Electrode process of La(Ⅲ)in molten LiCl-KCl
来源期刊：JOURNAL OF RARE EARTHS2009年第6期
论文作者：OUYANG Yinggen CHANG Shangwen WANG Changshui GAO Fanxing LI Ruixue CHANG Li GUO Jianhua LIU Lisheng
Key words：molten LiCl-KCl; electrochemistry; lanthanum chloride; diffusion coefficient; formal potential; rare earths;
Abstract: The electrode process of La(Ⅲ) at Mo electrode in the molten LiCl-KCl for temperatures ranging from 683 K to 773 K was stud-ied by cyclic voltammetry and chronopotentiometry, respectively. The results showed that in the molten LiCl-KCl, reduction of La(Ⅲ) oc-curred in a step with a global exchange of three electrons. Cyclic voltammetry studies indicated that at a sweep rate lower than 0.2 V/s, the electroreduction of La(Ⅲ) to lanthanum metal was reversible and controlled by diffusion of La(Ⅲ). However, the process became under a mixed control of both diffusion and electron transfer when sweep rate exceeded 0.2 V/s. And an empirical temperature dependence of the dif-fusion coefficient of La(Ⅲ) was proposed: InD_(La)(Ⅲ)=7.742-1.441×10~4/T. And the relation between the formal potential of La(Ⅲ)/La versus Ag/AgCl reference electrode and temperature was described in the following equation: E~θ=-1.402-4.689×10~2/T.
OUYANG Yinggen1，CHANG Shangwen1，WANG Changshui1，GAO Fanxing1，LI Ruixue1，CHANG Li1，GUO Jianhua1，LIU Lisheng1
(1.Department of Radiochemistry,China Institute of Atomic Energy,Beijing 102413,China)
Abstract:The electrode process of La(Ⅲ) at Mo electrode in the molten LiCl-KCl for temperatures ranging from 683 K to 773 K was stud-ied by cyclic voltammetry and chronopotentiometry, respectively. The results showed that in the molten LiCl-KCl, reduction of La(Ⅲ) oc-curred in a step with a global exchange of three electrons. Cyclic voltammetry studies indicated that at a sweep rate lower than 0.2 V/s, the electroreduction of La(Ⅲ) to lanthanum metal was reversible and controlled by diffusion of La(Ⅲ). However, the process became under a mixed control of both diffusion and electron transfer when sweep rate exceeded 0.2 V/s. And an empirical temperature dependence of the dif-fusion coefficient of La(Ⅲ) was proposed: InD_(La)(Ⅲ)=7.742-1.441×10~4/T. And the relation between the formal potential of La(Ⅲ)/La versus Ag/AgCl reference electrode and temperature was described in the following equation: E~θ=-1.402-4.689×10~2/T.
Key words:molten LiCl-KCl; electrochemistry; lanthanum chloride; diffusion coefficient; formal potential; rare earths;
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