Dielectric properties of chemically synthesized PLZT and PZT: diffused phase transition and effect of lead non-stoichiometry

Dielectric and ferroelectric properties of chemically synthesized and sintered lead lanthanum zirconate titanate and lead zirconate titanate discs were studied. The as-burnt powders were directly sintered to 94% and 96% of the theoretical density at 1100 degrees C and 1200 degrees C, respectively for lead lanthanumm zirconate titanate (PLZT) and 96.7% at 1100 degrees C for lead zirconate titanate (PZT). The sintered PLZT samples showed improved dielectric properties whereas PZT showed improved ferroelectric properties compared with the data reported in the literature. Dielectric permittivity at room temperature of the 1100 degrees C sintered PLZT sample with grain sizes 0.4-1.2 mu m was similar to 5000, at all measured frequencies. Evaporation of PbO from the sample generated micro inhomogeneity, which was detrimental for the dielectric property. A sintered PLZT sample underwent a completely diffused phase transition whereas a sintered PZT sample underwent a partially diffused phase transition. The measured values of remnant polarization of the 1100 degrees C sintered PZT and PLZT samples were 54.0 and 40.0 mu C cm(-2), respectively. The coercive fields observed for these samples were 13.3 and 7.7 kV cm(-1), respectively.