Hydrostatic pressure dependence of the relaxational mode of KH₂PO₄ studied by light scattering

Abstract

The light scattering spectra of the x(yx)y geometry in KH₂PO₄ were measured by a tandem Fabry-Perot interferometer as functions of both pressure and temperature. From the recorded spectra, the relaxation time of the ferroelectric mode was deduced and was analyzed on the basis of the Curie-Weiss law at several pressures. The relaxation time of individual dipoles (τ₀) was found as a function of pressure. The value of τ₀ at 1 bar (1.57 × 10^–13 s) decreases almost linearly to 0.57 × 10^–13 s at 4.17 kbar. A tentative calculation of the protonic relaxation time using a compressible double Morse potential was performed. The result was compared with the relaxation time of the ferroelectric mode.