PREPARATION AND CHARACTERIZATIONS OF ULTRAFINE Sr_(0.5)Sm_(0.5)CoO_3 CERAMIC POWDER

Ultrafine Sr0.5Sm0.5CoO3 (SSC) ceramic powders with homogeneous composition were prepared via a low temperature combustion process and a coprecipitation process,respectively.The resultant SSC powders were characterized by X-ray diffraction,scanning electron microscope and energy dispersive spectroscope.The results show that the SSC particles obtained by the low-temperature combustion are near spherical and the particle size is less than 200 nm;and the particles obtained by the coprecipitation process appear a perovskite structure and the average size is 500 nm.The pressed SSC powders obtained from the low-temperature combustion and the coprecipitation process can be sintered in air at 1150 ℃ and 1200 ℃ intothe dense pellet samples,respectively.The oxygen permeation rates through the SSC dense films obtained by the low-temperature combustion and the coprecipitation process are approximately 4.61×10-7 and 4.46×10-7 mol/(s·cm2) at 900 ℃ respectively,when the flow rates of air and He are 1.12×10-4 mol/s and 1.70×10-5 mol/s,respectively.