KBa3M2F14Cl (M = Zr, Hf): novel short-wavelength mixed metal halides with the largest second-harmonic generation responses contributed by mixed functional moieties

• Published in: Chemical science (Cambridge) Vol. 15; no. 22; pp. 8500 - 8505
• Main Authors: Yan, Mei, Chun-Li, Hu, Ru-Ling Tang, Wen-Dong, Yao, Liu, Wenlong, Sheng-Ping, Guo
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 05.06.2024; The Royal Society of Chemistry
• Subjects: Birefringence; Chemistry; Metal halides; Nonlinear optics; Potassium phosphates; Prisms; Second harmonic generation; Synergistic effect; Zirconium
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d4sc01259c

The development of short-wavelength nonlinear optical (NLO) materials is indispensable and urgently required for further applications. Halides have been disregarded as potential NLO materials with deep-ultraviolet (DUV) cutoff edges due to their weak second-harmonic generation (SHG) response and poor birefringence. Here, two novel and isostructural halides, KBa3M2F14Cl (M = Zr (KBZFC), Hf (KBHFC)), possess structures that are formed by isolated MF7 monocapped triangular prisms and dissociative K+, Ba2+, and Cl− ions. Compared with reported metal halides that are transparent to the DUV region, KBZFC and KBHFC possess the strongest SHG responses (approximately 1, 0.9 × KH2PO4), which are contributed by the synergistic effect of MF7 (M = Zr, Hf) groups, Ba2+ cations, and Cl− ions. The zero-dimensional structures favour sufficient birefringences (0.12, 0.10 @ 1064 nm) for phase-matchable (PM) behaviours. The discovery of KBZFC and KBHFC showcases the potential of NLO mixed metal halides transparent to the DUV region.