A new birefringent material, HfF2(IO3)2, with a large birefringence and improved overall performances achieved by the integration of functional groups

(C5H6.16N2Cl0.84)(IO2Cl2): a birefringent crystal featuring unprecedented (IO2Cl2)− anions and π-conjugated organic cations

“…In the (C 5 H 6. 16 (ICl 4 ) − groups (2.497(1)-2.515(1) Å) reported previously. [17][18][19][20]36 The calculated bond valence value of I(1) is 5.048, conrming its oxidation state of +5.…”

“…4,[10][11][12][13][14] Besides the Sn(II)-based materials, metal iodates containing strong SCALPs are also a class of promising visible birefringent crystals. 15,16 The birefringence of most iodates is in the range of 0.05-0.25 as exemplied by CsIO 3 (Dn cal. : 0.19 at 1064 nm).…”

Optically Anisotropic Mixed-Metal Fluoroiodate Ba2[GaF5(IO3F)] with a Wide Optical Transparent Window and a Moderate Birefringence

“…With the rapid development of ultraviolet (UV) and deep ultraviolet (DUV) technologies in optical communication and display devices, the long-term demand for UV birefringent materials has greatly increased. − Birefringent materials have the property of splitting light and can effectively adjust the light propagation based on polarization, where the incident light can be separated into two diverse rays. Decades of continuous and intensive research has led to the discovery of several commercially available birefringent crystalline materials, including α-BaB 2 O 4 (α-BBO), , YVO 4 , , rutile (TiO 2 ), calcite (CaCO 3 ), and LiNbO 3 , which are widely applied to various optical components, such as phase compensators, optical isolators, polarizers, wave plates, circulators, and beam displacers.…”

“…For example, the basic building units fluorooxoborates [BO x F 4– x ] ( x = 1, 2, and 3) or fluorophosphates [PO x F 4– x ] ( x = 0, 1, 2, 3) in the compounds SrB 5 O 7 F 3 , Li 2 B 6 O 9 F 2 , Na 2 B 6 O 9 F 2 , AB 4 O 6 F (A = NH 4 , Cs) , series, NaNH 4 PO 3 F·H 2 O, (NH 4 ) 2 PO 3 F, and KLa­(PO 2 F 2 ) 4 increase the anisotropic polarizability and result in the enhancement of birefringence. Notably, metal iodate is also a typical birefringent material. , I 5+ cations with stereochemically active lone pairs (SCALP) can constitute unique triangular pyramidal IO 3 – units, which are the preferable functional building motifs to design high-performance birefringent materials with benign optical transparency and large optical anisotropy. ,− However, the energy gap of iodate limited by the SCALP is usually narrow, while adding F anions to metal iodates to form F–M (M = metal) or I–F bonds has been proved to be a feasible method for designing new birefringent materials with large band gaps. ,,− Recently, materials scientists have synthesized some fluoroiodates and metal iodate fluorides with superior optical properties. For example, BaI 2 O 5 F 2 and SrI 2 O 5 F 2 fluoroiodates exhibit large birefringences (0.174 @ 1064 nm and 0.203 @ 532 nm, respectively) and band gaps (4.30 and 4.20 eV, respectively). , HfF 2 (IO 3 ) 2 and SnF 2 (IO 3 ) 2 iodate fluorides also possess large birefringences (0.333 @ 550 nm and 0.234 @ 1064 nm, respectively) and wide energy gaps (4.11 and 4.08 eV, respectively).…”

CsHfF4(IO3): A Hafnium Iodate Exhibiting a Strong Second-Harmonic-Generation Effect and a Wide Band Gap Achieved by Mixed-Ligand Acentric Coordination

“…Hafnium iodates have not been investigated as NLO materials so far because of the weak electronic effect distortion of the Hf 4+ cation. 44 We propose that the introduction of F − ions into HfO m polyhedra to obtain asymmetric HfF n O m−n polyhedra with increased bond-network structural distortions may be an effective way to compensate for the weak electronic distortions of the Hf 4+ cations and to achieve the NLO properties of the materials. On the basis of the above ideas, we have been working on the hafnium iodate fluoride system in a bid to develop new NLO materials with balanced properties in terms of SHG effects and band gaps.…”