Theory of Rochelle salt: beyond the Mitsui model

TL;DR

This paper introduces a generalized four-sublattice model for Rochelle salt, extending the Mitsui model to better describe its phase transitions and dielectric properties, including effects of transverse electric fields.

Contribution

It develops a new four-sublattice order-disorder model that incorporates symmetry and dipole orientations, advancing the understanding of Rochelle salt's phase behavior beyond previous models.

Findings

The model predicts temperature and field dependence of dielectric susceptibility.

Transverse electric field influences phase transition points and polarization.

Enhanced agreement with experimental data on Rochelle salt properties.

Abstract

A simple four-sublattice order-disorder model is developed for description of phase transitions and dielectric properties of the Rochelle salt crystal. The model is developed as a generalization of the semimicroscopic Mitsui model. The symmetry properties of lattice and spatial orientations of effective dipoles connected with the asymmetric structure units in the elementary cell are taken into account. The model allows to investigate the temperature and field behaviour of transverse (besides longitudinal) components of dielectric susceptibility. The influence of the transverse electric field $\vec{E}\parallel\vec{b}$ on the phase transition points and spontaneous polarization is studied.