As structural variants of famous hexagonal tungsten bronzes, hexagonal tungsten oxides (HTO) represent an important family with fascinating functional properties, such as piezoelectric, ferroelectric, pyroelectric, and nonlinear optical (NLO) properties. However, none of them are transparent in the deep-UV spectral region, which limits their applications. Herein, we report the first HTO-type monofluorophosphate K₃Sc₃(PO₄)(PO₃F)₂F₅ (I) with deep-UV transparency. Such a monofluorophosphate is NLO-active with a phase-matchable powder second harmonic generation efficiency of 0.9 times that of KH₂PO₄ at 1064 nm. Importantly, the UV-Vis reflectance spectrum indicates that it is deep-UV transparent down to 200 nm. This work pushes the transparent window of NLO materials with HTO-type structures down to the deep-UV spectral region for the first time and opens up a new door for HTO materials.

作为著名六方钨青铜的结构变体，六方氧化钨 (HTO) 代表了一个重要的家族，具有迷人的功能特性，例如压电、铁电、热电和非线性光学 (NLO) 特性。然而，它们在深紫外光谱区域中都不是透明的，这限制了它们的应用。在此，我们报告了第一个具有深紫外透明性的 HTO 型单氟磷酸盐 K ₃ Sc ₃ (PO ₄ )(PO ₃ F) ₂ F ₅ ( I )。这种单氟磷酸盐具有 NLO 活性，相位匹配的粉末二次谐波产生效率是 KH ₂ PO _{4的 0.9 倍}在 1064 纳米。重要的是，UV-Vis 反射光谱表明它在低至 200 nm 的深度紫外线下是透明的。该工作首次将具有HTO型结构的NLO材料的透明窗口推向深紫外光谱区域，为HTO材料打开了新的大门。