Knowledge Bank

$LiNaSO4$ undergoes a structural transition from a hexagonal phase (space group $C3v$) 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 $6Li$ isotope studies. A high temperature Raman study of these modes from ambient through the phase transition temperature is discussed.