ChemInform Abstract: Electrochemical Reduction of Hafnium Tetrachloride in Molten NaCl-KCl

The electrochemical reduction of hafnium tetrachloride has been studied in molten equimolar NaCl-hCl from 700 to 900 o C. Using voltammetry on a tungsten electrode, only the +IV and 0 oxidation states of Hf have been shown to exist in the electrolyte. Convolution analysis has permitted calculation of the diffusion coefficients, and shown that the exchange was quasi-reversible at 700 and 800 o C, but reversible at 900 o C. Fluoride additions led to a more stable fluoro-complex HfF 6 2- , which was reduced in a single step to metallic hafnium. The exchange was shown to be reversible, and the diffusion coefficients were determined, in the 700 to 900 o C temperature range