Low-temperature paraelectric–ferroelectric phase transformation in hydrothermal BaTiO3 particles

We report the synthesis of tetragonal sub-micron barium titanate particles through a low-temperature solvothermal treatment. Effort has been concentrated on the variation of particle characteristics including particle size and c/a ratio, as a function of treatment conditions. The tetragonality of the treated BaTiO3 particles increased from 30% to 80%, confirmed by X-ray diffraction and differential scanning calorimetry. No appreciable change in particle morphology was observed after the treatments. Extraction of the lattice hydroxyls and consequential reduction of porosity were believed to be the cause of the tetragonality raise, as confirmed by infrared spectroscopy, solid-state nuclear magnetic resonance and specific surface area investigation. This work presents a practical and simple route for preparing freestanding tetragonal BaTiO3 particles.