BEHAVIOR OF A POLAR RELAXATION MODE AROUND THE PHASE-TRANSITION POINTIN THE ANTIFERROELECTRIC PBZRO3 SINGLE-CRYSTAL

In measurements of the dielectric dispersion carried out on single cry stals of antiferroelectric lead zirconate (PbZrO3) a polar relaxation mode in the frequency range from 10(6) to 10(9) Hz has been found. Usi ng the Cole-Cole relation for the complex epsilon(omega) response the relaxation frequency and dielectric step of the mode have been determi ned as functions of temperature. In the paraelectric phase the squared relaxation frequency well obeys a relation f(r)(2) similar to (T - T- 0) with T-0 = 222.9 degrees C. The temperature dependence of the diele ctric step corresponds to a sharp anomaly of the dielectric permittivi ty observed at the phase transition between the paraelectric and antif erroelectric states in PbZrO3. The phase transition mechanism of order -disorder type is discussed considering a disorder of the Pb sublattic e in the paraelectric phase. It should be pointed out that similar dip olar relaxation in ABO(3) perovskites is known to appear only in those with ferroelectric properties.