The first trivalent rare-earth iodate fluoride nonlinear optical (NLO) crystal, Y(IO₃)₂F (YIF), was successfully designed and synthesized, featuring polarization-favorable helical chains constructed from trans-YO₆F₂ polyhedra and IO₃ groups. It exhibited a suitable balance of a wide transparency range of 0.26–10.0 μm, high laser damage threshold (LDT) of 39.6 × AgGaS₂, and moderate second harmonic generation (SHG) effect of 2 × KDP. A series of doped RE:YIF (RE = Pr, Nd, Dy, Ho, Er, Tm, and Yb) crystals were easily synthesized benefiting from the spring-shaped helix structure, which possess wide absorption and emission peaks as well as long lifetime, especially in the visible and near-infrared regions. Particularly, the remarkable fluorescence properties of Nd and Yb doped YIF crystals are comparable to and even better than those of traditional self-frequency doubling (SFD) crystals such as YAB, YCOB, and GdCOB. Thus, these RE-doped YIF crystals are promising laser SFD crystals. This work also indicated that constructing helical chains should be an effective strategy for the design of inorganic polar materials.

中文翻译：

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螺旋结构的极性碘酸稀土氟化物作为激光非线性光学多功能材料

成功设计并合成了首个三价稀土碘酸盐氟化物非线性光学（YLO）Y（IO ₃）₂ F（YIF ）晶体，其特征是由反式-YO ₆ F ₂多面体和IO ₃构成偏振有利的螺旋链组。它显示出适当的平衡，透明度范围为0.26–10.0μm，高激光损伤阈值（LDT）为39.6×AgGaS ₂，以及2×KDP的中等二次谐波（SHG）效果。得益于弹簧形螺旋结构，易于合成一系列掺杂的RE：YIF（RE = Pr，Nd，Dy，Ho，Er，Tm和Yb）晶体，该结构具有宽的吸收和发射峰以及长寿命，尤其是在可见光和近红外区域。尤其是，掺Nd和Yb的YIF晶体具有显着的荧光特性，可以与传统的自倍频（SFD）晶体（如YAB，YCOB和GdCOB）相媲美甚至更好。因此，这些掺RE的YIF晶体是有希望的激光SFD晶体。这项工作还表明，构建螺旋链应该是设计无机极性材料的有效策略。