Chimie douce synthesis and thermochemical characterization of mesoporous perovskite-type titanate phases

Various compositions of perovskite-type titanates were synthesised by a chimie douce synthesis method with emphasis on low synthesis temperatures. The cations were complexed by citric acid as chelating agent forming a homogeneous organic/inorganic network. The thermal decomposition of this xerogel precursor was investigated by thermogravimetric analysis (TGA). Simultaneous thermal analysis with mass spectrometry (MS) in combination with infrared spectroscopy (IR) allowed studying the precursor decomposition mechanism. The perovskite phase formation was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The citrate precursor was decomposed by two different preparation methods to evaluate the influence on the morphology and size of perovskite-type particles. The perovskite-type titanates obtained by thermal decomposition of precursors revealed well-defined mesoporous morphology. Ultrafine perovskite-type particles were also synthesized inside micro-droplets in an aerosol process using ultrasonic spray combustion (USC). This alternative preparation enhanced the specific surface area particles by a factor 3 reaching 50–60 m2/g.