Nuclear Chemistry Research Division , Korea Atomic Energy Research Institute , 989-111 Daedeok-daero , Yuseong-gu , Daejeon 34057 , Korea.
Department of Radiochemistry & Nuclear Nonproliferation , University of Science and Technology , 217 Gajeong-ro Yuseong-gu , Daejeon 34057 , Korea.
Inorg Chem. 2018 Jul 16;57(14):8299-8306. doi: 10.1021/acs.inorgchem.8b00909. Epub 2018 Jun 28.
The electrochemical reduction of trivalent samarium in a LiCl-KCl eutectic melt produced highly stable divalent samarium, whose electrochemical properties and electronic structure in the molten salt were investigated using cyclic voltammetry, UV-vis absorption spectroscopy, laser-induced emission spectroscopy, and density functional theory (DFT) calculations. Diffusion coefficients of Sm and Sm were electrochemically measured to be 0.92 × 10 and 1.10 × 10 cm/s, respectively, and the standard apparent potential of the Sm couple was estimated to be -0.82 V vs Ag|Ag at 450 °C. The spectroelectrochemical study demonstrated that the redox behavior of the samarium cations obeys the Nernst equation ( E°' = -0.83 V, n = 1) and the trivalent samarium cation was successfully converted to the divalent cation having characteristic absorption bands at 380 and 530 nm with molar absorptivity values of 1470 and 810 M cm, respectively. Density function theory calculations for the divalent samarium complex revealed that the absorption signals originated from the 4f to 4f5d transitions. Additionally, laser-induced emission measurements for the Sm cations in the LiCl-KCl matrix showed that the Sm ion in the LiCl-KCl melt at 450 °C emitted an orange color of fluorescence, whereas a red colored emission was observed from the Sm ion in the solidified LCl-KCl salt at room temperature.
在 LiCl-KCl 共晶熔体中，三价钐的电化学还原生成了高度稳定的二价钐，采用循环伏安法、紫外可见吸收光谱法、激光诱导发射光谱法和密度泛函理论（DFT）计算研究了其在熔融盐中的电化学性质和电子结构。通过电化学测量得到 Sm 和 Sm 的扩散系数分别为 0.92×10 和 1.10×10 cm/s，在 450°C 时，Sm 对的标准表观电位估计为-0.82 V vs Ag|Ag。光谱电化学研究表明，钐阳离子的氧化还原行为符合能斯特方程（E°'=-0.83 V，n=1），三价钐阳离子成功转化为具有 380nm 和 530nm 特征吸收带的二价阳离子，摩尔吸光率值分别为 1470 和 810 M cm。对二价钐络合物的密度泛函理论计算表明，吸收信号源于 4f 到 4f5d 跃迁。此外，LiCl-KCl 基质中 Sm 阳离子的激光诱导发射测量表明，450°C 时 LiCl-KCl 熔体中的 Sm 离子发出橙色荧光，而室温下凝固的 LCl-KCl 盐中的 Sm 离子发出红色发射。
