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 degrees C. SnCl4 . xH(2)O 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 degrees 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 degrees 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 degrees 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 greater than or equal to 600 degrees C for 2h. The product was identified as pseudo-cubic BaSnO3 with lattice parameter a(0) = 0.4118 +/- 0.0003 nm. The powder formed at 800 degrees C consisted of faceted microcrystals 80-100 nm in size. (C) 1998 Elsevier Science B.V. All rights reserved.