Abstract
The Raman spectra of a molten NaNO3–AgNO3 mixture are investigated. The variations in frequencies of ν1, 2ν2, ν3 and ν4 with the concentration of silver nitrate were shown and the splittings of ν3 and ν4 were also observed at the region rich in silver nitrate.
Assuming the splitting to be due to the effect of cation field around NO3−, the effect of cation field was estimated by using the Urey-Bradley force field method. It was found that the cation field in the region rich in silver nitrate produced a large effect on the force constants of nitrate ion and such a cation field gradually decreased with decreasing concentration of silver nitrate.
Although it is assumed that the free rotation of nitrate ion about its threefold axis is restricted microscopically in the region rich in silver nitrate as indicated by Wilmshurst, the hinderance of free rotation of NO3− about its threefold axis does not seem to give any effect on the transport parameters for the NaNO3–AgNO3 system.
