Effect of hydrostatic pressure and longitudinal electric field on phase transitions and thermodynamic characteristics of quasione-dimensional CsH$_2$PO$_4$ ferroelectric

TL;DR

This study models how hydrostatic pressure and electric fields influence phase transitions and thermodynamic properties of CsH₂PO₄ ferroelectric, revealing pressure-induced antiferroelectric phases and electric field effects on phase transition behavior.

Contribution

A two-sublattice proton ordering model incorporating lattice strains and dipole moment dependence, providing new insights into phase behavior under external pressures and fields.

Findings

Pressure induces antiferroelectric phase transition.

Electric field suppresses the paraelectric-ferroelectric transition.

Model explains smearing of phase transition and phase suppression.

Abstract

We propose a two-sublattice proton ordering model for the quasione-dimensional CsH$_2$PO$_4$ ferroelectric with hydrogen bonds, which takes into account linear on lattice strains $u_1$, $u_2$, $u_3$ and $u_5$ contribution to the energy of proton subsystem. The model also takes into account the dependence of effective dipole moments of pseudospins on the order parameters, which enables one to agree the effective dipole moments in paraelectric and ferroelectric phases. Within this model in two-particle cluster approximation on short-range interactions and in the mean field approximation on long-range interactions, there is investigated the behaviour of spontaneous polarization, longitudinal dielectric permittivity and molar heat capacity under the action of hydrostatic pressure and longitudinal electric field. The phase transition into antiferroelectric phase under high pressures is explained. The character of smearing of the paraelectric-ferroelectric phase transition as well as suppression of the antiferroelectric phase at the presence of electric field is studied.