PHASE-TRANSITIONS IN ALKYLAMMONIUM HALOGENOANTIMONATES AND BISMUTHATES

A review of the results of studies on the structure, phase transitions and physical properties of alkylammonium halogenoantimonates (III) and bismuthates (III) is presented. The crystals of these compounds are characterized by a variety of anionic structures and show a number of phase transitions including those to polar phases. We concentrate here mainly on dielectric and pyroelectric properties, spontaneous polarization and DSC studies. The mechanism of the phase transitions is discussed based on the results of X-ray, dielectric relaxation, PMR, IR and R spectra studies gathered so far. A particular role is played by a reorientational motion of the alkylammonium cations. © 1990, Taylor & Francis Group, LLC. All rights reserved.