Microstructural development of BaTiO3powders synthesized by aqueous methods

Abstract
The hydrothermal growth of perovskite BaTiO3powders has been studied by transmission electron microscopy. The growth is carried out under high alkaline conditions (pH — 14) achieved with Ba(OH)2. Anatase (TiO2) is used as a titanium source. The perovskite BaTiO3nucleates heterogeneously on anatase TiO2 particles with an epitaxial relationship of (001)TiO2‖ (001)BaTiO3and [010]TiO2‖ [010]BaTiO3. This epitaxial relationship preserves the parallel alignment of the oxygen octahedra between the structures. A mosaic misorientation between (001)TiO2and (001)BaTiO3along 〈110〉 is seen in this relationship due to the lattice mismatch between TiO2and BaTiO3. After complete conversion of the anatase to BaTiO3, the BaTiO3particles develop into {111} octahedrons with ∼10 nm {001} and {110} microfacets on the {111} faces. This evolution suggests that {111} becomes the stable crystallographic facet for BaTiO3under highly alkaline conditions.

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