The influence of oxide ions on the speciation in molten KF containing ZrF₄ and HfF₄ has been studied by using Raman spectroscopy, and identification of the structures is carried out by density functional theory calculations within the polarization continuum model. Zirconium and hafnium fluorides are present as MF₆^2– and MF₇^3– (M = Zr, Hf) in the KF melts with low MF₄ concentrations, whereas MF₆^2– dominate at high MF₄ concentrations. With the addition of 3-5 mol% Li₂O into the KF-MF₄ (10 mol%) melts, oxyfluorides in the form of MOF₅^3– were observed with characteristic terminal M-O stretching bands at 775 (Zr) and 763 (Hf) cm^–1. However, these oxyfluorides were not observed when 5 mol% Li₂O was added into the KF melts with 30-40 mol% ZrF₄ and HfF₄. The formation of MOF₅^3– anion is consistent with the much lower average association energies of MF₇³⁻ than MF₆²⁻. This makes it a lot more favourable to replace F⁻ by O²⁻ so as to generate MOF₅^3–, and the free F^- ions released can further react with MF₆²⁻ to give MF₇³⁻. As the Li₂O concentration is increased to 15 mol%, the melts are no longer homogeneous and the Raman bands due to zirconium and hafnium oxides coming into exist.

已经通过使用拉曼光谱研究了氧化物离子对包含 ZrF ₄和 HfF _{4 的}熔融 KF 形态形成的影响，并且通过在极化连续模型内的密度泛函理论计算来进行结构的识别。锆和铪氟化物以 MF ₆ ^2–和 MF ₇ ^3– (M = Zr, Hf) 的形式存在于具有低 MF ₄浓度的 KF 熔体中，而 MF ₆ ^2–在高 MF ₄浓度下占主导地位。将 3-5 mol% Li ₂ O 添加到 KF-MF ₄ (10 mol%) 熔体中，MOF ₅ ^3–形式的氟氧化物在 775 (Zr) 和 763 (Hf) cm ^–1处观察到特征性末端 MO 伸缩带。然而，当将 5 mol% Li ₂ O 添加到具有 30-40 mol% ZrF ₄和 HfF ₄的 KF 熔体中时，没有观察到这些氟氧化物。MOF ₅ ^3-阴离子的形成与MF ₇ ^3-比MF ₆ ^2-低得多的平均缔合能一致。这使得用O ^2-代替F ^-生成MOF ₅ ^3-更加有利，并且释放的游离F ^-离子可以进一步与MF ₆ ^2-反应。给MF ₇ ³⁻。当 Li ₂ O 浓度增加到 15 mol% 时，熔体不再均匀，并且由于锆和铪的氧化物开始出现拉曼谱带。