Comments on the dielectric relaxation in doubly doped CaF2

Abstract

Audio frequency dielectric-relaxation measurements have been recently used by Andeen, Matthews, Smith, and Fontanella to study the relaxation of dipolar defects in calcium fluoride samples doped with two rare-earth species. A new relaxation was reported which falls between the ${R}_{\mathrm{IV}}$ relaxation peaks of the two constituents. We show that the parameters (${\ensuremath{\tau}}_{0}$,$E$) of the Arrhenius relation $\ensuremath{\tau}={\ensuremath{\tau}}_{0}\mathrm{exp}(\frac{E}{\mathrm{kT}})$ which describe the new relaxation peak are interconnected so that the quantity $\frac{(\mathrm{ln}{\ensuremath{\tau}}_{0}^{\ensuremath{-}1})}{E}$ is a bulk property of the host material.