Preparation of Nanocrystalline Ba3(Cai.i8Nbi 82)O9_<5 Powder by UsingCitrate Sol-Gel Method

Ba3(Ca1.18Nb1.82)O9-δ(BCN18) powders were synthesized by using a wet chemical method from a mixture of all water-soluble compounds including Ba, Ca and Nb-citrate. Heating a mixed aqueous solution with the molar ratio of Ba:Ca:Nb:citric acid=3:l.18:1.82:12 produced a light green gelatinous viscous matter without any precipitation, then evaporating, drying and calcinating were conducted. The obtained gels were characterized by TG-DTA, XRD and TEM. The experimental results show that the heating temperature is 750℃ for getting the powder and the average particle size is about 50nm. Furthermore a pure BCN18 phase with a complex perovskite structure forms at 1000℃,it is lower about 600℃ than that reported by using the traditional solid-reaction method. The citrate sol-gel method is more practical and ascendant than the wet-chemical method used to the alcohol salt system reported in present literature.