Study of the structure and dielectric relaxation behavior of Pb(Ni1/3Nb2/3)–PbTiO3 ferroelectric ceramics

Relaxor-type ferroelectric ceramics, (1−x)Pb(Ni1/3Nb2/3)O3–xPbTiO3 (x=0.28–0.42) were synthesized by the columbite precursor method. The phase structure and dielectric properties were investigated. X-ray diffraction results demonstrate that a region with both pseudocubic and tetragonal phase in existence lies in the composition range x=0.34–0.38, which is the morphotropic phase boundary (MPB). Examination of the dielectric behavior indicates that the ceramics exhibit abnormal high dielectric constant near the MPB composition. In addition, the transformation of (1−x)PNN–xPT from relaxor to normal ferroelectric behavior with the PT content increasing is successive.