Microstructural Inhomogeneity in Sintered Pb(Mg1/3Nb2/3)O3-PbTiO3 Based Dielectrics

The sintering behavior and microstructural development of dielectric ceramics based on Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ solid solutions are greatly affected by the formation of a liquid phase at ∼ 1290°C. Prolonged sintering at and above this temperature gives rise to an excessive PbO loss and the resultant variation in composition leads to an inhomogeneous microstructure. The inhomogeneity is characterized by the formation of a dense, localized region containing a PbO-rich liquid near the surface with a porous interior region in the bulk of the sample.