Simultaneous synthesis and sintering of lead magnesium niobate ferroelectric ceramics

Lead magnesium niobate (Pb(Mg1/3Nb2/3)O3) ceramics have been synthesized and sintered simultaneously by a newly developed reaction sintering process. During the formation of pyrochlore phase, the specimens expand at first. When Pb(Mg1/3Nb2/3)O3 begins to form at elevated temperatures, the specimens rapidly shrink, indicating the occurrence of reaction sintering. After sintering at 1000°C, monophasic perovskite Pb(Mg1/3Nb2/3)O3 ceramics with high sintering density (>96%) are obtained. Adding 5 mol% excess MgO further enhances the densification of Pb(Mg1/3Nb2/3)O3. However, when 20 mol% excess MgO is added, MgO particles distribute on the grain boundary of Pb(Mg1/3Nb2/3)O3, thereby impeding the densification process. The 5 mol% MgO-added Pb(Mg1/3Nb2/3)O3 ceramics exhibit high density as well as high dielectric permittivity.