Effects of Sr2+ content on microstructure and spectroscopic properties of Nd3+ doped Ca1-xSrxF2 transparent ceramics

Abstract CaF2-SrF2 hosts with substitution disorder of Ca2+/Sr2+ sites in the lattice provide lower local symmetry for RE3+ ions compared with pure CaF2 or SrF2 hosts, thereby facilitating more efficient 4f → 4f transitions. Here we report a study of effects of Sr2+ content on microstructure and spectroscopic properties of Nd3+ doped Ca1-xSrxF2 transparent ceramic. Phase and microstructure analyses show that when x is in the range of 0–0.25, Nd: Ca1-xSrxF2 nanoparticles keep pure CaF2 phase with their size, morphology and agglomeration degree mildly changed. Increasing x from 0 to 0.2 significantly improves the luminescence intensity, emission lifetime and emission cross-section of Nd: Ca1-xSrxF2, however, hardly affects the concentration quenching. The luminescence intensities and emission lifetimes of x = 0.2 and 0.25 samples are very close, probably indicating SrF2 phase has already formed in x = 0.25 sample. Based on the spectroscopic properties, the optimal Sr2+ content is found to be x = 0.2.