High-pressure studies of dielectric relaxation in ferroelectric pyridiniumtetrafluoroborate crystals

Dielectric relaxation of ferroelectric pyridinium tetrafluoroborate single crystal was measured as a function of hydrostatic pressure and temperature. High-pressure caused a shift the ferroelectric-paraelectric phase transiti on at T-1=238.7 K as well as the non-ferrolectric phase transition at T-2=2 04 K towards higher temperatures. The influence of pressure on the critical slowing down process at the ferroelectric-paraelectric phase transition wa s analyzed. Moreover. in the low temperature phase (below 204 K) a relaxati on process. characterized by an enthalpy of 13.2 kJ/mole, was observed. nle activation enthalpy of the process was found to increase linearly with pro cess.