Dielectric relaxation in pseudo-one-dimensional ferroelectric CsD2PO4

Abstract

Dielectric dispersion in pseudo-one-dimensional hydrogen-bonded ferroelectric Cs${\mathrm{D}}_{2}$P${\mathrm{O}}_{4}$ was measured in the frequency range from 100 kHz to 2 GHz for temperatures between -13 and 30\ifmmode^\circ\else\textdegree\fi{}C. The observed relaxation is monodispersive in the paraelectric phase, except in the vicinity of the transition. The static dielectric constant ${\ensuremath{\epsilon}}_{s}$ shows classical critical behavior, with the critical coefficient $\ensuremath{\gamma}=1$. The relaxation frequency ${f}_{\ensuremath{\epsilon}}$ is much lower than in corresponding three-dimensional systems and exhibits a pronounced critical slowing down with a nonclassical exponent of 1.3. Outside the critical region in the paraelectric phase, $\ensuremath{\epsilon}$ and ${f}_{\ensuremath{\epsilon}}$ can be described reasonably well by a pseudo-one-dimensional Ising model, treating the interchain interactions in the mean-field approximation. The intrachain and interchain interactions obtained agree well with previously determined values. The noninteracting deuteron intrabond-jump time is much smaller than in K${\mathrm{D}}_{2}$P${\mathrm{O}}_{4}$ but has the same activation energy.