Analysis of zero-field splitting (ZFS) and local distortion of Cr3+ ions doped into fluoroelpasolite (Cs2NaGaF6 and Cs2NaAlF6) crystals

Zero-field splitting (ZFS) and local distortion of Cr3+ ions doped into fluoroelpasolite (Cs2NaGaF6 and Cs2NaAlF6) crystals at both room temperature and 20 K have been studied using theoretical analyses. The results are discussed in connection with the experimental results. The agreement between the experimental and the present theoretical results indicates that the substitution of Cr3+ occurs for M3+ sites in Cs2NaMF6 crystals. It is shown that the six nearest-neighbor flour atoms have moved from trigonal [1 1 1]-axis more for all sites except for C site in Cs2NaAlF6 when the temperature is lowered from room temperature to 20 K.