New route for preparing BaTiO3 nanometer powders

Abstract

In view of achieving better control over physical and chemical characteristics, there is considerable interest in evaluating new methods for the synthesis of BaTiO3 (BT) powders, and a great effort has been devoted to the development of new methods [1–6]. In this work, a rheological phase reaction method was introduced to synthesize BT nanometer powders of which structure was studied at room temperature. Rheological phase reaction method is a process of preparing compounds or materials from solid–liquid rheological mixture. That is, the solid reactants were fully mixed in a proper molar ratio, made up by adding a proper amount of water or other solvents to a solid–liquid rheological body in which the solid particles and liquid substance were uniformly distributed. Then after reaction under suitable conditions, the product was obtained. Under the solid-liquid rheological state, many substances have new reaction properties. Comparing with other methods, the one mentioned in this paper has two merits; first, the whole process is simple, soft, and green, and second, the Ba/Ti ratio was easily controlled at 1:1. The BT nanometer powders were prepared by thermal decomposition of its peroxide precursor. In order to prepare peroxide precursor, commercially available Ba(OH)2·8H2O (AR, purity >99%), H2TiO3·5H2O (AR), H2O2 solution (AR, >30%), and CO(NH2)2 (AR, purity >99%) were used as starting materials. Firstly, Ba(OH)2·8H2O (0.01 mole) and H2TiO3·5H2O were mechanically milled homogeneously in Ba/Ti molar ratio of 1.01:1, and then the H2O2 solution with CO(NH2)2 dissolved into it was added in amounts of 2.5 times in molar of Ba(OH)2·8H2O. The mixture soon became solid-liquid rheological state by slightly milling. As a result, the peroxide precursor was obtained after 10 min at room temperature [7]. In this experiment, first, H2O2 is