Influence of compressive stress and electric field on the stability of [011] poled and [0(1)over-bar1] oriented 31-mode PZN-0.055PT single crystals

The effect of compressive stress, in the presence of an electrical field along the [011] direction, on the phase transition stability of [0 (1) over bar1] oriented and [011] poled relaxor (1 - x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-PT) single crystals in the transverse length extensional 31-mode geometry is investigated. The thermal, electrical, and mechanical stability range for operation lacking elastic instabilities is identified and compared with conventional 33 and 32-mode geometries with the near morphotropic composition of x similar to 0.055. It is found that the 31-mode geometry retains the stable, room temperature ferroelectric rhombohedral (R) symmetry up to and exceeding compressive stresses, along the [0 (1) over bar1] direction, of 90 MPa under zero field conditions. Under zero stress conditions, a phase transformation from the stable rhombohedral symmetry to the low symmetry ferroelectric orthorhombic (O) phase occurs in the presence of an electric field of 0.85 MV/m. Stabilization of the R-O phase transformation against electric field drive occurs as a function of compressive prestress, similar to the 33-mode geometry. And, under sufficiently large compressive stress, an R-T (or R-M-A-T) transformation is identified and discussed.