Combustion-synthesis of SrTiO3Part II. Sintering behaviour and surface characterization

Nanocrystalline powders of SrTiO3 prepared via combustion-synthesis were sintered at 800 resp. 1000°C. The powders exhibited different grain growth velocities which were measured via X-ray diffraction (XRD). The existence of different SrCO3-species was found by Fourier-transform infrared spectroscopy (FTIR). These could be assigned either to bulk- or surface-SrCO3-species which could be proved by their different decomposition temperatures in thermogravimetry combined with mass spectrometry (TG/MS). A dependence between the grain growth velocities and the existence of surface-SrCO3-species was found: samples which develop surface carbonate species for longer times during sintering will exhibit faster growth rates than samples which showed these species for shorter times. The surfaces of the crystallites are predominantly SrO-terminated which is in agreement with former results of other authors. The strong variations in sintering behaviour caused by only small differences between various samples are typical for nanocrystalline materials, they may be prepared by sol–gel or combustion-synthesis.