Phase Energy Determined from Stress and Electric-Field-Induced Phase Transformations in [011]C Cut 0.24PIN-PMN-PT Single Crystals

The effect of composition and temperature on the large field behavior of [011]C cut and poled (d32-mode) rhombohedral relaxor ferroelectric 0.24PIN-(1−x)PMN-xPT single crystals was characterized under electromechanical loading and the relative phase energy determined. The electric field and stress induced polarization and strain response and field dependent material properties are reported for two concentrations of lead titanate (PT), with one PT concentration closer to the morphotropic phase boundary, at low and high temperature. A thermodynamic analysis to determine the relative energy levels of the rhombohedral and orthorhombic phases is based on the path integration of the measured data to determine external work done to drive the phase transition. The effect of heat generated by irreversible strain and electric displacement increments (hysteresis in the phase transformation) was removed from the work done during the loading cycle and the relative Helmholtz free energy density levels of the phases was determined