Molten-salt synthesis of BaTiO3 powders and their atomic-scale structural characterization

Abstract

In this work, BaTiO3 powders were synthesized by molten-salt synthesis method using BaCO3, TiO2, and the eutectic salts (NaCl-KCl) as the raw materials. A systematic study indicating the effects of calcination temperature as well as the molar ratio of NaCl to KCl in the mixed salt with respect to BaCO3 -TiO2 on the microstructures of BaTiO3 powders is reported. The results showed that all the powders crystallized in a tetragonal perovskite structure, as confirmed by X-ray diffraction pattern and Raman spectra. With increasing the calcination temperature, the morphology of the as-prepared BaTiO3 powders developed from rectangular/spherical aggregates to circular or cubic shapes and the average particle size was also increased from 320 nm to 900 nm. With increasing the molar ratio of BaCO3:TiO2: NaCl: KCl, the average particle size was slightly decreased from 440 nm to 360 nm, and the morphology of the as-synthesized BaTiO3 powders transformed from rectangular and cubic shapes to sphere shapes. The chemical compositions of the as-synthesized BaTiO3 powders obtained from energy dispersive X-ray analysis are in agreement with the nominal ratios. The present results provide a generalized methodology to large-scale synthesize other perovskite transitional metal oxide powders with controllable sizes and shapes.