Sol–gel synthesis of strontium titanate powders of various compositions

Abstract

The strontium titanates SrTiO₃, Sr₂TiO₄, Sr₃Ti₂O₇ and Sr₄Ti₃O₁₀ can be synthesized by a sol–gel method at low temperatures. The reaction between strontium acetate solution and titanium(IV) isopropoxide leads to the formation of strontium titanate gels. The gels can be converted to the strontium titanates by drying and calcination. The resulting ultrafine, phase-pure strontium titanate powders have a low impurity content. They are very sinter active above 1000 °C. The rate of densification (which considers the green densities at a given time and the theoretical densities of the titanates for the calculations) during the sintering of compacts increases as Sr₂TiO₄ < Sr₃Ti₂O₇ < Sr₄Ti₃O₁₀ < SrTiO₃. The strontium titanate gels and the titanate powders were characterized by differential thermal analysis (DTA), thermal gravimetry (TG), X-ray diffraction (XRD), scanning electron microscopy (SEM) and chemical analysis.