摘要
Nonlinear optical(NLO)materials currently attract significant interest and hold paramount importance in the optoelectronic field.Nevertheless,the fabrication of NLO crystals capable of transmitting ultraviolet to mid-infrared wavelengths remains a formidable challenge.Herein,we synthesized two novel NLO crystals,namely Cs_(3)REGe_(3)O_(9)(RE=Y,Gd),by employing a structural gene strategy that harmoniously merges flexible[YO_(6)]and[GdO_(6)]octahedra with rigid[GeO4]motifs.Remarkably,Cs_(3)REGe_(3)O_(9)(RE=Y,Gd)crystals exhibit substantial band gaps of 4.92 and 5.3 eV,respectively,while achieving the shortest reported ultraviolet cutoff edges at 210 and 215 nm among the boron-free germanate-based NLO materials.Importantly,these compounds also feature a remarkably broad infrared transparency range exceeding 6.8μm.Furthermore,both compounds demonstrate a moderate second-harmonic-generation(SHG)response,comparable to that observed in KDP.Additionally,first-principles calculations unveil that the synergistic effect of the[REO_(6)]octahedra and[GeO_(4)]tetrahedra plays a pivotal role in governing the optical properties of Cs_(3)REGe_(3)O_(9)(RE=Y,Gd).These explored findings offer a novel avenue for leveraging the highly desired NLO materials in the region spanning from ultraviolet to mid-infrared wavelengths.
基金
financially supported by the National Natural Science Foundation of China(Grant No.52002273,61835014 and 51890864)
National Key R&D Program of China(2021YFA0717800).
