Luminescence of Heavily Ce-Doped Alkaline-Earth Fluorides

Luminescent and structural properties of M
_1-x
Ce
_x
F
_2+x
(M=Ca, Sr, Ba, 0.15₂
crystal. A partial deficiency in the fluorine positions as well as excessive fluorine in interstitial sites was revealed. Crystal lattice modification does not strongly affect the basic absorption and emission properties as compared with weakly Ce-doped MF
₂
. The spectral-kinetic parameters of solid solutions luminescence are similar to those of Ce
³⁺
ion in perturbed site in CeF
₃
lattice. Low light yield of mixed compounds is connected with the small Stokes shift and reabsorption. The probable model of perturbed Ce
³⁺
center in M
_1-x
Ce
_x
F
_2+x
crystals assumes the presence of interstitial fluorine in the nearest or next nearest neighborhood of the cerium ion.