High electric-field-induced strain of Pb(Mg1/3Nb2/3)O3-PbTiO3 crystals and their application in multilayer actuators

Electric-field-induced strain behavior of differently oriented and componential (1-x)Pb(Mg1/3Nb2/3)O3xPbTiO3 (PMNT) crystals was investigated. An optimum composition range (29%≤x≤31%) of left angle 001 right angle -oriented PMNT crystals was ascertained for multilayer actuator applications, which exhibited high-strain and low-hysteresis behavior. The rhombohedral (monoclinic)-tetragonal phase-transition behavior in PMNT single crystals is dependent on their thermal and electric history, which markedly impacts on the strain performance of the crystals. In contrast to PZT-SF (doped PZT ceramics) multilayer actuators, the strain values for 20-layer PMNT actuators with individual element sizes of 6 x 6 x 0.3 mm3 are larger by more than five times at 20 kV/cm (0.373% compared to 0.072%), and 23-μm displacements can been achieved. Against 40-N load, the displacements are decreased to 20.2 μm. (orig.)