A thermal and Raman investigation of the phase transitions above room temperature in anhydrous potassium acetate

Abstract Results using thermal and Raman techniques are presented on the phase transition in potassium acetate occurring above room temperature. Two phase transitions are observed at T c 1 = 349K and T c 2 = 413K. The magnitude of the entropy change at T c 1 and the Raman results suggest that this transition is orientational in nature and is due to rotation of the acetate ion about the c-c axis. The T c 2 transition is displacive in nature, and the Raman results show a marked softening of the lowest frequency mode as T c 2 is approached from below.