Fabrication And Properties Of XPb(Ni_1/3Nb_2/3)O₃-（1-x）Pb(Hf_0.45Ti_0.55)O₃Ceramics

Pb(Ni_1/3Nb_2/3)O₃（PNN） is a kind of relaxor ferroelectric with perovskitestructure, the Curie temperature of PNN is about-120oC. Pb（ZrxTi1-x）O3（PZT） isnormal ferroelectric, it’s Curie temperature is about390oC. The normal ferroelectricand relaxor ferroelectric can be connected together to form solid solution. Thesesolid solutions have high dielectric constant and lower sintering temperature. ThePNN and the PZT with the composition close to the MPB can form the binarysystems PNN-PZT. The Curie temperature in PNN-PZT system can be engineered ina wide range of temperature by changing the amount of PZT in the system. ThePNN-PZT with the composition close to the MPB yields high dielectricpermittivities, excellent piezoelectric coefficients and high pyroelectric coefficients.Pb（HfxTi（1-x））O3（PHT） is similar to the Pb(Zr_xTi_（1-x）)O₃, the material such asPNN-PZT and PNN-PHT are important candidate materials to fabricationmulti-layer ceramics capacitor and piezoelectric components.In this paper, we had chosen the binary system ceramics xPb(Ni_1/3Nb_2/3)O₃-（1-x）Pb（Hf0.45Ti0.55）O3. The powders of xPNN-（1-x）PHT were synthesized（x=0.1-0.8） by the columbite precursor method. After preparation, the perovskitephase formation and crystal structure of xPNN-（1-x）PHT ceramics were examinedby X-ray diffraction and Raman scatting at room temperature, the results indicatedthat the morphotropic phase boundary of xPNN-（1-x）PHT solid solution systemceramics was the composition of x=0.2. The rhombohedral and tetragonal phaseconexistenced in the0.2PNN-0.8PHT ceramic.After the confirm of the morphotropic phase boundary, we have measured theelectrical properties of the ceramics with composition close to the MPB （x=0.1-0.4）.Such as ferroelectric properties, piezoelectric properties, and dielectric properties.After the comparation and analysis of the results, we found that the0.2PNN-0.8PHTceramic sintering under the temperature1150oC displayed the best electricalproperties, with Curie temperature Tc, piezoelectric coefficient d33, dielectricpermittivity, electromechanical coupling kpbeing on the order of29.5μC/cm2,420pC/N, and49%, respectively.