Piezoelectricity and aging effects in the PMN-PT system

PMN ceramics present piezoelectricity under an applied de bias field. The r elative dielectric permittivity varies, in general, over a wide range of va lues of the applied de electric field. The purpose of this work is to study the induced piezoelectricity effect produced by an applied de electric fie ld in the 2.7PMN-0.1PT system assuming that the relative dielectric permitt ivity is a function of the applied de electric field. An expression to calc ulate the electrostrictive coefficient Q(31) by measuring the coupling fact or kp and the dielectric permittivity as functions of the applied electric field is presented. We have also studied the aging effects at different de electric fields, at room temperature, The experimental results reveal a cha nge in the aging rate for different electric fields.