SPONTANEOUS POLARIZATION BEHAVIOR IN FERROELECTRICS

The spontaneous polarization behaviour in the vicinity of the ferro-pa raelectric phase transition is discussed. The experimental results for ferroelectrics are analyzed in the case of pyroelectric function inve stigations. The description in terms of the two-point scaling hypothes is is then applied in order to explain the tail of the polarization in the paraelectric phase. The critical exponents are evaluated. The Cur ie temperature determined from experimental data above or below the te mperature for the maximum of the pyroelectric function is considered i n the model assuming that the fixed point can be related to one of the stability points for the ferro- or paraelectric phase, respectively. In the model presented the temperature hysteresis seems to be a natura l phenomenon because of the phase transition point whose position resu lts from the competition between fluctuations in the ferro-paraelectri c phase coexistence interval.