Synthesis of ferroelectric nanocrystalline SrBi 2Ta 2O 9 powder by the colloid-gel process

Abstract

An innovative colloid-gel process using inorganic salts as starting materials has been successfully developed for preparing ferroelectric strontium bismuth tantalate (SrBi 2Ta 2O 9) powder. This new technique began with the preparation of a mixture of Ta(OH) 5 colloid with the aqueous solutions of strontium and bismuth cations, followed by the addition of ethylene glycol and citric acid as gel-forming reagents. During the calcination process the fluorite phase was formed as an intermediate that was subsequently converted into the SrBi 2Ta 2O 9 phase. After calcination at 750°C, pure ultrafine SrBi 2Ta 2O 9 polycrystalline powder with a narrow particle size distribution was obtained. The primary particle size of the obtained SrBi 2Ta 2O 9 powder was around 40 nm. In comparison with the solid-state reaction, the newly developed colloid-gel process significantly reduces the heating temperature for synthesizing SrBi 2Ta 2O 9, as well as the particle size of the obtained powder.