Processing and Characterization of Microemulsion‐Derived Lead Magnesium Niobate

Lead magnesium niobate, Pb(Mg 1/3 Nb 2/3 )O 3 (PMN), with 3 wt% excess PbO content has been successfully prepared via a microemulsion processing technique. By stepwise hydrolysis using aqueous ammonia as the precipitant, hydroxide precursor was obtained from nitrate solutions dispersed in the nanosized aqueous domains of a microemulsion consisting of cyclohexane, mixed poly(oxyethylene) 5 nonyl phenol ether (NP5) and poly(oxyethylene) 9 nonyl phenol ether (NP9), and an aqueous phase. Upon calcination of the microemulsion‐derived precursor at 780°C, an ultrafine perovskite PMN powder with less than 5% pyrochlore phase was obtained. The percentage of perovskite phase increases with increasing calcination temperature, reaching ∼98% at 900°C. The resulting PMN powder exhibits a near‐spherical particle morphology although particle agglomerates of ∼0.3 µm in average diameter occur when they are calcined at 850°C. When sintered at 1150°C, the microemulsion‐derived PMN showed a maximum relative density of ∼95.6% theoretical density, which gives a maximum dielectric constant of ∼11 000 at 1 kHz and a Curie temperature of ‐6°C.