Synthesis of nanosized β-BiTaO4 by the polymeric precursor method

Abstract

β-BiTaO4 powder was synthesized by the citrate method, using bismuth citrate and TaCl5 as precursors. The citrate gel was characterized by thermal analyses (TG and DTA), in order to determine the best polymerization temperature. The polymeric precursor is essentially amorphous and after calcination at 400 °C a mixture of tantalates, that are isomorphic to Bi3NbO7 and Bi5Nb3O15, starts to crystallize. At 600 °C, in addition to those phases, one could observe some peaks related to β-BiTaO4. Finally, at 800 °C β-BiTaO4 can be observed as a pure phase, with particle size estimated as 47 nm. The precursor polymeric method allowed obtaining β-BiTaO4 pure phase at temperatures significantly lower than those found for solid state reaction method.