Dielectric properties anomaly of (1-x)Pb(Ni_1/3Nb_2/3)O_3-xPbTiO_3 ceramics near the morphotropic phase boundary

摘要

Dielectric properties and the phase compositions of (1-x)Pb(Ni_1/3Nb_2/3)O_3-xPbTiO_3 ceramics were investigated. A morphotropic phase boundary (MPB) in the system between pseudocubic and tetragonal phase regions has been identified to lie in the composition range x = 0.34-0.38 by means of x-ray diffraction and dielectric measurements. The samples of composition lying near the MPB have good dielectric properties, but at the same time, exhibit two dielectric peaks. The possible reasons for the occurrence of dielectric bipeaks are discussed. One dielectric peak is phase transition peak, and the other peak lying in 130-150 deg C temperature range is suggested to result from structure defects in the ceramics.