Abstract
The cathodic reduction mechanism of Hf(IV) ions in a fused NaCl–KCl–NaF–K2HfF6 salt system was studied in various NaF concentrations at 1073 K to obtain a purified dendritic Hf metal. The results of cyclic voltammetry and square wave voltammetry indicated that the reduction process comprised two steps of Hf(IV) → Hf(II) and Hf(II) → Hf at low NaF concentrations (0 < molar ratio of [F−Hf4+] ≤ 17.39) and one step of Hf(IV) → Hf at high NaF concentrations (17.39 < molar ratio of [F−/Hf4+] < 23.27). The structure and morphology of the deposits obtained in potentiostatic electrolysis in the one-step reduction process were analyzed and verified by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectrometry. In the one-step reduction process, the disproportionation reaction between the Hf metal and Hf complex ions was inhibited, and a large dendrite Hf metal was achieved in molten salt electrorefining.
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This work was financially supported by the National Natural Science Foundation of China (No. 51204021).
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Wu, Yk., Yan, Gq., Chen, S. et al. Electrochemistry of Hf(IV) in NaCl–KCl–NaF–K2HfF6 molten salts. Int J Miner Metall Mater 27, 1644–1649 (2020). https://doi.org/10.1007/s12613-020-2083-3
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DOI: https://doi.org/10.1007/s12613-020-2083-3