Structural phase transformations and temperature dependent Raman spectra of Cs2LiFe(CN)6

Structural phase transformations have been observed for Cs2LiFe(CN)6 at approx.221 and 170 0K. Aspects of the phase II (2210> or =T> or =170 0K) structure have been probed using Raman scattering, x-ray diffraction, and optical methods. The distortion of the cubic (Fm3m) to the tetragonal (I4/m or P4/mnc) cell proceeds along the F/sub 1g/ symmetry rotary mode. The second phase change at 170 0K involves Cs+ translation. Striking differences have been observed in the Raman spectra of the iron and related Cs2LiM(CN)6 (M=Cr+3, Co+3, and Ir+3) salts. These differences are discussed in terms of the dynamic Jahn--Teller distortion in the iron salt which is not present in the related Cr+3, Co+3, and Ir+3 salts