VIBRATIONAL SPECTRA OF MOLTEN SALTS .6. RAMAN SPECTRA OF INDIUM TRICHLORIDE-ALKALI-METAL CHLORIDE MIXTURES

Raman spectra of molten mixtures of InCl with 1-6 moles LiCl, 1-6 moles KCl, and 1-12 moles CsCl have been obtained over the temperature range 400°-700°C. The 1:1 mixtures all gave essentially similar spectra, which are interpreted as arising from a definite and thermodynamically stable chemical species, InCl4-. The effect of adding further alkali-metal chloride to the 1:1 mixtures varied with the nature of the alkali metal. With KCl and CsCl, spectral changes are consistent with increasing the number of chloride ions associated with each indium, and the formation of InCl5-2 and InCl6-3 species appears likely, though environmental perturbations evidently are severe. However, with LiCl only small changes were observed, and InCl4- appears to remain as the dominant species. Possible interpretations of these data in terms of variations in a quasilattice structure of the melts are discussed. Comparative studies of selected solid and liquid systems are reported, and interpreted in terms of structural rearrangements accompanying'fusion.