2024 - Sustainable Industrial Processing Summit
SIPS 2024 Volume 4. Kanatzidis Intl. Symp / Solid State Chemistry and Materials
| Editors: | F. Kongoli, M.A. Alario-Franco, I. Chung, M. Delferro, O. Farha, H. Kageyama, F. Marquis, A. Navrotsky, A. Tressaud, P. Trikalitis |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2024 |
| Pages: | 222 pages |
| ISBN: | 978-1-998384-10-5 (CD) |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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GIANT BIREFRINGENCE ACHIEVED VIA HYDROGEN BOND-CLICK REACTION FOR ENHANCED COPLANARITY
Ling Chen1;1BEIJING NORMAL UNIVERSITY, Beijing, China;
Type of Paper: Invited
Id Paper: 446
Topic: 52
Abstract:
Birefringent crystals serve as crucial elements in optical devices, as they exhibit anisotropic refractive indices along different crystal directions. This optical anisotropy stems from the anisotropies of both structural geometry and spatial electron distribution. Consequently, the planar structural building units are excellent choices for constructing birefringent crystals. However, achieving an anisotropic crystal structure (especially a coplanar geometry) poses a significant challenge. Herein, we propose a novel hydrogen bond-click reaction concept to unravel the giant birefringence in (C5H6ON)+(NO3)–, (4HPN) for the first time. We demonstrate that the interactions between the planar hydrogen bond donor (4-hydroxypyridinium, C5H6ON+ cation) and planar hydrogen bond acceptor (NO3– anion) ensure the coplanarity during the crystal packing, generating the desired optical anisotropy. At 546 nm, several as-obtained (001)-single crystal wafers (#1–4) measure 
varying from 0.331 to 0.358; and two manually cut chips (#5,6) read 
= 0.469, 0.494, respectively. These values are smaller than the DFT calculated maximal value (
= nY – nX = 0.593 at 546 nm). Since 4HPN has heavy (001)-growth habit, the maximal ∆n has not been observed yet. Nevertheless, the observed ∆n values on 4HPN with an Eg = 3.70 eV already surpass that of the commercialized benchmark crystals, e.g., YVO4 ( = 0.232, 
= 3.1 eV) and CaCO3 (∆nobv = 0.174, = 5.4 eV), commonly used in the UV to visible and near IR spectral range. 4HPN also exhibits a strong second harmonic generation (SHG = 9.55 × KDP measured at 1064 nm). This unique concept offers a promising avenue for the design and development of birefringent crystals with potential applications in optical communication, sensing and signal processing devices.