A Raman Spectral Study of the Phase Transitions in Crystalline Potassium Acetate

The lattice mode region of the Raman spectrum of polycrystalline potassium acetate has been measured over a wide temperature range 80 - 500K. The temperature dependent results are consistent with the X-ray work that two phase transitions occur at 349K and 428K respectively. A new phase transition T, around 500K may exist, as detected by thermal expansion study, associated with the softening of a low frequency lattice mode observed in this work.