Investigation of electromechanical properties of 0.68 Pb(Mg1/3Nb2/3)O3-0.32 PbTiO3 single crystals under uniaxial and hydrostatic pressures

This paper reports the uniaxial and hydrostatic pressure dependence of the electromechanical property of the 0.68 Pb(Mg1/3Nb2/3)O-3-0.32PbTiO(3) (PMNT), single crystals. A significant decrease was observed in the mechanical quality factor (Q(m)) under both uniaxial and hydrostatic pressures. This decrease was most dramatic under uniaxial conditions. The decrement in the magnitude of the Q(m) with pressure can be attributed to the stress induced transformation into ferroelectric tetragonal state whose c-axis is oriented at 90degrees from the direction of the applied stress and increased polar fluctuations within the poled piezoelectric state. The low value of Q(m) under uniaxial conditions may present a significant thermal stability problem under moderate drive levels.