Fabricating Uniform Tetragonal Barium Titanate Nanocrystals via Sand Milling Assisted by an Innovative Two-Step Calcination

摘要

Sand-milling machine was firstly utilized to crush and disperse the raw materials. A homogenous and well-dispersed mixture of TiO_2 and BaCO_3(<30nm) was obtained. The solid state reaction temperature can be reduced by 200°C for nano-sized reactants compared with coarse ones. In order to increase tetragonality of nano-sized BaTiO_3, an innovative two-step calcination method, which includes solid state reaction process between reactants at a low temperatureT_1 and phase transition process at ahigh temperatureT_2, was subsequently adopted.The microstructure evolution of BaTiO_3 by two-step calcination was investigated as a function of T_2 and corresponding dwelling time t_2. Pure-perovskite BaTiO_3 nano-powders with the mean particle size as small as 75nm and tetragonality (c/a ratio) higher than 1.0096could be fabricated by two-step calcination through altering T_2 and/or its dwelling time t_2.