Chemical coprecipitation of mixed (Ba+Ti) oxalates precursor leading to BaTiO3 powders

A chemical coprecipitation route is developed to synthesize a mixed oxalates {BaC2O4 + TiO(C2O4)(H2O)(2)} precursor. In this route, titanyl oxalate, TiOC2O4. nH(2)O is prepared by reaction between alcoholic solutions of butyl titanate monomer and oxalic acid. This was further converted into soluble sodium titanyl oxalate, Na2TiO(C2O4)(2) by reaction with sodium oxalate soution. The anionic TiO(C2O4)(2)(2-) species (stable over narrow pH range) thus produced are destabilized by maneuvering pH conditions with the addition of aqueous solution of barium acetate to form insoluble TiOC2O4(H2O)(2) and oxalic acid. The in-situ regenerated oxalic acid reacts with Ba2+ ions to precipitate BaC2O4 simultaneously. The mixed oxalate [BaC2O4 + TiOC2O4(H2O)(2)] on pyrolysis in air produced BaTiO3 powders. Various physicochemical techniques were used to characterize the mixed oxalate and BT powders. The results related to synthesis and characterization are discussed in this paper. (C) 1999 Elsevier Science S.A. All rights reserved.