Preparation and Dielectric Property of BaTiO<sub>3</sub> Nanoparticles by Salt-Assisted Spray Pyrolysis

Abstract

BaTiO3 nanopowders were prepared by salt-assisted spray pyrolysis using a flux of KNO3 and NaNO3. Compounds of metal sources are thermally decomposed in the melting flux. Some flux mixtures make a eutectic composition because of the reduced melting point of the flux. The optimum temperature for the preparation of BaTiO3 nanoparticles was 700 °C. When both KNO3 and NaNO3 were used as the flux, the average particle size of the BaTiO3 powders was 40 nm, and the particle distribution was broad. On the other hand, when only KNO3 was used, the average size of BaTiO3 powders was 60 nm, and the particle distribution was narrow. This suggested that the sodium ions in the BaTiO3 nanoparticles led to a broad particle distribution. X-ray diffraction (XRD) revealed that all the diffraction peaks were in agreement with the crystal phase of BaTiO3. The relative density of the sintered body of BaTiO3 powders was 87 %. The relative dielectric constant of the sintered body was 1180, and the dielectric loss (tanδ) was 0.023 at room temperature. This suggested that the residual potassium ions in the BaTiO3 nanoparticles led to a reduction in the relative density and dielectric constant.