Microwave synthesis and sintering of Ba(Mg1/3Ta2/3)O-3

Ba(Mg1/3Ta2/3)O-3, BMT, was synthesized and sintered by microwave processing at 2.45 GHz. Appropriate amounts of BaCO3, MgO, and non-stoichiometric Ta2O5-x were used as starting materials for the synthesis. BMT was obtained by heating the precursors in a multimode microwave cavity of 2 kW between 900 degrees C and 1300 degrees C for just 20 min. The synthesis was carried out in N-2 atmosphere to prevent the oxidation of Ta2O5-x. The perovskite BMT starts forming at 900 degrees C and becomes single phase material at 1300 degrees C. The sintering of BMT was carried out in a single mode microwave cavity for 5 to 30 min at 1400 degrees C to 1600 degrees C without using any sintering aid. A relative density of 97% was obtained in 30 min of microwave sintering at 1600 degrees C. In contrast, it was found that to achieve the same densification, it requires 6 h of soaking at the same temperature in conventional sintering process. (C) 2000 Elsevier Science B.V. All rights reserved.