or/and as Ce{sup 3+} at Ba sites, depending on the starting composition. During firing in a reductive atmosphere Ce is incorporated exclusively as Ce{sup 3+} at the Ba sites. A broad solid solubility region between the Ba{sub 1-x}Ce{sub x}{sup 3+}Ti{sub 1-x}{sup 4+}Ti{sub x}{sup 3+}O{sub 3} solution and the Ti-deficient Ba{sub 1-x}Ce{sub x}{sup 3+}Ti{sub 1-x/4-2 {delta}}Ti{sub 2{delta}}(V{sub Ti}){sub X/4}O{sub 3-{delta}} solution was detected.