Huang Yi, Chu Dongdong, Zhang Yong, Xie Congwei, Li Guangmao, Pan Shilie
Research Center for Crystal Materials; State Key Laboratory of Functional Materials and Devices for Special Environmental Conditions; Xinjiang Key Laboratory of Functional Crystal Materials; Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, 40-1 South Beijing Road, Urumqi, 830011, China.
School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, 150001, China.
Angew Chem Int Ed Engl. 2024 Aug 19;63(34):e202406576. doi: 10.1002/anie.202406576. Epub 2024 Jul 17.
Oriented synthesis of functional materials is a focus of attention in material science. As one of the most important function materials, infrared nonlinear optical materials with large second harmonic generation effects and broad optical band gap are in urgent need. In this work, directed by the theoretical structure prediction, the first series of non-centrosymmetric (NCS) alkali-alkaline earth metal [PS]-based thiophosphates LiCaPS (Ama2), NaCaPS (P2), KCaPS (Pna2), RbCaPS (Pna2), CsCaPS (Pna2) were successfully synthesized. Comprehensive characterizations reveal that ACaPS4 could be regarded as promising IR NLO materials, exhibiting wide band gap (3.77-3.86 eV), moderate birefringence (0.027-0.064 at 1064 nm), high laser-induced damage threshold (LIDT, ~10×AGS), and suitable phase-matching second harmonic generation responses (0.4-0.6×AGS). Structure-properties analyses illustrate that the Ca-S bonds show non-ignorable covalent feature, and [PS] together with [CaS] units play dominant roles to determine the band gap and SHG response. This work indicates that Li-, Na- and K- analogs may be promising infrared nonlinear optical material candidates, and this is the first successful case of "prediction to synthesis" involving infrared (IR) nonlinear optical (NLO) crystals in the thiophosphate system and may provide a new avenue to the design and oriented synthesis of high-performance function materials in the future.
功能材料的定向合成是材料科学中备受关注的焦点。作为最重要的功能材料之一，具有大二次谐波产生效应和宽光学带隙的红外非线性光学材料亟待开发。在这项工作中，在理论结构预测的指导下，首次成功合成了第一系列非中心对称（NCS）的碱金属 - 碱土金属[PS]基硫代磷酸盐LiCaPS（Ama2）、NaCaPS（P2）、KCaPS（Pna2）、RbCaPS（Pna2）、CsCaPS（Pna2）。综合表征表明，ACaPS4可被视为有前景的红外非线性光学材料，具有宽带隙（3.77 - 3.86 eV）、适中的双折射（1064 nm处为0.027 - 0.064）、高激光诱导损伤阈值（LIDT，约为10×AGS）以及合适的相位匹配二次谐波产生响应（0.4 - 0.6×AGS）。结构 - 性能分析表明，Ca - S键呈现出不可忽视的共价特征，并且[PS]与[CaS]单元在决定带隙和SHG响应方面起主导作用。这项工作表明，锂、钠和钾的类似物可能是有前景的红外非线性光学材料候选物，这是硫代磷酸盐体系中首次成功实现涉及红外（IR）非线性光学（NLO）晶体的“预测到合成”案例，并且可能为未来高性能功能材料的设计和定向合成提供一条新途径。
