Electrochemical reduction behavior of Hf(Ⅳ) in molten NaCl–KCl–K_2HfCl_6 system

摘要

The electrochemical reduction mechanism of hafnium ion(Ⅳ) was studied in NaCl–KCl–K_2HfCl_6 melts on a molybdenum electrode. The cyclic voltammetry study shows that Hf(Ⅳ) is reduced to hafnium metal in double two-electron process, that is: Hf(Ⅳ)+2e^-→Hf(Ⅱ) and Hf(Ⅱ)+2e^-→Hf, and the electrochemical reduction of Hf(Ⅳ) process was diffusion-controlled. The diffusion coefficients were calculated at several temperatures, and the results obey the Arrhenius law. According to the relationship of lnD versus 1/T,the corresponding activation energy was determined to be 158.8 kJ ·mol^(-1). The square wave voltammetry results further confirm the reduction mechanism of hafnium.