Dielectric anomalies in boracites

Abstract

Abstract Experimental results are reported on the dielectric behavior of Fe3B7O13I, Ni3B7O13Br, Cu3B7O13CI, and Mn3B7O13I, near their cubic-orthorhombic phase transition. Fe3B7O13I and Ni3B7O13Br show the typical dielectric behavior of boracites, whereas Cu3B7O13CI and Mn3B7O13I exhibit a different dielectric anomaly. Both types of behavior can be discussed on the basis of a Landau expansion of the thermodynamic potential.