Peculiarities of cascade photon emission and energy storage in M1−xPrxF2+x (M=Ca, Sr, Ba, x≈0.35) crystals

Peculiarities of cascade photon emission (CPE) and energy storage in M1−xPrxF2+x (M=Ca, Sr, Ba, x≈0.35) crystals were studied. The investigation of lattice parameters revealed that these solid solutions belong to the fluorite structure type with the lattice constant noticeably different from that of MF2 crystals. Absorption, emission and excitation spectra of M0.65Pr0.35F2.35 were measured at LHeT and RT. As it turned out the typical for 4f2→4f2 transition in Pr3+ emission lines are broadened as compared with the PrF3 crystal. The analysis of the excitation spectra broadening does not allow bringing out the type of the superlattice, which is inherent to the material, but it indicates clearly the simultaneous presence of different types of the Pr centers in mixed crystals. Yet another specific feature is the higher radiation sensitivity of these fluorides relatively PrF3, MF2 and Pr-doped MF2 crystals. Coloration efficiency enhances in direction Ca→Sr→Ba, and the positions of induced absorption band depend on composition of the solid solution. Colorization, thermo-stimulated luminescence and afterglow of the M1−xPrxF2+x crystals denote high radiation sensitivity as compared with M1−xCexF2+x.