Synthesis and Characterization of Barium Lanthanum Titanates

Abstract

Ternary compounds in the system BaO—TiO 2 —La 2 O 3 were prepared by the solid‐state reaction technique at temperatures between 1300° and 1400°C using precursor oxides as the starting materials. In an alternative processing technique, BaTiO 3 was reacted with appropriate proportions of prefabricated lanthanum titanates at 1350°C to obtain the compounds. Two compounds were identified in the TiO 2 ‐rich region of the system. The X‐ray powder diffraction pattern of a compound with a chemical composition BaLa 2 Ti 3 O 10 (BaO·La 2 O 3 ·3TiO 2 ) is indexed on the basis of an orthorhombic unit cell with a = 7.665 × 10 −1 nm, b = 28.524 × 10 −1 nm, and c = 3.876 × 10 −1 nm. The other compound, which has a chemical composition Ba 4 La 8 Ti 17 O 50 (BaO·La 2 O 3 ·4.25TiO 2 ) occurs in a narrow homogeneity range within the system. The X‐ray powder diffraction pattern of the compound is indexed on the basis of an orthorhombic unit cell with a = 12.317 × 10 −1 nm, b = 22.394 × 10 −1 nm, and c = 3.881 × 10 −1 nm. Both the compounds are compatible with BaTiO 3 and form pseudobinary joins with BaTiO 3 in the system BaO—TiO 2 —La 2 O 3 .