Dielectric and electromechanical properties of (1-x)PMN-xPZT ferroelectricceramics

The dielectric and electromechanical characteristics of the (1 - x)PMN-xPZT ferroelectric ceramics have been obtained at different temperatures, ampli tudes, and frequencies of the measuring field and at different bias field s trengths. It is shown that this ferroelectric ceramics at low and infralow frequencies possesses pronounced relaxor properties in a certain temperatur e range and ferroelectric properties in other temperature range. The temper ature and amplitude ranges have been determined, in which the permittivity epsilon' either only decreases or first increases and then decreases with a n increase in the measuring field amplitude E-0. The temperature ranges of existing the phases similar to the superparaelectric phase, dipole glass ph ase, and ferroelectric phase are evaluated from the temperature dependences of the coercive field E-c(T) and the remanent polarization P-r(T) and also from the reverse dependences of epsilon* and the electromechanical charact eristics. The PZT concentration in the PMN-PZT system is determined, at whi ch the electrostrictive constant M-11 is maximum. It is demonstrated that, in the neighborhood of the temperature at a maximum of epsilon', the strain S-3 is quadratic in the field E-=; that is, S-3 = M11E2. (C) 2000 MAIK "Na uka/Interperiodica".