Structure of Molten Nitrates. III. Vibrational Spectra of LiNO3, NaNO3, and AgNO3

The Raman spectra of the molten nitrates of lithium, sodium, and silver change as the temperature is raised. Close to the melting point well-developed low-frequency modes can be distinguished close to the exciting line while at higher temperature these have become somewhat broader but still quite distinct. There are also changes in the magnitude of the splitting of degenerate modes and in the energy of the other vibrations. The spectra have been interpreted on the basis of a quasicrystalline model in which cubic packing is assumed. Spectral changes from the solid, volume change on fusion, entropy changes, and molten-state radial distribution functions are explained on the basis of the model.