Electrochemistry of the Oxofluoro Complexes of Boron in Fluoride Melts

L.P. Polyakova, G.A. Bukatova, E.G. Polyakov, Erik Christensen, Jens H. Von Barner, Niels Bjerrum

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Electrochemical behavior of oxofluoro complexes of boron, synthesized both in situ in FLINAK melt and added into the melt as Na3B3O3F6 compound, was by linear voltammetry within the range of 570-750 oC. It was shown that in lower part of this range the electrochemical reduction of BOF2- complexes follows to ECE mechanism. Growth of temperature makes the electrode proecesses more simple. At 700 oC boron reduces to the elemental state in one irreversible step. Values of diffusion coefficient changes in this interval of temperatures according to the equation: lg D= -1,66 - 3219/T with the activation energy of 61.6 kJ/mol. Study of the thermal stability of boron containing oxofluoro melts showed that O/B ratio changes in time due to evaporation of BF3. As a result borate complexes emerge in the melt alongside with oxofluoro ones.
Original languageRussian
Pages (from-to)674-679
Publication statusPublished - 1997

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