Novel aqueous solution route to the low-temperature synthesis of SrBi₂Nb₂O₉ by use of water-soluble Bi and Nb complexes

Powders of SrBi₂Nb₂O₉ (SBN) were synthesized using an aqueous solution method from mixtures of all water-soluble compounds including Sr-EDTA, Bi-EDTA and Nb-citrate. Heating of a mixed aqueous solution with the molar ratio of Sr:Bi:Nb:citric acid=1:2:2:10 produced a pale-yellow gelatinous viscous matter without any precipitation, which was subsequently pyrolyzed at 300°C to give a powder precursor for SBN. The formation of a pure Perovskite ferroelectric SBN occurred when the powder precursor was heat-treated in air at temperatures higher than 650°C. A fluorite SBN formed in the 500-600°C range, which appeared to act as an intermediate phase prior to the formation of the Perovskite SBN. The environmentally beneficial aspect of the present aqueous solution route was briefly discussed.