Formation and characterization of lead magnesium niobate synthesized from the molten salt of potassium chlorate

Abstract

Lead magnesium niobate powders were prepared by reacting PbO, MgO and Nb2O5 in the molten salt of potassium chlorate. The formation of a single phase perovskite PMN requires a combination of 100 mol % excess lead oxide and a reaction temperature of 900°C. The average particle size of resulting PMN powders increases with increasing reaction temperature and the amount of excess lead oxide added, while the particles undergo a change from a round to a cubical morphology. Too much excess PbO (> 100 mol %) in the starting composition promoted grain growth in the molten salt-derived PMN ceramics, although the sintered density is not much affected at 1200°C and above. It also degrades the dielectric properties of sintered PMN, as a result of the occurrence of PbO-rich precipitates at the grain boundaries and grain junctions. © 1998 Elsevier Science S.A.