Composition dependence of field induced phase transformations in [0 1 1]C PIN–PMN–PT relaxor ferroelectric single crystals with d322 piezoelectric mode

Abstract

Relaxor ferroelectric single crystals are used in sonar, medical ultrasound, accelerometers and energy-harvesting applications due to their large electromechanical coupling. In this work, the compositional dependence of the electromechanical properties of [011]C cut relaxor ferroelectric lead indium niobate–lead magnesium niobate–lead titanate single crystals, xPb(In1/2Nb1/2)O3–(1-x-y)Pb(Mg1/3Nb2/3)O3–yPbTiO3 (PIN–PMN–PT) was determined. The effect of increasing the concentration of lead indium niobate (xPIN) and increasing the concentration of lead titanate (yPT) on compositions near the morphotropic phase boundary was explored. Specimens were subjected to combined electrical, mechanical and thermal loading. The electric field induced changes of polarization and strain were measured at a series of preload stresses and the stress induced polarization and strain changes were measured at a series of bias electric fields. This was repeated at several temperatures. Evidence of a phase transformation from ferroelectric rhombohedral to ferroelectric orthorhombic was observed in the form of jumps in strain and electric displacement at critical field levels. The linear piezoelectric constant, dielectric permittivity, elastic compliance, thermal expansion, pyroelectric coefficient and rate of change of the material properties with temperature were determined including a scalar measure of electromechanical work indicating the start of the field induced phase transformation.