LiCl-KCl-LaCl_3熔盐体系中La(III)的电化学行为  

Electrochemical Behavior of La(III) in Molten LiCl-KCl-LaCl_3

作　　者：姜涛[1] 田杰[1] 王宁[1] 彭述明[1] 李梅[2] 韩伟[2] 张密林[2] JIANG Tao TIAN Jie WANG Ning PENG Shu-Ming LI Mei HANWei ZHANG Mi-Lin(Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621999, Sichuan Province, P. R. China Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, P. R. China)

机构地区：[1]中国工程物理研究院核物理与化学研究所,四川绵阳621999 [2]哈尔滨工程大学材料科学与化学工程学院,教育部超轻材料与表面技术重点实验室,哈尔滨150001

出　　处：《物理化学学报》2016年第10期2531-2537,共7页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金重大研究计划-集成项目(91426302);国家自然科学基金(21301163)资助~~

摘　　要：在773K条件下,研究了La(III)在LiCl-KCl熔盐中W和Ni电极上的电化学行为。La(III)还原反应是一步三电子转移的准可逆反应;通过在Ni电极上直接电沉积La的方法可以获得La-Ni金属间化合物;恒电位电解可以获得含三种金属间化合物(LaNi5、La7Ni16和La2Ni3)的La-Ni合金层,并且通过X射线衍射仪(XRD)和扫描电镜-能谱分析仪(SEM-EDS)确定物相并表征结构。采用开路计时电位法估算了LaNi5金属间化合物的标准生成吉布斯自由能。揭示了恒电位电解方法是制备La-Ni镀层合金以及提取熔盐中La的有效方法。Electrochemical and thermodynamic studies on the formation of La-Ni intermetallic compounds in molten LiCl-KCl-（3.5%（w））LaCl3 at 773 K were performed. The electrochemical reduction of La（III） ions was investigated on inert W and reactive Ni electrodes by cyclic voltammetry. The reduction potential of La（III）/La on a Ni electrode was observed at more positive potential than that on a W electrode because of the formation of La-Ni intermetallic compounds when La ions reacted with the Ni substrate. Square-wave voltammetry, chronopotentiometry, and open-circuit chronopotentiometry provided further evidence for the formation of La-Ni intermetallic compounds. Potentiostatic electrolysis on a Ni electrode led to the formation of three La-Ni intermetallic compounds, LaNi5, La7Ni16 and La2Ni3, according to X-ray diffraction （XRD） and scanning electron microscopy-energy-dispersive X-ray spectroscopy （SEM-EDS） analyses. The standard Gibbs free energies of formation for LaNi5 were estimated from open-circuit chronopotentiometric measurements using the Gibbs-Helmholtz equation and Hess law. The formation of the La-Ni alloy layer could be controlled by the applied potential and time. Potentiostatic electrolysis was an effective method for electrochemical extraction of La.

关 键 词：LiCl-KCl-LaCl3 La-Ni 镀层合金 吉布斯自由能 

分 类 号：O646.5[理学—物理化学]