Precursor gel for preparation of nanocrystalline BaSnO 3 powder was synthesised by aqueous sol-gel method using Ba(OH) 2 • 8 H 2 O and Na 2 SnO 3 • 3 H 2 O as raw materials. Thermogravimetric and differential scanning calorimetric analyses of the raw materials, precursor gel and a mechanical mixture of raw materials were carried out to understand the mechanisms involved in the formation of the single phase BaSnO 3. Based on the thermal analysis, the precursor gel was calcined at 400, 800 and 1400°C for 4 h to obtain pure phase BaSnO 3 powder. X-ray diffraction pattern of the powder calcined at 1400°C was refined for atomic coordinate, lattice parameter (a = 4.1117(2) Å) and occupancies using Rietveld refinement analysis. The average crystallite size calculated from the Scherrer formula is ∼35 nm. Transmission electron micrograph of the powders confirmed that particle sizes are in range of 20-40 nm. The phase purity of the powder calcined at 1400°C was further examined by Fourier transform infrared spectroscopy. Optical properties of the BaSnO 3 powder were studied by UV-visible absorption and photoluminescence (PL) spectra. The band gap energy (3.09 eV) obtained from the Tauc plot confirmed the semiconductor nature of the powder. The CIE coordinate corresponding to PL spectrum exhibited an intense emission in the visible region.

The reaction of Ba(NO3)2 with TiO2 was studied by thermogravimetric (TG) and differential scanning calorimetric (DSC) techniques up to 1000?C and in nitrogen atmosphere. It was found that the formation of BaTiO3 takes place above 600?C and that precursor mixing time and heating rate have no effect on the reaction temperature. BaTiO3 powder was prepared by calcination of Ba(NO3)2 and TiO2 precursor mixture at 800?C for 8 h. X-ray diffraction analysis of the synthesized BaTiO3 confirmed the formation of tetragonal phase with lattice parameters a = 3.9950?0.0003? and c = 4.0318?0.0004?. Thermal analysis of the synthesized BaTiO3 powder showed weight loss within temperature range 40-1000?C of only 0.40%. This small amount of weight loss was connected with some impurity phase, and identified as BaCO3 using Fourier transform infrared (FTIR) technique.

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