Experimental results are reported on the dielectric behavior of Fe3B7O13l, Ni3B7O13Br. Cu3B7O13Cl, and Mn3B7O13I, near their cubic-orthorhombic phase transition. Fe3B7O13l and Ni3B7O13Br show the typical dielectric behavior of boracites, whereas Cu3B7O13Cl, 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.
Bibliographical noteFunding Information:
This work was supported by the Defense Advanced Research Projects Agency, and monitored by the U.S. Army Night Vision and Electro-Optics Laboratories, Fort Belvoir, Virginia.
Partial support of this work by the "Fonds National Suisse pour la Recherche Scientifique" is gratefully acknowledged.