Transmission electron microscopy of second-phase particles in Pb(Sc1/2Ta1/2)O3 Ferroelectric ceramics

Pb-rich second-phase particles in perovskite-structured Pb(Sc_1/2Ta_1/2)O₃ (PST) ferroelectric ceramic relaxors have been investigated using transmission electron microscopy. The second-phase particles were observed to exhibit a range of morphologies which included spheroidal inclusions, plate-like precipitates and intergranular films. Moiré fringes and lattice images have been used to identify various non-perovskite phases. It is deduced that excess PbO, which is used to assist densification through liquid phase sintering and to promote grain growth, becomes entrapped within the ceramics, thereby producing Pb-enriched phases that have adverse effects on dielectric properties.