Lattice dynamical calculations of deficient NaCl superstructure-type Li 2CoCl 4 and Li 2MnBr 4

Abstract

Lattice dynamical calculations on SnMn 2S 4-type (ordered deficient NaCl superstructure) Li 2CoCl 4 and Li 2MnBr 4 were performed using a short-range force constant model. The results obtained reveal that the assignments of the Raman active phonon modes (and those of the structure related Suzukitype Li 6 M II X 8) reported in the literature have to be changed. The 11 hitherto unknown infrared active modes have been calculated to range 233–339 and 70–98 cm −1, and 227–266 and 50–71 cm −1 for Li 2CoCl 4 and Li 2MnBr 4, respectively.