Preparation of pure perovskite-type BaSnO₃ powders by the polymerized complex method at reduced temperature

Cubic perovskite-type pure barium stannate, BaSnO₃, powders were prepared using the polymerized complex technique at the relatively low temperature of 600°C. SnCl₄·xH₂O was first dissolved in ethylene glycol (EG) and anhydrous citric acid (CA) was then added. After complete dissolution, BaCO₃ powder was added and the mixture was stirred at 80°C for several hours until the solution became transparent, demonstrating the presence of Ba²⁺- and Sn⁴⁺-citric acid complexes. This solution, with molar ratio Ba/Sn/CA/EG = 1:1:10:40, was heated at 130°C to produce a yellowish transparent resin without any precipitation via polymerization with citric acid and ethylene glycol including the complexes. Pyrolysis of the resin at 350°C yielded a powder precursor of BaSnO₃. X-ray diffraction and Raman analysis indicated the formation of pseudo-cubic BaSnO₃ when the barium-tin precursor was heat treated in air at ≥ 600°C for 2 h. The product was identified as pseudo-cubic BaSnO₃ with lattice parameter a₀ = 0.4118±0.0003 nm. The powder formed at 800°C consisted of faceted microcrystals 80-100 nm in size.