Effects of Charge Compensation on the Absorption Spectrum of Yb3+ in Cadmium Fluoride

Abstract

The absorption spectrum of Yb³⁺ in CdF₂ has been found to consist of two spectra which are distinguishable on the bases of differences in integrated absorption intensity, temperature dependence, and effects resulting from impurity compensation. One spectrum is similar to those observed for Yb³⁺ in yttrium gallium garnet and YbCl₃·6H₂O and is little affected by impurity compensation, nor does it exhibit any unusual temperature dependence. The other spectrum, which strongly resembles that for Yb³⁺ in aqueous solution, is markedly sensitive to both temperature and impurity compensation. Optical correlations with the extent of impurity compensation and lattice parameter suggest that one of the spectra is due to an associative interaction between Yb³⁺ and interstitial F⁻, and that interstitial F⁻ is removed in a quantitative manner by the impurity compensator Na⁺.