Temperature dependence of electrostriction in rhombohedral Pb(Zn1/3Nb2/3)O3–PbTiO3 single crystals

The temperature dependent electrostrictive behavior of rhombohedral Pb(Zn1/3Nb2/3)O3-xPbTiO3 crystals (PZN-PT, x<0.09) was investigated. Although the application of an E field induces a macroscopic ferroelectric phase at room temperature, rhombohedral crystals still exhibit relaxor characteristics, such as polarization modulation. The polarization is believed to become homogeneous in association with the E-field induced phase transition into the tetragonal phase. Electrostrictive coefficients, Q11∼9.5×10−2 m4/C2 and Q12∼−3.6 m4/C2 were calculated at the high fields. Strain values calculated based upon these coefficients were found to be significantly greater than that measured at low fields, being attributed to polarization modulation. With decreasing temperature, the theoretical strain values came closer to measured strain values. Theoretical and calculated values are expected to be equal at temperatures lower than 150 K, where the polarization in the E-field exposed crystal is homogeneous and collinear.