Effect of Mn-doping on the structure and electric properties of 0.64Pb(In0.5Nb0.5)O3-0.36PbTiO3 ceramics

Abstract

In order to study the effect of defect dipoles on relaxor-based ferroelectrics, 0.64Pb(In0.5Nb0.5)O3-0.36Pb(Ti1−xMnx)O3 (x=0−0.15) ferroelectric ceramics were synthesized using the two-step solid state reaction method. The phase structure, ferroelectric, piezoelectric and dielectric properties were investigated. Upon increasing the Mn content, the phase of the ceramics transforms from tetragonal to rhombohedral symmetry, the magnitude of remnant polarization and piezoelectric coefficient decreasing because of the hardening effect of the defect dipoles and the variation of composition. The coercive field, however, decreases from 22kV/cm to 12.5kV/cm with x≤0.04 initially owing to a phase transition, and then increasing since the defect dipoles provided a driving and stabilizing force for domain stability. The stabilizing force also resulted in constricted hysteresis loops for samples with composition of x≥0.04 after aging. The temperature dependence of dielectric properties showed that the Curie temperature decreased from 312°C (x=0) to 237°C (x=0.15), and the degree of relaxor behavior was enhanced with increase of Mn content. It indicates that the defect dipoles, confirmed by the existence of oxygen vacancies, play an important role in the electrical properties of Mn-doping PIN-PT ceramics.