Development of perovskite structure and electrical properties of Pb(Zr1/2Ti1/2)O3-Pb(Ni1/3Nb2/3)O3 system

Phase pure perovskite structure (1 - x) Pb(Zr1/2Ti1/2)O-3-xPb(Ni1/3Nb2/3)O-3 (PZT-PNN, x = 0.05 - 0.40) ferroelectric ceramics were prepared by conventional solid-state reaction method via the columbite precursor technique. The PZT-PNN ceramics sintered at 1225 degrees C for 2 h exhibit rather homogenous microstructure and high relative density. With the increase of the Pb(Ni1/3Nb2/3)O-3 (PNN) content, the crystal structure of PZT-PNN changes gradually from tetragonal perovskite structure to rhombohedral one, where the morphotropic phase boundary (MPB) composition locates at a region of x = 0.15 - 0.20 determined by X-ray diffraction (XRD) and dielectric measurements. Furthermore, the dielectric response peaks of PZT-PNN also changes from narrow, sharp and almost frequency independent peaks of normal ferroelectrics to broad, diffused and apparent frequency dependent peaks of relaxor ferroelectrics, accompanied by the decrease of the temperature of dielectric maximum (T-m) with the increase of the PNN content. PZT-PNN with the MPB composition exhibits integral excellent electrical properties, where 0.80PZT-0.20PNN exhibits the maximum value of dielectric constant epsilon(m) 26750 at 280.6 degrees C, the remanent polarization P-r is 25.17 mu C/cm(2), coercive field E-c is 5.82 kV/cm, and piezoelectric constant d(33) reaches 281 pC/N.