MECHANISM OF TEMPERATURE-DEPENDENCE OF PIEZOELECTRIC PROPERTIES FOR PB(ZR,TI)O3

Temperature dependence of piezoelectric properties was measured for a tetragonal and a rhombohedral Pb(Zr, Ti)O3 (denoted as t-PZT and r-PZT , respectively). A least squares fitting of complex admittance data wa s employed in order to precisely determine various electromechanical c onstants. It was confirmed that the piezoelectric constant d31 of the t-PZT was thermally stable while that of the r-PZT largely increased w ith temperature. It was clarified that the elastic compliance s11E and the electromechanical coupling factor k31 decreased and the dielectri c constant epsilon33T increased with temperature in the t-PZT, giving rise to the thermally stable behavior of d31. In the case of the r-PZT , the increase in epsilon33T dominated the temperature dependence of t he d31. From the XRD analysis, it seemed that the increase in epsilon3 3T of the r-PZT originated from a large thermal expansion of the unit cell volume.