To develop high‐performance nonlinear optical (NLO) materials for infrared (IR) applications, we have applied a rational element‐composition design strategy and investigated the unexplored PbO–PbCl₂–PbI₂ system. By doing so, we discovered a new polar lead mixed oxyhalide, Pb₁₈O₈Cl₁₅I₅, the first synthetic metal oxyhalide combining both Cl⁻ and I⁻. Pb₁₈O₈Cl₁₅I₅ reveals an unprecedented structural feature with two different dimensional types of oxocentered Pb–O units, namely, [O₄Pb₈]⁸⁺ clusters and [OPb₂]²⁺ chains. Centimeter‐sized single crystals of Pb₁₈O₈Cl₁₅I₅ have been successfully grown under ambient conditions. Remarkably, Pb₁₈O₈Cl₁₅I₅ satisfies all fundamental yet rigorous criteria for high‐performance IR NLO materials, exhibiting the widest IR transparency (up to 16.0 μm) among oxide‐based crystals, strong second‐harmonic generation response (1.05×AgGaS₂), superior birefringence (0.086 at 636 nm), and a high laser‐induced damage threshold (8.5×AgGaS₂).

中文翻译：

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Pb18 O8 Cl15 I5：具有前所未有的结构和出色的红外非线性光学性能的极性混合氧卤化物。

为了开发用于红外（IR）应用的高性能非线性光学（NLO）材料，我们应用了合理的元素组成设计策略并研究了未开发的PbO–PbCl ₂ –PbI ₂系统。通过这样做，我们发现了一个新的极性引线混合卤氧化物，铅₁₈ Ø ₈氯₁₅我₅，第一合成金属卤氧化物结合两种氯^-我^- 。Pb ₁₈ O ₈ Cl ₁₅ I ₅揭示了一种前所未有的结构特征，具有以氧心为中心的Pb-O单元的两种不同尺寸类型，即[O ₄ Pb ₈] ⁸⁺簇和[OPb ₂ ] ²⁺链。厘米大小的Pb ₁₈ O ₈ Cl ₁₅ I ₅单晶已在环境条件下成功生长。值得注意的是，Pb ₁₈ O ₈ Cl ₁₅ I ₅满足高性能IR NLO材料的所有基本但严格的标准，在氧化物基晶体中表现出最宽的IR透明性（高达16.0μm），强大的二次谐波生成响应（1.05× AgGaS ₂），优异的双折射（636 nm处为0.086）和较高的激光损伤阈值（8.5×AgGaS ₂）。