Abstract:The ionic structure of acidic NaF-AlF3 melts with different cryolite ratios(CR) was studied in the sealed sample cell by UV laser Raman spectra. The results show that only one kind of Al-F complex ions— exists in the melts with CR=1; However, two kinds of Al-F complex ions, and exist in the acidic melts with CR more than 1. The “lifetime” of decreases increasing with temperature and the main Raman band wavenumber of shows red-shift with increasing CR values, but temperature has little effect on the “lifetime” of . Quantitative analysis of measured Raman spectra results show that in the measuring temperature and weighted-in mole fraction range, temperature has little influence on the mole fraction of anions in the melts, and the content of F− is low. The mole fraction of is about 0.75 for the melts whose weighted-in mole fraction of NaF is 0.6, but that of is about 0.25. When the weighted-in mole fraction of NaF increases to 0.71, the mole fraction of decreases to 0.25 while that of increases to 0.75.

Key words: NaF-AlF3 melts; ionic structure; Al-F complex ions; Raman spectra