A New Compound in the System BaO-TiO₂-Cr₂O₃

Abstract

In order to elucidate the phase relation of pseudo-ternary system BaO-TiO₂-Cr₂O₃ in an oxydizing atmosphere, the reaction of BaO-TiO₂ compounds with Cr₂O₃ was investigated by chemical, thermal and X-ray diffractometric analyses.
Both of 2BaO⋅TiO₂ and BaO⋅TiO₂ react with Cr₂O₃ to form BaCrO₄ as a product, the maximum values of the fractional formation to BaCrO₄ were 90 and 80% of theoretical, respectively, and the resulting TiO₂ was not detected in the process of the reaction, both of which indicated a new compound with about 1/5 of the molar ratio BaO/TiO₂ would be produced.
As a result of an investigation by the disappearing-phase method, it could be concluded that the new compound may be represented as BaO⋅5TiO₂⋅Cr₂O₃ (tetragonal, a₀=7.11Å, c₀=8.50Å) isomorphous with BaO⋅5TiO₂⋅Fe₂O₃ (tetragonal, a₀=7.14Å, c₀=8.54Å).