Energy exchange between ions of Ce3+ and Tb3+ in crystals of fluoride

Spectroscopic study of fluoride crystals with various concentrations of terbium and cerium is performed. Analysis of these spectra shows that change of nature of rare-earth centers takes place under the variation of concentration of rare-earth ions. It leads to modification of energy transfer at various concentrations of rare-earth ions and, as consequence, to modification of observed spectra.