Abstract

Unlike other rare-earth ions the ions of Gd³⁺ have intense luminescence in all solid solutions with fluorite structure as MF₂-GdF₃ where M is Ca, Sr, Ba [1]. The ESR, scanning electron microscopy, optical spectroscopy have been used for the study of MF₂ – GdF₃ structures which included GdF₃ with concentration in the range of 0,001 - 40,000 %. As the results of experiments the three intervals of Gd³⁺ concentration were discovered in CaF₂ - GdF₃ system (below 1%, 1 - 15% and over 15%) characterized by different sets of Gd³⁺ luminescence centers. The peculiarities of the Gd³⁺ luminescence centers are: presence of cubic centers for all concentration intervals of impurity and high concentration of superfluous anion vacancies ${\text{F}}_{\text{v}}^{-}$ in CaF₂ - GdF₃ and SrF₂ - GdF₃ systems. The latter stabilizes a complex claster of Gd³⁺ centers including also interstitial ions of fluorine F_i wich are prevalent type of Gd³⁺ luminescence centers for second and third concentration intervals.

© 1984 Optical Society of America