Sol–gel synthesis of strontium titanate powders of various compositions

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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.