摘要
采用LiF-CaF_2介质和Yb_2O_3原料的氟盐-氧化物体系电解制得了Ni-Yb合金。通过循环伏安法分析了Yb(Ⅲ)离子的电化学行为,利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)及能谱仪(EDS)表征并分析了电解产物的成分及物相组成。结果表明,在LiF-CaF_2(n(LiF)∶n(CaF_2)=77∶23)的体系中,温度为1 523 K,槽电压4.0 V,以金属Ni为自耗阴极,经3 h电解能成功制备出Ni-Yb合金。Yb(Ⅲ)离子的还原分两步进行,首先Yb(Ⅲ)得到一个电子,被还原为Yb(Ⅱ)离子,随后Yb(Ⅱ)离子在Ni阴极表面继续被还原为Yb并被合金化,最终形成基本组成相为Ni、Ni_5Yb、Ni_(17)Yb_2的合金。充分说明在活性较高的Ni电极表面能够通过去极化作用使Yb(Ⅱ)离子还原电位右移,突破了变价稀土元素Yb(Ⅱ)离子无法在氟盐介质中的惰性电极表面被还原为Yb的限制。
Ni-Yb alloy was prepared by electrolysis of fluorine salt-oxide system with LiF-CaF2 as medium and Yb2O3 as raw material.Cyclic voltammetry was adopted to analyze the electrochemical behavior of Yb(Ⅲ)ions,and X-ray diffraction,scanning electron microscope and energy dispersive spectroscope were employed to characterize the components and phase composition of the Ni-Yb alloys.It can be found from the results that the Ni-Yb alloy was successfully prepared by 3 hours’electrolysis in the LiF-CaF 2-Yb2O3(n(LiF)∶n(CaF 2)=77∶23)eutectic system with self-consumed Ni as cathode at a temperature of 1 523 K and cell voltage of 4.0 V.The implementation of Yb(Ⅲ)reduction includes two steps.Firstly,Yb(Ⅲ)obtained an electron,and was reduced to Yb(Ⅱ).Secondly,the Yb(Ⅱ)ion was reduced to Yb on the surface of Ni cathode.Consequently,the Ni-Yb alloy composed of basic phase Ni,Ni 5Yb,Ni 17 Yb 2 was formed through electrochemical reduction and alloyed process.It is fully demonstrated that the depolarization on active nickel electrode will lead to a positive shift of reduction potential of Yb(Ⅱ),which breaks through the limitation that the variable valence rare earth Yb(Ⅱ)ion can not be reduced to Yb on the surface of the inert electrode in fluorine salt medium.
作者
王旭
廖春发
王瑞祥
孙强超
WANG Xu;LIAO Chunfa;WANG Ruixiang;SUN Qiangcao(School of Metallurgy and Chemical Engineering,Jiangxi University of Science and Technology,Ganzhou 341000)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2019年第5期750-753,共4页
Materials Reports
基金
国家自然科学基金(51564015)
江西省自然科学基金(20161BAB206142)~~
