稀土氧化物Gd2O3、Nd2O3、Sm2O3和Dy2O3在KCl-LiCl-Li2O熔盐中的电解

采用循环伏安法和计时电位法研究了Li₂O在KCl-LiCl熔盐中的电化学行为，并利用卷积伏安法计算了923 K下O₂^-在KCl-LiCl熔盐中的扩散系数（D)，得到D=0.5×10^-5 cm²/s。以Gd₂O₃、Nd₂O₃、Sm₂O₃和Dy₂O₃为阴极，在KCl-LiCl-Li₂O(w=1%)熔盐中进行电解（恒电压3.40 V、电解温度923 K、电解时间25 h）。通过X射线衍射分析(XRD)，证实稀土氧化物被部分还原为金属，并分析了电解过程中可能发生的反应。同时利用PRS模型（该模型可将固态阴极内离子的极限扩散速率与固态氧化物孔隙P、金属/氧化物摩尔体积R、阴极还原后的体积收缩率S等参数关联）分析了这些稀土氧化物的电解还原模型，得到Gd₂O₃、Nd₂O₃、Sm₂O₃和Dy₂O₃的最优孔隙率分别为18.7%、24.2%、30.6%、16.7%，最短电解时间分别为133、157、143、119 h，将这些结果与电解实验结果进行对比，发现阴极的孔隙率和电解时间均不满足金属氧化物完全被还原的要求，并给出了相应的解释。

Electrolysis of Rare Earth Oxides(Gd2O3, Nd2O3, Sm2O3 and Dy2O3) in KCl-LiCl-Li2O Molten Salt

The electrochemical behavior of Li2O in KCl-LiCl molten salt has been studied by cyclic voltammetry and chronopotentiometry. The diffusion coefficient D=0.5×10^-5 cm²/s of O₂^- in KCl-LiCl molten salt at 923 K has been calculated by convolutional voltammetry. Gd₂O₃, Nd₂O₃, Sm₂O₃ and Dy₂O₃ were used as cathodes to conduct electrolysis in KCl-LiCl-Li₂O(w=1%) molten salt(constant voltage 3.40 V, electrolysis temperature 923 K, electrolysis time 25 h). By XRD analysis, it was confirmed that the rare earth oxides are partially reduced to metals, and the possible reactions during the electrolysis process were analyzed. At the same time, the PRS model was used to analyze the electrolytic reduction models of these rare earth oxides, and the optimal porosity(Popt) of Gd₂O₃, Nd₂O₃, Sm₂O₃ and Dy₂O₃ are 18.7%, 24.2%, 30.6%,16.7%, respectively. The minimum electrolysis time of them are 133, 157, 143, and 119 h, respectively, which are compared with the results of the electrolytic experiment, it is found that the porosity and electrolysis time of the cathode do not meet the requirements for complete reduction of metal oxides, and the corresponding explanation is given.