SOLID SOLUBILITY OF CERIUM IN BATIO3

Incorporation of Ce into the BaTiO3 lattice was studied by quantitativ e wavelength dispersive spectroscopy-electron probe microanalysis (WDS /EPMA) in combination with scanning electron microscopy (SEM) and X-ra y powder diffractometry (XRPD). The experimental results were used to decide among various theoretically possible formulas of Ce-BaTiO3 soli d solutions. Highly Ce-doped BaTiO, specimens, synthesized by mixed ox ide technology, were prepared in ambient air or in a flow of a gas mix ture of 92% Ar-8% H-2 at 1200 and 1400 degrees C. When fired in air, c erium could be incorporated into the BaTiO3 perovskite lattice as Ce4 at Ti sites or/and as Ce3+ at Ba sites, depending on the starting com position. During firing in a reductive atmosphere Ce is incorporated e xclusively as Ce3+ at the Ba sites. A broad solid solubility region be tween the Ba1-XCeX3+Ti1-X4+TiX3+O3 solution and the Ti-deficient Ba1-X CeX3+Ti1-X/4-2 delta4+Ti2 delta3+(V-Ti)(X/4)O-3-delta solution was det ected. (C) 1996 Academic Press, Inc.