Preparation of MgO-coated BaTiO_3 particles through a surface-induced precipitation method

摘要

The effect of particle size of BaTiO_3 on the preparation of magnesia-coated BaTiO_3 particles was studied through a surface-induced precipitation method. MgO-coated BaTiO_3 particles were prepared by a homogeneous precipitation method using MgCl_2 centre dot 6H_2O and urea. Particle sizes of starting BaTiO_3 powders were approx 30 and approx 400 nm, respectively. Amorphous magnesia precursor with approx 10 nm was heat treated and transformed to crystalline MgO. Crystallization of MgO was observed at the temperature range between 600 and 700 deg C. Zeta potentials were all negative such as -2 mV for MgO, -18 mV for 400 nm BaTiO_3 and -22 mV for 30 nm BaTiO_3 at pH 7.0. The MgO-coating layer was observed on BaTiO_3 particles with approx 400 nm, whereas none of the coating layer was observed on BaTiO_3 with approx 30 nm. According to calculation of the total interaction potential energy, the most strong attraction energy was observed between 400 nm BaTiO_3 and MgO particles.