DIELECTRIC-RELAXATION IN HYDROGENATED ERBIUM-DOPED CALCIUM-FLUORIDE

Dielectric absorption in hydrogenated CaF2:Er3+ has been studied in the frequency range 8 Hz to 160 kHz, and temperatures between 18.8 K and 295 K. Eight new absorptions have been detected. The temperature dependence of three is non-Arrhenius. It is suggested that phonon assisted, quantum mechanical, tunnelling is involved, as in a previously reported relaxation. In each case the experimental data approximate the expression f(max) = C exp(DT). The rest have energy parameters similar to those in the unhydrogenated material. Suggestions are made about the nature of the defect centres, and of the ionic motions in these centres, using for the analysis infra red and other spectroscopic data obtained by others on similar material.