Infraredhyphen;absorption spectra derived from reflectivity measurements over the range 4000 to 200 cmminus;1have been obtained for molten fluoride solutions of electrochemical interest. The results for alkali fluoride melts containing tantalum (V) over the composition range 21.3 KF:21.3 LiF:TaF5to 2 KF:2 LiF:TaF5show two strong bands which increase in intensity with increasing tantalum concentration. One band is found at 535 cmminus;1and the other is a split (17hyphen;cmminus;1) band centered at 300 cmminus;1. The band positions are independent of concentration and temperature from the melting point to 800deg;C. Comparison of these spectra with those for wellhyphen;characterized solid compounds such as K2TaF7and CsTaF6demonstrate that the TaF72mdash;complex ion is the predominant species in these melts.A study of the influence of cations on the spectra of these melts show that when KF is present TaF72mdash;is the only species observed. In the NaF:LiF solvent, TaF6minus;also appears.The spectra of vapors condensed from the various melts studied show interesting contrasts which are related to the vapormdash;liquid equilibria.
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