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A non-centrosymmetric metal-free thiophosphate, γ-P4S3I2, was successfully designed and synthesized by polymorphism strategy, and featured paralleled (P4S3I2)n molecular clusters and exhibited promising nonlinear optical (NLO) performances.

It is generally considered difficult for traditional sulfates to exhibit strong second harmonic generation (SHG) responses and large birefringence values because SO4 groups are nonpolar tetrahedral structures.

By introducing the strongly electronegative F− ions into [SO4] tetrahedral units, polar NLO-active units [(BeS)O4F2] were obtained, thus forming 1D zigzag [(BeO3F)–(SO3F)]∞ chains.

The flexible (C3H2O4)2− groups were employed to design a new mixed alkali malonate KLi(C3H2O4)·H2O as an potential UV NLO crystal achieving the balance between strong SHG efficiency and moderate birefringence.

We herein report two asymmetric germanate crystals, KNbGe3O9 and K3Nb3Ge2O13, with different structures and optical properties derived from divergent polymerized forms of GeO4 and NbO6 groups. Remarkably, K3Nb3Ge2O13 achieved a rare combination of the strongest second harmonic generation (SHG) response of 17.5×KDP@1064nm and the largest birefringence of 0.196@546nm in germanates. It features unique [Nb3O12]∞ tubular chains constructed by circular Nb3O15 tripolymers. Theoretical calculations reveal that the d-p interactions in the Nb3O15 group are responsible for outstanding optical properties. This work emphasizes the significance of the polymerizable functional units in obtaining high-performance nonlinear optical (NLO) crystals.

Hg3AsSe4X (X = Br and I) derived from honeycomb layered topology of GaSe, achieved superior optical properties including strong SHG effects, suitable band gaps, large birefringence and wide IR transparency range.

The first examples of metal trifluoroiodates, namely, M4O(IO3)3(I3O7F3)BF4 (M = Pb, Sr), have been synthesized. Both compounds feature an interesting windmill-shaped [I3O7F3]2– trimer polyfluoroiod...

Two tellurium(IV)-based sulfate nonlinear optical (NLO) materials, Te2O3(SO4) and Te(OH)3(SO4)·H3O, were successfully synthesized via the mild hydrothermal method. Te2O3SO4 has a two-dimensional (2D) structure consisting of [Te6O12]∞ layers as well as [SO4] groups. Te(OH)3(SO4)·H3O features a simple 0D structure made up of an isolated [TeO3] pyramid and a [SO4] tetrahedra. Both of them are phase-matching materials and show remarkable powder second harmonic generation (SHG) efficiencies about 6 and 3 times that of KH2PO4 (KDP), respectively, for Te2O3SO4 and Te(OH)3(SO4)·H3O. Especially for Te(OH)3(SO4)·H3O, in addition to a large SHG response, it possesses a short UV cutoff edge (∼233 nm) as well as moderate birefringence (0.052@546.1 nm). Furthermore, theoretical calculations confirmed that their strong SHG effects are due to the synergistic effect of the [TeO3] pyramid and [SO4] tetrahedra.

Balancing the second-harmonic generation (SHG) coefficient, band gap, and birefringence is a vital but addressable challenge for designing infrared nonlinear optical materials. By applying a "rigidity-flexibility coupling" strategy, a quaternary diamond-like phosphide, Mg2In3Si2P7, with wurtzite-type superstructure was successfully designed and synthesized. Remarkably, it achieved the rare coexistence of giant second-harmonic generation (2 × ZnGeP2 and 7.1 × AgGaS2), suitable band gap (2.21 eV), moderate birefringence (0.107), and wide IR transparent range (0.56-16.4 μm). First-principles calculations revealed that the giant SHG response and large birefringence can be attributed to the synergy of arrangement-aligned [InP4] and [SiP4] tetrahedra. This work not only opens a new avenue for designing advanced infrared nonlinear optical materials but also may spur more explorations on quaternary diamond-like pnictides.

To obtain new nonlinear optical (NLO) materials with a large second harmonic generation (SHG) effect has always been a great challenge. We have synthesized the first metal borate-iodate NLO crystal, Be2 (BO3 )(IO3 ) (BBIO), by multicomponent modification of KBe2 BO3 F2 (KBBF), in which the structural features of KBBF were maintained and (IO3 )- groups were connected to honeycomb [Be2 BO3 O2 ]∞ layers. As the first KBBF family member with mixed anionic groups, BBIO benefited from the synergistic effect of (IO3 )- , (BO3 )3- and (BeO4 )6- groups, and exhibited a very strong SHG response of ≈7.2×KH2 PO4 (KDP, @1064 nm) and a large birefringence (Δn) of 0.172 at 1064 nm. BBIO may, unexpectedly, optimize growth habits via van der Waals forces. This study presents borate-iodate as a new NLO material and it demonstrates opportunities in KBBF structural engineering.

Tongue muscles are derived from mesodermal cells, while signals driven by cranial neural crest cells (CNCCs) regulate tongue myogenesis via tissue-tissue interaction. Based on such mechanisms of interaction, congenital tongue defects occur in CNC-related syndromes in humans. This study utilized a pathologic model for the syndrome of congenital bony syngnathia, Wnt1-Cre;pMes-Bmp4 mouse line, to explore impacts of enhanced CNCCs-originated BMP4 signal on tongue myogenesis via tissue-tissue interaction. Our results revealed that microglossia, a clinical phenotype of congenital bony syngnathia in humans exhibited in Wnt1-Cre;pMes-Bmp4 mice due to impaired myogenesis. The augmented BMP4 signal affected the distal distribution, proliferation, and differentiation of myogenic cells as well as tendon patterning, resulting in disarrangement and atrophy of tongue muscles and the loss of the anterior digastric muscle. This study demonstrated how a CNCCs-originated ligand impaired tongue myogenesis via a non-autonomous way, which provided potential formation mechanisms for understanding tongue abnormalities in CNC-related syndromes.

Two polymorphic phosphide-based infrared (IR) nonlinear optical (NLO) crystals, α-Ca2CdP2 and β-Ca2CdP2, were obtained by combining alkaline-earth metals and d10 transition metals using metal flux and metal salt flux methods, respectively. The crystal structure of α-Ca2CdP2 is orthorhombic in the space group Cmc21 (no. 36), while the structure of β-Ca2CdP2 is monoclinic in the space group Cm (no. 8). Both are two-dimensional layered structures that are composed of CdP4 tetrahedra layers via sharing vertices, which stack along the b-axis and the c-axis, respectively. The second harmonic generation (SHG) measurements manifest that α-Ca2CdP2 and β-Ca2CdP2 exhibit strong SHG intensities (1.41 and 3.28× that of AgGaS2 at a 2050 nm laser, respectively). Other optical measurements indicate that α-Ca2CdP2 and β-Ca2CdP2 have suitable band gaps (1.98 and 1.55 eV, respectively), high laser-induced damage thresholds (4.5 and 3.1× that of AgGaS2 at 1064 nm laser, respectively) and appropriate birefringence (0.12 and 0.20 at 2050 nm, respectively) in addition to covering wide infrared transparent regions. The research on α-Ca2CdP2 and β-Ca2CdP2 demonstrates that they are potential IR NLO candidates. Theoretical calculations uncover that their SHG effects are from distorted CdP4 tetrahedra, highlighting that tetrahedral motifs, including d10 transition metals, would be ideal NLO-active building blocks.

The first tellurium(II) thiourea sulfate semiorganic nonlinear optical (NLO) material, Te(CS(NH2)(2))(4)SO4 center dot 2H(2)O, was successfully obtained using the slow evaporation technique. The structure of this metal-free crystal featured three types of NLO-active units, namely CS(NH2)(2), (SO4)(2-), and (TeS4)(6-), which synergistically contributed to its moderate second harmonic generation response (2.4 x KDP@1064 nm) and large birefringence (0.210@ 546.1 nm). Remarkably, this is the first example in which the quadrangular (TeS4)(6-) groups significantly contributed to the SHG effect and birefringence, and the first principles calculations revealed its special mechanism of NLO activity. These findings highlighted the exploration of semiorganic NLO materials and provide new opportunities for the discovery of new NLO crystals.

Over the last few decades, the development of each new nonlinear optical (NLO)-active functional unit has led to the discoveries of a series of excellent NLO materials. In the present work, based on first-principles studies, we identified a novel deep-UV (DUV) NLO-active functional unit, a non-π-conjugated group viz. (NH 2 SO 3 ) - . By combining alkaline-earth metals with (NH 2 SO 3 ) - group , two DUV transparent NLO sulfamates , M(NH 2 SO 3 ) 2 (M = Sr, Ba) with superior optical properties including strong SHG responses (1.2 and 2.7 × KH 2 PO 4 (KDP)), short UV cut-off edge (< 190 nm) and moderate birefringence (0.056@589.3 nm for Sr(NH 2 SO 3 ) 2 ) were successfully synthesized. Our work has provided not only two promising DUV transparent NLO crystals, but also an innovative non-π-conjugated unit for developing more DUV transparent NLO materials.

[PO4]3− possesses small microscopic second-order susceptibility and polarizability anisotropy, which inherently result in weak second-harmonic generation (SHG) and small birefringence. Herein, a new noncentrosymmetric phosphate, [C(NH2)3]3PO4·2H2O, was successfully designed and synthesized by a solution evaporation method. [C(NH2)3]3PO4·2H2O without metal ions is composed of planar conjugated guanidine cations and PO4 tetrahedrons, which are connected by hydrogen bonds, forming a three-dimensional network. Physical property measurements indicate that the title compound displays an SHG response of 1.5 × KH2PO4 (KDP) and a larger birefringence (0.055@546.1 nm) compared with most reported ultraviolet nonlinear optical phosphates. Furthermore, first-principles calculations reveal that the π-conjugated planar [C(NH2)3]+ cations and [PO4]3− groups are responsible for its excellent linear and NLO properties.

Continuously, nitrides are mainly regarded as semiconductors or thermal conductivity materials and applied in photonic devices. In this work, we proposed that nitrides may also be a new system for ...

One new combination, alkali-metal and alkaline earth-metal selenite fluoride, LiBa3Bi6(SeO3)7F11 (LBBSF) and its analogue Ba3Bi6.5(SeO3)7F10.5O0.5 (BBSF) were reported here for the first time. Unusual aliovalent cation substitution between them affected the layer thickness and made the bond strains of [SeO3] enhanced, thereby inducing greater distortions and affecting the SHG efficiencies. This work may provide thoughts for exploring new NLO materials.

Two structural polymorphs of CdP2, including orthorhombic α-CdP2 (Pna21) and tetragonal β-CdP2 (P41212/P43212), were synthesized through one chemical transport reaction and one solid-state reaction...

Currently, to obtain new ultraviolet (UV) nonlinear optical (NLO) materials with large second-harmonic generation (SHG) response and short SHG phase-matching cutoff wavelength (λPM) is still very challenging. Herein, through evolving the KBe2BO3F2 (KBBF) structure to a carbonate system, a novel hydroxycarbonate UV NLO crystal, NaZnCO3(OH), was successfully synthesized. It not only possessed the typical structural characteristics of KBBF but also enhanced the bonding force between functional layers. Remarkably, in this crystal, the rare coexistence of a very large SHG response of 5.2 × KH2PO4 (KDP, @1064 nm) and short type-I SHG λPM of 201 nm had been achieved, indicating that it was a promising UV NLO crystal. This work showed the great significance of KBBF structure evolution and provided new opportunity to design UV NLO materials with good performance.

To design pnictide nonlinear optical materials with wide band gap and large second-harmonic generation, the heavy halogen I was introduced into pnictides through anionic aliovalent substitution with diamond-like ZnS as templates. Thus, four excellent halopnictide-based infrared nonlinear optical crystals, MII3 PnI3 (MII =Zn, Cd; Pn=P, As), were obtained. They all exhibited defect diamond-like structures with highly parallel-oriented [MII PnI3 ] mixed-anionic tetrahedral groups, leading to excellent physical properties including wide band gaps (2.38-2.85 eV), large second harmonic generation responses (2.7-5.1×AgGaS2 ), high laser-induced damage thresholds (5.5-10.7×AgGaS2 ), and good IR transparency. In particular, Cd3 PI3 and Cd3 AsI3 achieved phase-matching (Δn=0.035 and 0.031) that their template β-ZnS could not do. Anionic aliovalent substitution provides a feasible strategy to design novel promising halopnictide IR NLO materials.

Two new alkaline earth barbiturates, Ca(H3C4N2O3)2·H2O and Sr(H5C8N4O5)2·4H2O, were synthesized via the mild hydrothermal technique. For Ca(H3C4N2O3)2·H2O, the stacking (H3C4N2O3)- anions along the c axis are interconnected by CaO7 polydedra forming a three-dimensional structure. Also, for Sr(H5C8N4O5)2·4H2O, it has two-dimensional layers composed by SrO7 polyhedra and (H5C8N4O5)- anions. The (H5C8N4O5)- anions can be seen as two (H3C4N2O3)- anions connected each other via the N-C bond. Powder second-harmonic generation (SHG) measurements revealed that Ca(H3C4N2O3)2·H2O is a phase-matchable material with a moderate SHG response (ca. 1.15× that of KDP). Furthermore, the birefringence values of the two crystals were measured as 0.49 and 0.475 at 546.1 nm, respectively. The theoretical calculations showed that the SHG response and large birefringence were primarily caused by the (H3C4N2O3)- and (H5C8N4O5)- groups.

A family of noncentrosymmetric alkali-metal bismuth selenite fluorides, A2Bi2(SeO3)3F2 [A = K(1) and Rb(2)], has been synthesized through a mild hydrothermal method. These isostructural compounds a...

Ionic inorganic-organic ultraviolet (UV) nonlinear optical (NLO) materials have gradually become attractive because they can integrate their advantages into one. In this study, the first noncentros...

The first fluorosulfonic ultraviolet (UV) nonlinear optical (NLO) material, C(NH2 )3 SO3 F, is rationally designed by taking KBe2 BO3 F2 (KBBF) as the parent compound. C(NH2 )3 SO3 F features similar topological layers as KBBF by replacing inorganic (BO3 )3- with organic C(NH2 )3 + trigonal units and BeO3 F with SO3 F- tetrahedra. Therefore, C(NH2 )3 SO3 F is a metal-free UV NLO crystal. Benefiting from the coplanar configuration of the C(NH2 )3 + cationic groups, it possesses a large SHG response of 5×KDP and moderate birefringence of 0.133@1064 nm. Besides, it has a short UV cutoff edge of 200 nm. The calculated results reveal the shortest SHG phase-matching wavelengths can reach 200 nm. These findings highlight the exploration of metal-free compounds as nontoxic and low-cost UV NLO materials as a new research area.

An alkaline-earth-metal iodate fluoride, Ba(IO3)F (1), was discovered by introducing F atoms into alkaline-earth-metal iodates via a hydrothermal method. The pseudo-two-dimensional (2D) [BaF]+ laye...

An ammonium-containing metal iodate fluoride compound, (NH4 )Bi2 (IO3 )2 F5 , featuring a two-dimensional double-layered framework constructed by [BiO2 F5 ]6- and [BiO4 F4 ]9- polyhedra, as well as [IO3 ]- groups, was successfully synthesized. The well-ordered alignment of these SHG-active units leads to an extraordinary strong SHG response of 9.2 times that of KDP. Moreover, this compound possesses a large birefringence (Δn=0.0690 at 589.3 nm), a wide energy band gap (Eg =3.88 eV), and a high laser damage threshold (LDT; 40.2×AgGaS2 ). In particular, thermochromic behavior was observed for the first time in this type of compound. Such multifunctional crystals will expand the application of nonlinear optical materials.

Two ternary infrared nonlinear optical materials Cd4SiS6 (1) and Cd4SiSe6 (2) with polar space group Cc were obtained by mixing d10 configurations-central tetrahedra motifs and NLO-active distorted...