Investigation of electromechanical properties of 0.68 Pb(Mg _1/3Nb_2/3 )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(Mg 1/3 Nb 2/3 )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 90 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.