Preparation of barium titanate by oxalate method in ethanol solution

Abstract

Barium titanyl oxalate was prepared by addition of ethanol solution in oxalic acid to barium-titanium mixed aqueous solution at room temperature. The influence of various factors such as starting reagents, reaction temperature and titration rate were investigated. The use of TiCl4 or TiO(NO3)2 solution as starting reagents, respectively, produced an amorphous or crystalline oxalate regardless the reagent for Ba. The crystalline oxalate has a different structure from the one reported previously. It may be speculated that this originates from the deficiency of water of crystallization. Chemical formula of the oxalate obtained in the present study could correspond to BaTiO(C2O4)23H2O as indicated by TGA experiments. The oxalate, which was prepared by use of Ba(NO3)2 and TiO(NO3)2 as starting reagents and by low reaction-temperature and rapid titration-rate of ethanol solution of oxalic acit to BaTi mixed aqueous solution, converted to stoichiometric barium titanate having a perovskite-type structure with tetragonal symmetry. The barium titanate obtained consists of very fine particles of size around 0.3 μm and shows translucency after hot pressing at 1150°C for 3 hr at 600 kg/cm2.