Wu Chao, Jiang Xingxing, Lin Lin, Dan Wenyan, Lin Zheshuai, Huang Zhipeng, Humphrey Mark G, Zhang Chi
China-Australia Joint Research Center for Functional Molecular Materials, School of Chemical Science and Engineering, Tongji University, Shanghai, 200092, China.
Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
Angew Chem Int Ed Engl. 2021 Dec 20;60(52):27151-27157. doi: 10.1002/anie.202113397. Epub 2021 Nov 22.
Deep-ultraviolet (deep-UV) nonlinear optical (NLO) crystals are key materials in creating tunable deep-UV lasers for frequency conversion technology. However, practical application of the sole usable crystal, KBe BO F , has been hindered by the high toxicity of beryllium and its layering tendency in crystal growth. Herein, we report a beryllium-free deep-UV NLO material NaSr (OH)(B O )[B(OH) ] (NSBOH), synthesized by a covalent bond modification strategy under hydrothermal conditions. Moisture-stable NSBOH exhibits strong second-harmonic generation (SHG) at 1064 nm (3.3 × KH PO ) and 532 nm (0.55 × β-BaB O ), both amongst the largest powder SHG responses for a deep-UV borate, with good phase-matchability and a short wavelength cutoff edge (below 190 nm). NSBOH possesses a 3D covalent anionic [B O ] honeycomb-like framework with no layering. The Sr and Na ions, residing in the cavities of the anionic framework, act as templates for the assembly and favorable alignment of NLO-active groups, resulting in an optimal balance between strong SHG activities and wide UV transparency. These merits indicate NSBOH is a very attractive candidate for deep-UV NLO applications.
深紫外（deep-UV）非线性光学（NLO）晶体是用于频率转换技术的可调谐深紫外激光器的关键材料。然而，唯一可用的晶体KBe₂BO₃F₂，由于铍的高毒性及其在晶体生长中的分层倾向，其实际应用受到了阻碍。在此，我们报道了一种无铍的深紫外NLO材料NaSr(OH)(B₃O₆)[B(OH)₄]（NSBOH），它是在水热条件下通过共价键修饰策略合成的。对水分稳定的NSBOH在1064 nm（3.3×KH₂PO₄）和532 nm（0.55×β-BaB₂O₄）处表现出强烈的二次谐波产生（SHG），这两者都是深紫外硼酸盐中最大的粉末SHG响应之一，具有良好的相位匹配性和短波长截止边（低于190 nm）。NSBOH拥有一个无分层的三维共价阴离子[B₃O₆]蜂窝状框架。位于阴离子框架空腔中的Sr和Na离子充当NLO活性基团组装和有利排列的模板，从而在强SHG活性和宽紫外透明度之间实现了最佳平衡。这些优点表明NSBOH是深紫外NLO应用中极具吸引力的候选材料。
