Nanocrystalline W-doped SrBi 2Ta 2O 9 of layered perovskite structure derived from mechanical activation

Abstract

To study the effects of doping the layered perovskite SrBi 2Ta 2O 9 with an appropriate amount of tungsten, both undoped and W-doped SrBi 2Ta 2O 9 (SBT) of nanocrystallinity were synthesized by mechanical activation of constituent oxides of strontium oxide, bismuth oxide, tantalum oxide and tungsten oxide at room temperature. A nanocrystalline single perovskite phase was observed in SrBi 2(Ta 1-xW x) 2O 9 with up to x=0.1. SrBi 2(Ta 0.9W 0.1)O 9 shows a higher Curie temperature than that of undoped SBT, although it exhibits a very similar layered perovskite structure. The ferroelectric and impedance behaviors of SrBi 2(Ta 0.9W 0.1) 2O 9 were studied over a range of test temperatures and frequencies, in order to understand the effects of W-doping in SBT, given that W exhibits a similar ionic size to Ta but with a variable valence.