Luminescence of heavily Ce-doped alkaline-earth fluorides

The spectral and kinetic parameters of M1−xCexF2+x (x=0.35, M=Ca, Sr, Ba) crystals luminescence have been studied. These characteristics are compared to the luminescence of solution base hosts: MF2:Ce and CeF3. The emission bands of heavily Ce-doped alkali earth fluorides are closed to the spectrum of perturbed Ce-center in CeF3 at T=9 K. Luminescence of M0.65Ce0.35F2.35 crystals reveals the efficient excitation in the UV and VUV ranges. The main feature of the emission and excitation spectra of Ce3+ luminescence is the displacement to the low-energy range according to the bandgap decrease in the Ca-, Sr- and Ba-based fluorides, respectively. Small Stokes shift leads to the reabsorption and light yield decrease. Luminescence peculiarities of M1−xCexF2+x solid solution and the role of Ce-enriched inclusions are discussed.