Calculation of quasi-static electromechanical coupling coefficients for electrostrictive ceramic materials

The quasi-static coupling coefficients, k/sub 13/ and k/sub 33/, for electrostrictive ceramics are computed analytically. The calculation is based on a three-dimensional constitutive relation that models both electrostriction and nonlinear dielectric behaviors. The results show that the coupling factors depend on the amplitudes of the applied ac field and the dc bias, as well as the mechanical prestress. For an actuator without bias voltage or prestress, the coupling coefficients approach an asymptotic value with increasing electric field. The primary coefficients, k/sub 13/ and k/sub 33/, for a lead magnesium niobate, Pb(Mg/sub 1/3/Nb/sub 2/3/)O/sub 3/-PbTiO/sub 3/BaTiO/sub 3/(PMN-PT-BT), based relaxor ferroelectric are computed as an example. The results show that the coupling coefficients for PMN-PT-BT materials are roughly comparable with those of existing piezoelectrics. These coefficients are important parameters for material section and power source design for transducer devices.<
>