在 Na3AlF6-Al2O3系熔盐中,考虑到可能出现的键合结构,构建系列铝氟和铝氟氧络合离子的团簇结构模型,分别应用量子化学第一原理(Ab initio)和密度泛函计算方法(DFT)对其进行结构优化和拉曼频率计算,对Na3AlF6-Al2O3二元系含和不含LiF和CaF2添加剂的两种样品进行原位升温拉曼光谱实验。结果表明:两种方法计算结果吻合较好;添加剂LiF和CaF2对Al2O3的溶解有促进作用;溶解Al2O3中的氧已转化成为Al2OF62-中的桥氧,并得到理论计算模拟结果的解释和确认。
Several Al-F and Al-F-O clusters were designed and constructed on the consideration of possible bondings in Na3AlF6-Al2O3 molten salt system. First principle calculation and density function theory (DFT) were applied to optimize the proposed clusters and simulate their vibrational modes and Raman spectra. The samples of binary Na3AlF6-Al2O3 without and with LiF and CaF2 as additives were chosen to recorde by in-situ high temperature Raman spectrometer. The results reveal that the calculation result agrees well with each other. The additives LiF and CaF2 can be help to resolve Al2O3, and oxygen originated from Al2O3 exists as bridging oxygen of A12OF62-anion, which can be confirmed by both experimental and theoretical simulation results.