Investigation of luminescence and optical absorption of K2LiAlF6:Cr3+ single crystals

Photoluminescence, absorption and excitation spectra of K2LiAlF6 single crystals doped with 1% of Cr3+ are presented. The near-infrared photoluminescence observed at room temperature, 77 and 4 K are attributed to the zero-phonon spin-allowed 4T2(4F)→4A2(4F) transition of Cr3+ octahedrally coordinated by F− ions. Lifetimes are obtained. The 4 K emission broad band was described in terms of normal modes of the octahedral complex [CrF6]3−. The Racah, crystal-field and Huang–Rhys parameters are calculated and the quantum efficiency and thermal quenching estimated and compared with Cr3+ properties in different environments.