Uranium tetrafluoride (UF₄) is an important intermediate in the production of UF₆ and nuclear fuel. Historical characterization of UF₄ with Raman spectroscopy was plagued with ambiguity until the first accurate Raman spectrum was published by our group in 2016. Although generally considered to be relatively stable, UF₄ can hydrolyze to form numerous UF₄ hydrates that may play a role in future uranium waste forms. In contrast to anhydrous UF₄, the hydrates, with their OH stretch and HOH bending modes, can be spectroscopically characterized by the type and degree of water bonding in the crystal lattice, which can yield additional information about their crystal structure. Herein, vibrational spectroscopy (Raman and infrared) was used to characterize three different UF₄ hydrates: UF₄(H₂O)_0.33, U₃F₁₂(H₂O), and UF₄(H₂O)_2.5. Spectra show the different hydrates vary in the number of observed bands, full-width half-maximum of the bands, and band intensity. These differences are due to varying interactions between the OH stretch and HOH bending modes with UF₄ and the polymeric UF₄ structure in the crystal lattice. These vibrational data, in combination with spectral fitting and crystallographic structures measured with powder X-ray diffraction and single crystal X-ray diffraction, provide unique details on the location of water molecules in the crystal lattice of hydrated UF₄, and provide an interesting contrast to the vibrational spectra of anhydrous UF₄.

四氟化铀 (UF ₄ ) 是生产 UF ₆和核燃料的重要中间体。使用拉曼光谱对 UF _{4 的}历史表征一直存在歧义，直到我们小组于 2016 年发表了第一个准确的拉曼光谱。 虽然通常认为 UF ₄相对稳定，但 UF ₄可以水解形成许多 UF ₄水合物，这些水合物可能在未来的铀废物形式。与无水 UF _{4 相比}，具有 OH 拉伸和 HOH 弯曲模式的水合物可以通过晶格中水键的类型和程度进行光谱表征，这可以产生有关其晶体结构的额外信息。在此，振动光谱（拉曼和红外）用于表征三种不同的 UF ₄水合物：UF ₄ (H ₂ O) _0.33、U ₃ F ₁₂ (H ₂ O) 和 UF ₄ (H ₂ O) _2.5. 光谱显示不同的水合物在观察到的条带数量、条带的半峰全宽和条带强度方面有所不同。这些差异是由于 OH 拉伸和 HOH 弯曲模式与 UF ₄和晶格中的聚合 UF ₄结构之间的相互作用不同。这些振动数据，结合粉末 X 射线衍射和单晶 X 射线衍射测量的光谱拟合和晶体结构，提供了水分子在水合 UF ₄晶格中位置的独特细节，并提供了有趣的对比无水UF ₄的振动光谱。