Preparation and characterization of nanocrystalline Sr1-xBi2+yTa2O9 powders

Nanocrystalline powders of stoichiometric and non-stoichiometric (i.e. strontium deficient) strontium bismuth tantalate (SBT; Sri(1-x)Bi(2+y)Ta(2)O(9) with x = 0, 0.1, 0.2, 0.3 and 0.4) compositions has been prepared starting from an aqueous precursor solution that is constituted of tartarate salt of tantalum, strontium salt of ethylenediaminetetraacetic acid (EDTA) and triethanolamine (TEA) complex of bismuth. Complete dehydration of the precursor solution generates a fluffy, mesoporous, carbonaceous precursor mass, which on direct calcination at 700-750 degreesC/2 h results in phase-pure Sr1-xBi2+yTa2O9 powders, with average particle size ranging between 23 and 33 nm. The phase transition temperatures (T.) of these ceramic compositions have been measured and have been observed to increase with depleting Sr-content. The dielectric constant (e) of the sintered (at 900 degreesC/4 h) pellets of the Sri(1-x)Bi(2)Ta(2)O(9) compositions, have been measured (at 1 kHz) at their respective phase transition temperatures (T-c) and the values have been compared with those reported through other methods. (C) 2003 Elsevier Science B.V. All rights reserved.