Structural phase transformation and electrical properties of (0.90-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3-0.10Pb(Fe1/2Nb1/2)O3 ferroelectric ceramics near the morphotropic phase boundary

Novel solid solutions of (0.90 - x)Pb(Mg1/3Nb2/3)O-3-PbTiO3-0.10Pb(Fe1/2Nb1/2)O-3, where x = 0.29, 0.31, 0.33 and 0.35, were investigated from the viewpoint of structural phase transformation, dielectric, ferroelectric and piezoelectric properties. X-ray diffraction and Raman scattering measurements demonstrated that their phase structures experienced a gradual transition process from rhombohedral to tetragonal phase near the morphotropic phase boundary (MPB) region with increasing PbTiO3 content (x). Corresponding to the structural phase transition near the MPB, large dielectric constants (epsilon(r)) were obtained at the compositions of x = 0.31 (F, = 3094 at I kHz) and x = 0.33 (epsilon(r) = 2927 at 1 kHz). The maximum remnant polarization (P-r = 26.5 mu C cm(-2)) was obtained at the composition x = 0.31, and the electromechanical factor (k(p) = 0.59) and piezoelectric coefficient (d(33) = 545 pC N-1) were also maximized at this composition, which indicated the enhanced electrical properties near the MPB. (c) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.