Structural and vibrational study of chromium doped elpasolite crystals Cs_2NaAlF_6

摘要

The influence of site-symmetry and electron phonon coupling in Cs_2NaAlF_6: Cr~(3+) is probed by correlation of optical and sturctural measurements. Based on neutorn and x-ray analysis the structure is a distorted R3m, exhibiting a unique stacking interaction. Selection rules have been used to assign the Raman-active zone-center vibrations. Although local and bulk mode frequencies differ slightly, indicating that the guest Cr~(3+) ion does not significantly perturb the host structure, vibrational analysis indicates the Cr~93+) ion is coupled to the first corrdination sphere of the Al-F lattice.