Synthesis of Pb(Mg1/3Nb2/3)O3 in Excess Lead Oxide by Mechanical Activation

Abstract

Twenty hours of mechanical activation of mixed oxides at room temperature led to the formation of Pb(Mg1/3Nb2/3)O3 (PMN) in excess PbO. The crystallinity of the activation-derived perovskite PMN phase was further established when the activated PMN-PbO phase mixture was subjected to calcination at 800°C. Pyrochlores, such as Pb3Nb4O13 and Pb2Nb2O7, were not observed as transitional phases on mechanical activation and subsequent calcination, although 50% excess PbO was deliberately added. The perovskite PMN phase was recovered by washing off excess PbO using acetic acid solution at room temperature. It was sintered to a relative density of 98.9% of theoretical at 1200°C for 1 h and the sintered PMN exhibited a dielectric constant of ∼14 000 at 100 Hz and a Curie temperature of -11°C.