Solvothermal synthesis of nano-sized tetragonal barium titanate powders

Using EtOH as a solvent, we successfully synthesized tetragonal barium titanate (BT) powders of 50∼100 nm size. The particle size was dependent on the feedstock concentration: The higher the concentration, the larger the particle size. The lattice parameters and the relative amounts of tetragonal and cubic phases were determined using Rietveld refinement. As a result, the amount of the tetragonal phase decreased with a reduction in particle size. However, the mole percent of tetragonal phase exceeded 50% even with a 58 nm powder. In order to confirm the hydroxyl ion incorporation, the powder was heat-treated at 500 °C for 1 h, after which no intra-pores could be observed with a TEM, implying that the particles rarely contained hydroxyl ions in their lattice.