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采用方波伏安法,在石墨电极上测定了NdF_3-LiF-Nd_2O_3熔盐体系中氧离子的氧化过程。得出了氧离子氧化峰值电流密度Ip和Nd_2O_3浓度之间的关系曲线,通过最小二乘法建立了如下的方程式:Ip=0.09594[Nd2O3]+0.00497。由该方程式得到的氧化钕浓度(%,质量分数)与X射线荧光光谱(XRF)测试结果比较,平均误差为5.405%。通过方波伏安曲线及该方程式表征了Nd_2O_3在NdF_3-Li F熔盐中的溶解度和溶解速度。Nd_2O_3在NdF_3-Li F熔盐中的溶解是一个吸热过程。随着温度的升高,Nd_2O_3的溶解度呈线性增加,随着Nd F3浓度的增加,Nd_2O_3溶解度也随之增加。温度为1200℃时,当支持电解质中NdF_3浓度从70%(质量分数)增加到90%(质量分数)时,Nd_2O_3溶解度增加1.3%,Nd_2O_3在NdF_3-Li F熔盐中溶解速率在10 min左右达到最大值,该值与电解质组成几乎无关。当NdF_3∶Li F=90∶10(质量比),T=1200℃条件下氧化钕的溶解速度在10~20 min内保持最大值,其值为0.057%·min-1。
The oxidation process of oxygen ions in NdF 3 -LiF-Nd 2 O 3 molten salt system was measured on graphite electrode by square-wave voltammetry. The relation curve between the peak current density Ip and the concentration of Nd_2O_3 was obtained. The least square method was used to establish the following equation: Ip = 0.09594 [Nd2O3] +0.00497. The neodymium oxide concentration (%, mass fraction) obtained from this equation was compared with the XRF test results with an average error of 5.405%. The square wave voltammetry curve and the equation were used to characterize the solubility and dissolution rate of Nd_2O_3 in NdF_3-LiF molten salt. The dissolution of Nd_2O_3 in NdF_3-LiF molten salt is an endothermic process. With the increase of temperature, the solubility of Nd_2O_3 increases linearly. With the increase of Nd_ (F3) concentration, the solubility of Nd_2O_3 also increases. When the NdF 3 concentration in supporting electrolyte is increased from 70% to 90% (mass fraction) at 1200 ℃, the solubility of Nd 2 O 3 increases 1.3%, and the dissolution rate of Nd 2 O 3 in the molten salt of NdF 3-Li F is about 10 min The maximum is reached, which has little to do with the electrolyte composition. When NdF_3:Li F = 90:10 (mass ratio), the dissolution rate of neodymium oxide kept the maximum within 10 ~ 20 min at T = 1200 ℃, and its value was 0.057% · min-1.