Synthesis and characterization of Sr 1− xMg xTiO 3 obtained by the polymeric precursor method

Abstract

Strontium titanate (SrTiO 3; STO), a semiconductor displaying the perovskite structure, has been extensively studied, both as thin films and as powders, due to its high dielectric constant, good capacitance, and other properties. In the present work, the synthesis of Mg-substituted SrTiO 3 powders was studied using the polymeric precursor method. This method, also known as the Pechini method, has many advantages such as chemical homogeneity of multicomponents at the molecular scale and a direct and precise control of stoichiometry in complex systems at relatively low temperatures. The powders were characterized by thermogravimetry (TG)/differential thermal analysis (DTA). After the heat treatment between 600 and 1000 °C, the powders were characterized by X-ray diffraction (XRD) and infrared spectroscopy (IR). Thermal analysis results indicate successive exothermic and endothermic steps. After crystallization, a single-phase material was obtained for samples containing less than 20 % of Mg. The crystallite size was nanometric and a high crystallinity was obtained. Infrared spectroscopy indicated vibration bands characteristic of carbonates and metallic oxides.