Thermodynamic and electrochemical properties of holmium and HoxAly intermetallic compounds in the LiCl-KCl eutectic
Thermodynamic and electrochemical properties of holmium and HoxAly intermetallic compounds in the LiCl-KCl eutectic
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LiCl-KCl共晶中钬和HoxAly金属间化合物的热力学和电化学性质
DOI：
10.1016/j.electacta.2015.05.161
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发表时间：
2015-08-20
影响因子：
6.6
通讯作者：
Shi, Wei-Qun
中科院分区：
文献类型：
--
作者：
Liu, Kui;Liu, Ya-Lan;Shi, Wei-Qun
本文在684-809K的温度范围内，应用一系列电化学技术，在钨电极上研究了lcl - kcl共晶中钬的电化学性质。在LiCl-KCl共晶中，Ho（III）阳离子的还原是三个电子转移的一步过程。Ho（III）的扩散系数与温度有关，可以表示为ind (Ho(ll)) = 4461T(-1) -5.498。Ho（III）在LiCl-KCl共晶中扩散的活化能为37.09 kJ/mol。Ho（III）的表观标准电位为asE(Ho)((III)/Ho)(theta) (vs.Cl-2/Cl-1) = -3.450 + 5.789 × 10(-4)T/V，在LiCl-KCl共晶中形成HoCl3的表观吉布斯自由能表示为：δ G(HoCl3)(theta) (vs.Cl-2/Cl-1) = 998.62 + 0.1676T （kJ/mol）。采用开路计时电位法（OCP）测定了六种AlyHox金属间化合物在723和773 K温度下的热力学性质。在773 K铝电极上，分别在LiCl-KCl-AlCl3Ho2O3和LiCl-KCl-HoCl3熔体中恒电位电解制备了AlyHox金属间化合物样品。扫描电镜、能谱仪（SEM-EDS）和x射线衍射仪（XRD）鉴定了三种金属间化合物（Al17Ho2、Al3Ho和Al2Ho）的形成。据我们所知，这是第一次用电化学方法得到金属间化合物Al17Ho2。(C) 2015 Elsevier Ltd.版权所有。
This work presents a study of electrochemistry of holmium in the LiCl-KCl eutectic by applying a series of electrochemical techniques on a tungsten electrode at the temperature range of 684-809K. The reduction of Ho(III) cations in the LiCl-KCl eutectic is a one step process with the transfer of three electrons. The diffusion coefficients of the Ho(III) is temperature dependent and can be expressed asInD(Ho(lll)) = 4461T(-1) -5.498. The activation energy for the diffusion of Ho(III) in the LiCl-KCl eutectic was also calculated to be 37.09 kJ/mol. The apparent standard potential of Ho(III) can be described asE(HO)((III)/Ho)(theta) (vs.Cl-2/Cl-1) = -3.450 + 5.789 x 10(-4)T/V and the apparent Gibbs free energy for the formation of HoCl3 in the LiCl-KCl eutectic can be expressed as: Delta G(HoCl3)(theta) (vs. Cl-2/Cl-1) = 998.62 + 0.1676T (kJ/mol). The thermodynamic properties of six AlyHox intermetallic compounds were determined by open circuit chronopotentiometry (OCP) at the temperature of 723 and 773 K. AlyHox intermetallic compound samples were prepared by potentiostatic electrolysis in the LiCl-KCl-AlCl3Ho2O3 and LiCl-KCl-HoCl3 melts on an aluminium electrode at 773 K, respectively. Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (SEM-EDS) and X-ray diffraction (XRD) characterizations identified the formation of three intermetallic compounds (Al17Ho2, Al3Ho and Al2Ho). As far as we know, this is the first time that intermetallic compound Al17Ho2 was obtained by an electrochemical method. (C) 2015 Elsevier Ltd. All rights reserved.