HIGH TEMPERATURE RAMAN STUDY OF SUPERIONIC $LiNaSO_{4}$

Author Institution:$LiNaSO_{4}$ undergoes a structural transition from a hexagonal phase (space group $C_{3v}$) to a superionic body centered cubic phase at approximately $520^{\circ} C$. Symmetry-based assignments are made for the external and internal vibrational modes of the room temperature structure. Modes predominantly due to lithium ion motion are identified through $6_{Li}$ isotope studies. A high temperature Raman study of these modes from ambient through the phase transition temperature is discussed