SYNTHESIS AND CHARACTERIZATION OF BARIUM LANTHANUM TITANATES

Ternary compounds in the system BaO-TiO2-La2O3 were prepared by the solid-state reaction technique at temperatures between 1300-degrees and 1400-degrees-C using precursor oxides as the starting materials. In an alternative processing technique, BaTiO3 was reacted with appropriate proportions of prefabricated lanthanum titanates at 1350-degrees-C to obtain the compounds. Two compounds were identified in the TiO2-rich region of the system. The X-ray powder diffraction pattern of a compound with a chemical composition BaLa2Ti3O10 (BaO.La2O3.3TiO2) is indexed on the basis of an orthorhombic unit cell with a = 7.665 x 10(-1) nm, b = 28.524 x 10(-1) nm, and c = 3.876 x 10(-1) nm. The other compound, which has a chemical composition Ba4La8Ti17O50 (BaO.La2O3.4.25TiO2) 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 x 10(-1) nm, b = 22.394 x 10(-1) nm, and c = 3.881 x 10(-1) nm. Both the compounds are compatible with BaTiO3 and form pseudobinary joins with BaTiO3 in the system BaO-TiO2-La2O3.