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Trigonal planar units with large polarizability anisotropy and high physicochemical stability are ideal structural units for exploring nonlinear optical (NLO) materials. Integrating the merits of two types of triangular‐like moieties, a family of second‐order NLO‐active hybrid halides, MATX (X = Cl (1), Br (2), and I (3)), are achieved. MATX crystallizes in a nonpolar space group of P6¯$P\overline 6 $2c but exhibits the optimal spatial arrangement and superior NLO performance. The low coordination planar trigonal AgX3 units enable segregation in layers of the three‐winged propeller‐like Me3TPA units. All of the layers are packed in a perfect parallel fashion, making the functional materials exhibit superior NLO performances, including the phase matchable behavior with strong SHG responses (6.2/1, 6.5/2, and 7.6/3 times that of potassium dihydrogen phosphate), large birefringence (0.232/1, 0.252/2 and 0.260/3 at 1064 nm), high laser damage threshold, wide transparent window, and easiness of crystal growth. The first‐principles calculations reveal that the coexistence of strong linear and nonlinear optical properties are ascribed to the synergistic effect of the trigonal moieties. This study points out a useful path for the rational design of excellent NLO materials. [ABSTRACT FROM AUTHOR]

Thioborates are considered new potential mid-infrared nonlinear optical (NLO) crystals with wide band gaps and large second-harmonic generation (SHG) coefficients. Despite the fact that many rare-earth thioborates are structurally non-centrosymmetric, their SHG properties have only been studied very recently and their mid-infrared (Mid-IR) nonlinear optical properties have not yet been studied. In this work, we provide a new synthetic route for LaBS3 (LBS) by solid state reactions of La2S3, B and S with Li2S as flux, and we further study its thermal and optical properties, and theoretically explore the origin of its IR nonlinear optical properties by DFT calculations. Remarkably, LBS possesses balanced properties required for a good Mid-IR NLO crystal, a large SHG effect (1.2 × AgGaS2@2.05 μm – the largest among all known ortho-thioborates), a high laser induced-damage threshold (14 times of AgGaS2), a wide band gap (3.18 eV), a wide infrared transmission range (0.35–25 μm) and high thermal stability. Theoretical calculations suggest that its large SHG effect originates from the synergy effects of the π-conjugated [BS3]3− anions (41.82%) and the [LaS9]15− groups (58.18%). [ABSTRACT FROM AUTHOR]

The first NLO-active metal iodate-phosphates, namely, Cd2(IO3)(PO4) and Cd1.62Mg0.38(IO3)(PO4) (1 and 2), with three types of NLO groups, have been reported. 1 and 2 are isostructural and the structure of 1 features a 3D network formed by the Cd4(IO3)8/4(PO4)6/3 groups. 1 and 2 with strong SHG signals of 4 × and 3.5 × KH2PO4 are promising SHG materials in the visible region. [ABSTRACT FROM AUTHOR]

Three nonlinear optical materials Cd4REO(BO3)3 (RE = Sm, Eu, Tb) have been synthesized through high-temperature solid-state reactions. In their crystal structures, Cd(1)O8 and Cd(2)O6 polyhedra are interconnected via sharing edges and corners into a 3D anion framework with two types of tunnels based on 4- and 7-membered rings; the BO3 groups are grafted into the above-mentioned types, creating new tunnels based on Cd4B3 seven-membered rings, which are filled by RE3+ cations. Powder SHG measurements revealed that the Cd4REO(BO3)3 (RE = Sm, Eu, Tb) samples display SHG signals that are approximately 1.2, 5.6 and 1.5 times that of the KDP sample. In addition, Cd4EuO(BO3)3 and Cd4TbO(BO3)3 emit red and green light, respectively. The lifetime of the Eu(5D0) state for λex,em = 464, 610 nm in Cd4EuO(BO3)3 is measured to be about 1.43 ms whereas the lifetime of the Tb(5D4) state for λex,em = 376, 543 nm in Cd4TbO(BO3)3 is measured to be about 1.01 ms. [ABSTRACT FROM AUTHOR]

An organic–inorganic hybrid polyiodate, namely, [o‐C5H4NHOH]2[I7O18(OH)]⋅3 H2O (I), featuring a novel branched polyiodate chain has been obtained by evaporation method. [o‐C5H4NHOH]2[I7O18(OH)]⋅3 H2O (I) crystalizes in the polar space group Ia and features an [I7O18(OH)]∞2- branched polyiodate chain in which [I3O9]3− trimers are grafted on the same side of the one‐dimensional (1D) chain based on [I4O11(OH)]3− tetramers. The asymmetric organic amine groups are beneficial to the polymerization of iodate groups and inducing the formation of the non‐centrosymmetric (NCS) structure. Compound I exhibits a rather large Second‐Harmonic‐ Generation (SHG) signal of 8.5×KH2PO4 (KDP) upon 1064 nm laser radiation, a moderate band gap of 3.90 eV and a high laser‐induced‐damage‐threshold (LIDT) of 182.34 MW cm−2, hence it is a promising new SHG material. The relationship between the structures of the organic amine groups and the overall structures has been also analyzed. [ABSTRACT FROM AUTHOR]

Exploring new material systems is a highly significant task in the field of inorganic chemistry. A new mixed-valent selenium compound, Hg 3 Se(SeO 3 )(SO 4 ), was successfully synthesized through in situ reactions. This compound exhibits a novel three-dimensional structure composed of Hg 3 Se(SO 4 ) layers bridged by SeO 3 trigonal pyramids. It is the first structure containing (SeO 3 ) 2- , (SO 4 ) 2- , and Se 2- simultaneously. In addition, Hg 3 Se(SeO 3 )(SO 4 ) possesses a wide bandgap (3.5 eV), moderate birefringence (Cal:0.064@546 nm, Exp:0.069@546 nm), a high laser-induced damage threshold (23.35 MW cm -2 ), and a wide transmittance window (0.28-6.6 μm). Our work demonstrates that mixed-valent (+4, -2) selenite selenide can be potential optical materials for the mid-infrared region.

Second-harmonic generation (SHG) response and birefringence are crucial properties for linear and nonlinear optical (NLO) materials, while it is difficult to further optimize these two key properties by using a single traditional functional building block (FBB) in one compound. Herein, a novel IO 4 5- unit is identified, which possesses a square-planar configuration and two stereochemically active lone-pairs (SCALPs). By combining IO 4 5- and IO 3 - units, the first examples of mixed-valent polyiodates featuring an unprecedented bowl-shaped I 5 O 12 - polymerized unit, namely (NH 4 ) 2 (I 5 O 12 )(IO 3 ) and K 1.03 (NH 4 ) 0.97 (I 5 O 12 )(IO 3 ), are successfully synthesized. Excitingly, both crystals exhibit strong SHG responses (16 × KDP and 19.5 × KDP @1064 nm) as well as giant birefringence (∆n exp  = 0.431 and 0.405 @546 nm). Detailed structure-property analyses reveal that the parallel aligned planar IO 4 5- units induce the properly aligned high-density SCALPs, leading to strong SHG response and giant birefringence for both materials. This work not only provides two new potential NLO and birefringent crystals, but also discovers a novel promising FBB (IO 4 5- ) for developing high-performance linear and nonlinear optical materials., (© 2023 Wiley-VCH GmbH.)

Two new mixed-anion cerium iodates, namely, Ce(IO 3 ) 3 F and Ce(IO 3 ) 2 (NO 3 ), have been rationally designed through the integration of hybrid anionic functional building blocks (FBBs). The structure of Ce(IO 3 ) 3 F features a novel [Ce(IO 3 ) 3 F] bilayer, and the material exhibits large birefringence (0.225 @546 nm). The structure of Ce(IO 3 ) 2 (NO 3 ) features [Ce 3 (IO 3 ) 6 ] 3+ triple layers that are further linked by planar NO 3 - units. Ce(IO 3 ) 2 (NO 3 ) shows a moderate SHG response (1 × KDP) and a high laser-induced damage threshold value (22 × AgGaS 2 ). This work demonstrates that the rich coordination geometries of cerium cations facilitate tuning of the structures of related compounds through modulating anionic FBBs.

Organic-inorganic hybrid nonlinear optical (NLO) materials are highly anticipated because of the integration of both merits of the organic and inorganic moieties. Herein, the 2-pyrimidinone cation (C 4 H 5 N 2 O) + has been incorporated into the iodate system to form two polymorphic organic-inorganic hybrid iodates, namely, α- and β-(C 4 H 5 N 2 O)(IO 3 )·HIO 3 . They crystallize in different polar space groups ( Ia and Pca 2 1 ), and their structures feature one-dimensional (1D) chain structures composed of (C 4 H 5 N 2 O) + cations, IO 3 - anions, and HIO 3 molecules interconnected via hydrogen bonds. α- and β-(C 4 H 5 N 2 O) (IO 3 )·HIO 3 exhibit strong and moderate second-harmonic-generation (SHG) responses of 6.4 and 0.9 × KH 2 PO 4 (KDP), respectively, the same band gaps of 3.65 eV, and high powder laser-induced damage threshold (LIDT) values [51 and 57 × AgGaS 2 (AGS)]. The results of theoretical calculations revealed that the large SHG effect of α-(C 4 H 5 N 2 O)(IO 3 )·HIO 3 originated from the IO 3 and HIO 3 groups. This work indicates that (C 4 H 5 N 2 O) + is a potential group for designing new NLO materials with brilliant optical performances.

Inorganic chalcogenides have been studied as the most promising infrared (IR) nonlinear optical (NLO) candidates for the past decades. However, it is proven difficult to discover high-performance materials that combine the often-incompatible properties of large energy gap (E g ) and strong second harmonic generation (SHG) response (d eff ), especially for rare-earth chalcogenides. Herein, centrosymmetric Cs 3 [Sb 3 O 6 ][Ge 2 O 7 ] is selected as a maternal structure and a new noncentrosymmetric rare-earth oxychalcogenide, namely, Nd 3 [Ga 3 O 3 S 3 ][Ge 2 O 7 ], is successfully designed and obtained by the module substitution strategy for the first time. Especially, Nd 3 [Ga 3 O 3 S 3 ][Ge 2 O 7 ] is the first case of breaking the trade-off relationship between wide E g (>3.5 eV) and large d eff (>0.5 × AgGaS 2 ) in rare-earth chalcogenide system, and thus displays an outstanding IR-NLO comprehensive performance. Detailed structure analyses and theoretical studies reveal that the NLO effect originates mainly from the cooperation of heteroanionic [GaO 2 S 2 ] and [NdO 2 S 6 ] asymmetric building blocks. This work not only presents an excellent rare-earth IR-NLO candidate, but also plays a crucial role in the rational structure design of other NLO materials in which both large E g and strong d eff are pursued., (© 2023 Wiley-VCH GmbH.)

A new polar hafnium iodate, CsHfF 4 (IO 3 ), was successfully designed and synthesized by integrating fluorinated hafnium-oxygen polyhedra (HfF 6 O 2 ) and IO 3 - anionic functional groups. Owing to the weak electronic effect of Hf 4+ and the bond-network-induced out-of-center distortion of the HfF 6 O 2 dodecahedra, CsHfF 4 (IO 3 ) achieves a good balance between a strong second-harmonic-generation effect (3.5 × KH 2 PO 4 ) and a rather large band gap (4.47 eV), which is the largest among the d 0 transition-metal iodates. In addition, CsHfF 4 (IO 3 ) possesses a wide transparent region (0.27-9.9 μm), a large birefringence for phase-matching (0.161), and a high laser-induced damage threshold (55.41 MW cm -2 , 26 × AgGaS 2 ) and is nonhygroscopic. This work indicates that the integration of mixed-ligand acentric coordination polyhedra and functional groups containing lone electron pairs is an effective strategy for developing novel inorganic nonlinear-optical materials with balanced overall properties.

Large-sized crystals of the quaternary iodate NaVO 2 (IO 3 ) 2 (H 2 O) (NVIO) with centimeter-scale dimensions (23 mm × 18 mm × 6 mm as a representative) have been successfully grown by the top-seeded hydrothermal method. Linear optical properties have been measured, including the optical transmission spectrum and refractive index. The NVIO crystal possesses an optical window with high transmittance (above 80%) over the range of 500-1410 nm and exhibits strong optical anisotropy with large birefringence Δ n ( n z - n x ) of 0.1522 at 1064 nm and 0.1720 at 532 nm. Based on the measured refractive indices, the phase-matching conditions for second-harmonic generation (SHG) have been calculated, and SHG devices have further been fabricated along the calculated type I and type II phase-matching directions of (θ = 39.0°, φ = 3.8°) and (θ =53.8°, φ = 1.3°). Laser experiments of extra-cavity frequency doubling have been performed on these NVIO devices. It has been confirmed that the effective SHG conversion from 1064 to 532 nm could be achieved with an energy conversion efficiency of 8.1%. Our work demonstrates that large-sized NVIO crystals are promising in the frequency-doubling application.