Enhancing piezoelectric properties of high-Curie temperature PMN-PH-PT piezoelectric ceramics by citrate method

The high-Curie temperature (T-C) 0.15Pb(Mg1/3Nb2/ 3)O-3-0.38PbHfO(3)-0.47PbTiO(3) (PMN-PH-PT) piezoelectric ceramics were prepared via the citrate method. The rather homogeneous microstructure with nm-scale particles of the PMN-PH-PT precursor powders were attained with a calcining temperature ranging from 650 degrees C to 800 degrees C and pure perovskite structure of the PMN-PH-PT ceramics were prepared by the citrate method sintered from 1225 degrees C to 1265 degrees C. The content of the rhombohedral phase in the PMN-PH-PT ceramics sintered at 1245 degrees C increases first and then decreases with elevating the calcining temperature, and all the synthesized PMN-PH-PT ceramics have high density. The PMN-PH-PT ceramics exhibit complex dielectric behavior, in which the PMN-PH-PT ceramics calcined at 800 degrees C and sintered at 1245 degrees C exhibit the best dielectric properties with epsilon(m) = 26269 and T-C/T-m = 297 degrees C. The nonlinear dielectric behavior of the PMN-PH-PT ceramics was successfully studied by the Rayleigh relation, which also reveals a polymorphic phase transition (PPT) resulted from the polar nanoregions (PNRs) in the PMN-PH-PT ferroelectric ceramics. Due to the mutual influences of grain size, domain configuration and microstructure morphology, the electrical properties of the synthesized PMN-PH-PT ceramics are influenced greatly, in which the PMN-PH-PT ceramics calcined at 775 degrees C and sintered 1245 degrees C exhibit the optimum ferroelectric and piezoelectric properties. The piezoelectricity of the PMN-PH-PT ceramics is superior to the same compositional ceramics synthesized by the columbite precursor method, which can be attributed to the morphotropic phase boundary (MPB) effect and densified microstructure induced by the wet-chemical citrate method. The PMN-PH-PT ceramics prepared by the citrate method exhibit excellent thermal stability of the piezoelectric and ferroelectric properties surpassing the common usage temperatures, indicating their promising transducer applications under elevated environmental temperatures. (C) 2017 Elsevier B.V. All rights reserved.