Raman Spectra of Simple Ionic Mixtures in Molten Nitrates

Investigations of ionic mixtures in molten NaNO3 and KNO3 by Raman spectroscopy are reported. The solute species include AgNO3, TlNO3, Mg(NO3)2, Ca(NO3)2, Sr(NO3)2, Ba(NO3)2, NaCl, and NaBr. The Raman data show a continuous but gentle shift in certain vibrational frequencies (e.g., ν1). Loss of degeneracy of ν3 in certain mixtures (e.g., Ca++, Sr++, Ba++), and the appearance of the Raman forbidden frequency, ν2, as a weak line (in presence of Tl+) are also observed. The Raman data are discussed relative to current structural concepts for molten inorganic mixtures.