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

The dielectric and electromechanical characteristics of the (1 - x)PMN-xPZT ferroelectric ceramics have been obtained at different temperatures, amplitudes, and frequencies of the measuring field and at different bias field strengths. It is shown that this ferroelectric ceramics at low and infralow frequencies possesses pronounced relaxor properties in a certain temperature range and ferroelectric properties in other temperature range. The temperature and amplitude ranges have been determined, in which the permittivity epsilon' either only decreases or first increases and then decreases with an increase in the measuring field amplitude E-0. The temperature ranges of existing the phases similar to the superparaelectric phase, dipole glass phase, 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 characteristics. The PZT concentration in the PMN-PZT system is determined, at which 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 "Nauka/Interperiodica".