Electrochemistry of Hf(Ⅳ) in NaCl–KCl–Na –K2HfF6 molten salts

作者：Yan-ke Wu; Guo-qing Yan; Song Chen; Li-jun Wang

来源：International Journal of Minerals,Metallurgy and Materials, 2020, 27(12): 1644-1649.

The cathodic reduction mechanism of Hf(Ⅳ) ions in a fused Na Cl–KCl–Na F–K2 HfF6 salt system was studied in various Na F 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 Na F concentrations(0 < molar ratio of [F-/Hf 4+] ≤ 17.39)and one step of Hf(Ⅳ) → Hf at high Na F concentrations(17.39 < molar ratio of [F-/Hf 4+] < 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.