Effects of Cr 3! concentration on the optical properties of Cs 2 NaAlF 6 single crystals

This work is devoted to the study of optical properties of the elpasolite Cs2NaAlF6 with 0.1, 1.0, 3.0, 10.0, 30.0 and 50.0% of Cr 3! ions. The interest in this system lies on the fact that it presents a high quantum yield in the visible and infrared regions and therefore can be considered for laser applications. The photoluminescence and excitation spectra were obtained at 5 and 300 K, while the absorption spectra were measured at 300 K. The spectra at 300 K show broad bands attributed to the Cr 3! ions in two non-equivalent sites, both of them with octahedral coordination, while at 5 K we can observe the vibrational modes of the (CrF6) 3" complex. The ensemble of our results lead us to conclude that the material has potential applications as a lasing system.