Kinetic effects inducing metastable intermediate phase in PbK2LiNb5O15 single crystal
Résumé
The kinetic effects accompanying an unusual ferroelectric-paraelectric phase transition is analyzed in the PbK2LiNb5O15 single crystal. The ferroelectric-paraelectric phase transition takes place at Curie temperature (TC) of 639 K, being strongly influenced by the heating/cooling rate (υ). The phase transition occurs through metastable intermediate phases spanning a 40 K interval. These kinetic effects and relaxation phenomena are highlighted around the phase transition region. The dielectric measurements, which have been performed at 500 kHz considering different temperature rates, on heating and cooling, have shown not only the variation of TC as a function of υ, but also, the widening of the dielectric thermal hysteresis as a function of υ.