Nonlinear stress-strain behavior and stress-induced phase transitions in soft Pb(Zr1-xTix)O3 at the morphotropic phase boundary

Temperature-dependent stress-strain behavior of various soft Pb0.98Ba0.01(Zr1-x Ti-x)(0.98)Nb0.02O3, 0.40 <= x <= 0.60, compositions was characterized between 25 and 400 degrees C to determine the influence of crystal structure on ferroelasticity. The ferroelastic response was found to depend significantly on the crystal phase as well as the spontaneous strain, both of which varied with temperature. The remanent strain for rhombohedral materials was shown to be above the theoretical maximum allowed by the crystal spontaneous strain. This observed behavior indicates the presence of hysteretic processes in addition to ferroelasticity during mechanical compression. A phenomenological free energy analysis was used to predict the effects of stress on the stable phase in ferroelectrics and indicates the susceptibility of the rhombohedral and tetragonal structure to a stress-induced phase transition. Modeling results indicate the relative importance of such phase transitions on macroscopic stress-strain behavior, giving an indirect method to observe field-induced phase transitions in polycrystalline ferroelectrics. DOI: 10.1103/PhysRevB.87.094116