KCd(IO <sub>3</sub> ) <sub>2</sub> Cl: A New UV NLO Crystal with Balanced Optical Properties Engineering via Target‐Driven Multi‐Ion Substitution Strategy
Lei Hou, Siyu Li, Wencong Li, Bingchen Xiao, Yaoqing Chu, Bingbing Zhang, Ying Wang, Xinglong Chen, Lili Liu
Abstract
Abstract The exploration of novel nonlinear optical (NLO) materials plays a pivotal role in advancing laser science and technology. It remains a challenge to achieve a trade‐off among bandgap, second harmonic generation (SHG), and birefringence in NLO crystals. Here, pursuing these target properties, KCd(IO 3 ) 2 Cl, a novel NLO crystal, is rationally designed and synthesized through a multi‐ion substitution strategy. KCd(IO 3 ) 2 Cl crystallizes in the non‐centrosymmetric (NCS) chiral space group P 2 1 2 1 2 1 (No. 19), and it features a 3D framework composing with 2D [Cd(IO 3 )Cl] ∞ layers linked by [I(1)O 3 ] ‒ pyramids. KCd(IO 3 ) 2 Cl exhibits excellent balanced optical properties with strong SHG response (2.2 × KDP), large birefringence (0.18 @ 546 nm), wider optical transparent window (206 nm−12.0 µm), and good thermal stability (up to 392 °C). Notably, KCd(IO 3 ) 2 Cl possesses the shortest UV cutoff edge (≈206 nm) and correspondingly the broadest bandgap (6.0 eV) among the reported NCS inorganic metal iodates. As a promising UV NLO crystal, the discovery of KCd(IO 3 ) 2 Cl not only enriches the iodate halide family but also provides an effective strategy for increasing the bandgap of iodate compounds.