Short Edge Research Articles (Page 1)

Birefringent crystals are widely used in modern optical devices for their ability to modulate the polarization state of light. Exploring birefringent crystals with large birefringence (Δn > 0.3) and short ultraviolet (UV) cutoff edge is still a challenge. Protonated melamine groups are candidates for designing birefringent crystals with excellent performance due to its high microscopic polarizability anisotropy. However, its potential for constructing large birefringent crystals has not been fully exploited due to limitations in the density and arrangement of its lattice structure. This study employed a strategy of multiple hydrogen bond-induced molecular ordered assembly to successfully synthesize three excellent birefringent crystals with supramolecular framework: (C3N6H7)BF4 (MelBF), (C3N6H7)H2PO4 (MelPO), and (C3N6H7)2PO3F·4H2O (MelPOF). It is worth noting that new compound MelBF exhibits a large birefringence of 0.44 at 546 nm and a short UV cutoff edge of 228 nm. Here, tetrahedral anions containing highly electronegative O/F atoms synergistically regulate and optimize the dihedral angle and density of the protonated melamine planar ring groups through multiple hydrogen bonding interactions to synthesize crystals with both high birefringence and short UV cutoff edges. This study confirms the potential of multiple hydrogen bonds-driven molecular assembly for designing advanced birefringent crystals with excellent optical properties.

The synthesis of materials possessing substantial birefringence, particularly in the short-wave ultraviolet spectral range, continues to pose a significant challenge in optical materials science. This work reports the discovery of a new compound, CN4H7B3O3F2(OH)2, in the hydroxyfluorooxyborate category. It is synthesized by strategically selecting [CN4H7] groups with a wide HOMO-LUMO gap and substantial polarizability anisotropy as cations, while rationally modifying the B-O anionic groups through fluorination and hydroxylation. This compound exhibits a large birefringence value of Δnexp = 0.185 and a short UV absorption edge at 209 nm, making it a promising candidate for short-wave ultraviolet birefringent crystal materials.

Abstract Developing new short‐wavelength nonlinear optical (NLO) crystals has always been a significant and challenging area of research. Herein, guided by the cooperative optimization strategy, three new rare‐earth metal borate fluorides, K2GdB3O6F2, Rb2LuB3O6F2, and Cs2LuB3O6F2, are rationally designed and fabricated by synergically assembling advantageous functional groups. Among them, a structural evolution from centrosymmetric K2GdB3O6F2 to non‐centrosymmetric Rb2LuB3O6F2 and Cs2LuB3O6F2 reveals that the [B3O6] group contributes to the control of structural symmetry, owing to its sensitivity to the coordination of rare earth metal polyhedra. Notably, all the three title compounds exhibit short cutoff edges less than 200 nm, with Cs2LuB3O6F2 displaying a large experimental frequency doubling effect of 1.5 × KH2PO4. The type‐I shortest phase‐matching wavelengths for Rb2LuB3O6F2 and Cs2LuB3O6F2 are evaluated to be 210 and 202 nm, respectively, indicating their potential for direct output of 213 coherent lights through a fifth harmonic generation process of Nd: YAG laser. This study provides new insights into the rational design and development of short‐wavelength NLO materials by exploring the sensitivity of the [B3O6] groups to the surrounding coordination environment, thereby fostering innovation in the field of NLO materials.

Polar crystal materials hold significant potential for advanced scientific and technological applications; however, their synthesis remains challenging due to stringent symmetry requirements. In this work, flexible π-conjugated malonate groups with high polarity and diverse conformations were employed as polar functional basic modules (FBMs) to overcome this challenge. Three new crystals, RbLi(C3H2O4)·H2O, Rb2Li(C3H3O4)3·H2O, and C(NH2)3(C3H3O4), were successfully synthesized via a deprotonation-regulated conformational switching strategy. Remarkably, all three compounds crystallize in polar space groups and simultaneously exhibit strong second-harmonic generation responses (1.5-3.0 × KH2PO4 (KDP)), large birefringence (0.043-0.163@546 nm), and short UV cutoff edges (230-244 nm). This study not only discovers three promising UV polar crystals but also elucidates the conformational evolution of malonate-based FBMs, offering valuable guidance for the rational design of new polar crystal materials.

The fiber patch placement (FPP) technology enables the automated manufacturing of complex-shaped components. However, placement defects such as bridging and wrinkling may occur during the deposition of patches onto the tool surface, which are typically unacceptable in high-performance applications. To analyze and prevent such defects, this study investigated the patch placement process using finite element (FE) simulations. Various obstacle geometries were designed to deliberately induce wrinkling, and these scenarios were subsequently simulated. Furthermore, simulations and experimental placements were carried out on an aerospace demonstrator. The simulation results were validated using 3D scan data, and typical placement defects were successfully replicated in the numerical model. The maximum deviation between scanned and simulated patches was 4.49 mm, corresponding to only 3% of the patch’s short edge length. This confirms the suitability of the approach for capturing key defect mechanisms. The placement behavior of the FPP technology has not yet been investigated using simulations validated with 3D scan data. The findings contribute to a deeper understanding of defect formation mechanisms—particularly wrinkling and bridging—under defined placement conditions. This work provides a foundation for predictive process optimization and the development of defect-preventing placement strategies for complex geometries.

Zero-order waveplates play pivotal roles in polarization manipulation and laser technology, yet the fabrication of zero-order waveplate crystals that simultaneously exhibit small birefringence, a large bandgap, and a wide infrared (IR) transmission range remains a challenge. In this work, a novel germanate optical crystal, Sr2CdGe3O9 (SCGO), featuring isolated rigid [Ge3O9] clusters, was identified through spontaneous crystallization. SCGO demonstrates remarkable thermal stability, with an incongruent melting point of 1054 °C. Importantly, SCGO displays a favorable low birefringence of 0.006@1064 nm, superior to that of the commercially available waveplate crystal α-SiO2 (0.0092@532 nm). Additionally, this crystal exhibits an enlarged bandgap of 4.7 eV, a notably short UV cutoff edge at 225 nm, outperforming most germanates containing transition metals, along with an extended IR transmission window up to 6.0 μm. These exciting optical properties highlight the potential of SCGO as a zero-order waveplate crystal spanning from the UV to mid-IR wavelength range. The presence of isolated [Ge3O9] groups in the SCGO structure introduces a weak structural anisotropy, opening up new avenues for exploring zero-order waveplate materials in wide wavelength ranges.

The development of nonlinear optical (NLO) crystal materials with short ultraviolet cutoff edges is of great significance to laser applications and industrial development. Based on acentric AE-M-F22 (Sr5Zr3F22 (1), Ca5Zr3F22 (2), and Ca5Hf3F22 (3), with AE = alkaline earth metal and M = Zr, Hf), a novel hydrated zirconium-based fluoride, K5NaZr4F22(H2O)2 (4), was obtained through a cosubstitution strategy involving mixed alkali metal cations. K5NaZr4F22(H2O)2 crystallizes in the C2 space group and presents a unique three-dimensional {[Zr4F22(H2O)2]6-}∞ anion framework composed of hydrogen-bonded {[Zr4F23(H2O)2]7-}∞ chains. 1-4 exhibit phase-matched second-harmonic generation (SHG) responses and short ultraviolet cutoff edges. This work has brought about a novel structure of zirconium fluoride and enriched the family of NLO zirconium/hafnium fluorides.

The sulfonamide group (SO2(NH2)2) shows great potential for deep-ultraviolet nonlinear optical (NLO) crystals due to its strong hyperpolarizability and anisotropy, but its neutrality and poor protonation limit its application. Here, we propose a new design strategy that introduces an ionic framework via halide salts to both stabilize sulfonamide molecules and control their orientation, thereby enabling desirable second-harmonic generation (SHG) and birefringence. Following this concept, the first sulfonamide fluoride, KF·[SO2(NH2)2], was successfully synthesized, with SO2(NH2)2 units firmly anchored in the KF lattice by K─O ionic and N─H···F hydrogen bonds. Remarkably, this crystal exhibits a unique and compact Cairo pentagonal configuration. Benefiting from its well-ordered structure, the crystal exhibits a strong SHG response of 1.4×KDP at 1064nm, a large birefringence of 0.079@546nm, and a short cutoff edge below 190nm. This work opens new avenues for the design of advanced NLO crystals with a sulfonamide group.

Nonlinear optical (NLO) materials are vital for advanced optical applications, particularly in the laser industry. While borate-based NLO crystals have been extensively studied, recent research has expanded to novel materials featuring flexible organic π-conjugated systems. In this work, we report the synthesis of a new ultraviolet NLO crystal [C(NH2)3][NH2(CH2COO)2], which crystallizes in the noncentrosymmetric monoclinic space group Pc (No. 7). The structure is composed of a three-dimensional network formed by the [C(NH2)3]+ cation and the flexible π-conjugated [NH2(CH2COO)2]- anion, linked through hydrogen bonding and Coulombic interactions. Optical measurements reveal a short ultraviolet cutoff edge at 216 nm, a significant birefringence (0.194 at 546.1 nm), and a notable second-harmonic generation response (1.5 × KDP). Theoretical calculations suggest that synergistic interactions between the cation and anion group enhance the material's anisotropic polarizability and hyperpolarizability, positioning it as an excellent candidate for high-performance ultraviolet NLO applications. This study demonstrates the potential of combining flexible organic anions with strategically selected cations to design advanced NLO materials for next-generation optical devices.

Three new isostructural crystals, A3ZnNO3X4 (A = Rb, NH4; X = Cl, I) were synthesized via a mild aqueous solution method by combining π-conjugated [NO3] groups with d10 transition-metal Zn2+ ions, crystallizing in the orthorhombic space group Pnma (No. 62). All of the three compounds produce millimeter-sized crystals, with (NH4)3ZnNO3Cl4 yielding crystal as large as 17 × 14 × 4 mm3. Notably, compared with Rb3ZnNO3I4 (Δn = 0.051@546 nm), (NH4)3ZnNO3Cl4 exhibits a short UV cutoff edge (below 243 nm) and significantly enhanced birefringence (Δn = 0.085@546 nm), while (NH4)3ZnNO3I4 achieves the highest birefringence value (Δn = 0.091@546 nm) among the three crystals, demonstrating the potential as excellent UV birefringent crystals. Theoretical calculations reveal that the large birefringence of the three crystals primarily originates from the planar [NO3] triangles. Detailed analysis further attributes the differences in birefringence to variations in the cation and halide sizes.

There is an immediate demand for identifying birefringent materials that possess substantial optical anisotropy to meet the requirements of photonic applications. Optimizing the orientation of functional modules to achieve enormous anisotropy is essential for enhancing the linear optical properties of birefringent materials. In this research, the arrangement of anionic groups was regulated by the hydrogen bonds formed between group (CN4H7)+ and (H2C3N3S3)- groups, and coupled with the synergistic effect of the repulsive force between the same groups, this resulted in the design and synthesis of the first metal-free trithiocyanurate ultraviolet (UV) birefringent crystal (CN4H7)H2C3N3S3. It realized a robust trade-off between the short UV cutoff edge (336 nm) and large birefringence (0.319@546.1 nm). Remarkably, its UV cutoff edge is significantly blue-shifted, and its birefringence is much greater than that of all the documented (CN4H7)+-based compounds. According to theoretical calculations, the optical properties of (CN4H7)H2C3N3S3 are primarily influenced by (CN4H7)+ and (H2C3N3S3)-. This study provides a viable approach for developing high-performance UV birefringent crystals in systems containing only π-conjugated groups.

A new barium zincophosphite BaZn2(HPO3)3 is obtained via a simple hydrothermal reaction. BaZn2(HPO3)3 crystallizes in the P space group and exhibits a novel 3D crystal structure. It possesses a short ultraviolet cutoff edge of 205 nm, corresponding to a large experimental bandgap of 5.55 eV. BaZn2(HPO3)3 also has good thermal stability. This present work provides a comprehensive characterization of its crystal structure and optical properties. Additionally, first‐principles calculations are employed to analyze the structure–activity relationship of BaZn2(HPO3)3.

Rational structural design of inorganic materials remains a significant challenge in materials science, particularly for deep-ultraviolet (DUV) nonlinear optical (NLO) crystals. Herein, a new DUV-transparent NLO borate, CsSrB3O6 (CSBO), has been successfully predicted and synthesized by the cation regulation from Cs2KY(B3O6)2 (CKYBO). The structural stability of CSBO was confirmed by first-principles phonon vibration calculations, and it was eventually synthesized via a high-temperature solid-state reaction. The substitution of K+/Y3+ cations with Sr2+ cations eliminates the disorder and significantly reduces the thermal expansion anisotropy (CKYBO: 9.32, CSBO: 1.95), which effectively protects the crystals from cracking during crystal growth. Furthermore, CSBO successfully achieved the ordered design of B3O6 functional groups, and this structural feature enables it to display well-balanced functional performance, including a strong second-harmonic generation response (5.0 × KH2PO4), a short UV absorption edge (<190 nm), and moderate birefringence (0.075@1064 nm). All of these results demonstrate that CSBO is a promising DUV NLO material, and this study establishes an effective strategy for developing high-performance NLO crystals through synergistic computational-experimental approaches.

ABSTRACTBorate‐based hybrids offer an excellent platform for advanced materials design, yet integrating multiple functional units remains challenged by competing structural requirements. Here, we presented a rationally designed hybrid system that first achieves synergistic coupling between π‐conjugated malonate and polymerized boro‐oxygen units through precise coordination chemistry control. We synthesized eight new malonate‐borate hybrids comprising two structural types: series I ([B3O7(OH)]‐based) and series II ([H3BO3]‐based). Starting from three centrosymmetric series I compounds, controlled variation of stoichiometry and reaction pathways yielded four non‐centrosymmetric series II hybrids and one centrosymmetric series II phase, enabling tailored structural symmetry. The series II system exhibits diverse functional properties across the material series, including a high birefringence (Δn = 0.203@546 nm) with a short cutoff edge of 200 nm, strong second‐harmonic generation responses rivaling KH2PO4 (KDP), and high ionic conductivity. This work establishes a new paradigm for functional crystal engineering by elucidating fundamental design principles for balancing competing property requirements through controlled structural evolution.

Noncentrosymmetric compounds have attracted extensive research interest due to their unique functional properties, including second-harmonic generation (SHG), ferroelectricity, and piezoelectricity. In this study, four alkali metal pyrophosphate crystals, Li2Rb2P2O7, LiK2RbP2O7, LiRb2NaP2O7, and LiRb3P2O7, were identified through A-site cation substitution. By manipulating different alkali metal cations, the former two compounds crystallize in the acentric space groups Pca21 (No. 29) and C2221 (No. 20), while the latter two compounds crystallize in the centrosymmetric space groups P21/c (No. 14) and Pnma (No. 62), respectively. The unique structural frameworks of these compounds are composed of [P2O7] dimers and [LiO4] tetrahedra. These crystals demonstrate short UV absorption cutoff edges around 200 nm along with wide bandgaps. Notably, Li2Rb2P2O7 and LiK2RbP2O7 exhibit a moderate powder SHG effect, approximately 0.2 times that of KDP (KH2PO4). First-principles calculations were performed to elucidate the origin of optical activities in these compounds. These findings highlight the potential of the A-site cation substitution strategy for the exploration of new nonlinear optical (NLO) crystals in the short-wave UV range.

Achieving a delicate balance among the short UV cutoff edge (λUV), strong second harmonic generation (SHG) response, appropriate birefringence (Δn), and favorable growth habits has always been a major challenge in the development of ultraviolet (UV) nonlinear optical (NLO) materials. Herein, the highly polar [H2PO3]- group was utilized to induce an ordered arrangement of the planar triangle π-conjugate [C(NH2)3]+, [C(NH2)3]H2PO3 has been successfully designed and synthesized, which exhibits a short UV cutoff edge of 200 nm, a large SHG response of 1.7 × KH2PO4 (KDP), and an appropriate birefringence of 0.117@1064 nm. Furthermore, by replacing [C(NH2)3]+ with a double triangular coupled [C2N4H7O]+ group, another guanylurea phosphite [C2N4H7O]H2PO3 was screened out, which possesses a larger SHG response of 3.5 × KDP, a larger birefringence of 0.155@1064 nm, and a short λUV of 215 nm. Theoretical calculations revealed that their optical performance originates from the synergistic effect of the π-conjugated groups and [H2PO3]-. More importantly, centimeter-sized crystals of both compounds were successfully obtained from the aqueous solution. These results highlight their potential as short-wave UV NLO crystals, offering new insights for the design of novel NLO materials.

Balancing a short ultraviolet (UV) cutoff edge, a sufficient birefringence, and a strong second-harmonic generation (SHG) response is crucial yet challenging in the quest for beryllium-free deep-UV nonlinear optical (NLO) crystals. Herein, we present the synthesis of an optimized KBe2BO3F2 (KBBF)-like fluorinated borate crystal, Rb3Sr3Li2Al4B6O20F (RSLABOF), through a chemical substitution strategy achieved by substituting Be2+ cations in the KBBF structure with Al3+ and Li+ cations. RSALBOF crystallizes in R32 (No. 155), inheriting the structural merits of KBBF and achieving a well-balanced property, including a strong SHG efficiency equivalent to 1.4 times that of KDP, a short UV absorption cutoff edge (<200 nm), and a favorable birefringence value of 0.064 at 1064 nm. Moreover, the layered structure of RSLABOF features a reinforced interlayer bonding facilitated by Sr-O bonds, which is approximately 4.7 times stronger than that in KBBF, alleviating the propensity for layering growth. Theoretical calculations revealed that the significant SHG intensity primarily originates from the in-layer uniformly aligned [BO3] groups in RSLABOF. These observations highlight the potential of RSLABOF crystals as beryllium-free short-wave UV NLO crystals.

ContextThe morphology of logged areas (MLA) can impact medium and large mammal habitat. Assessing MLAs with landscape metrics facilitates sustainable forest management and biodiversity conservation.ObjectivesWe quantified MLAs and assessed their impacts on medium and large mammals.MethodsWe assessed mammal occurrence using camera traps in 24 logged and 26 unlogged sites in South Korea and collected environmental variables, including nine MLA indices, at the microscale (50 m), mesoscale (500 m), and macroscale (1 km). After performing a principal component analysis (PCA), linear mixed and single-species occupancy models were used to assess the effects of principal components on mammal diversity and species-specific responses.ResultsIn the PCA results, MLA components were notably associated with spatial scales, with 50-m-scale indices separated from larger-scale indices. Several MLA components showed strong associations. Microscale MLA traits, particularly edge complexity and reduced unlogged patch connectivity, negatively affected diversity. At the species level, omnivores—specifically, wild boar (Sus scrofa) and Asian badger (Meles leucurus)—were negatively influenced by the same MLA component influencing diversity. In contrast, leopard cats (Prionailurus bengalensis) showed a preference for simplified spatial arrangements—characterized by fewer logged areas and short edges—at the 500 m and 1 km scales.ConclusionsOur findings highlight the importance of MLAs in mitigating logging impacts on mammals, as some morphologies can reduce exposure and provide more favorable habitat. Designing logged areas based on MLA indices can help balance conservation and resource use.

Two new acentric borates, Li2Sr0.5[B3(BO3)4] (1) and Na4[Al3(BO3)4]·Cl (2), with cage-like frameworks constructed by BO3 and TO4 (T = B (1), Al (2)) units, were hydrothermally synthesized. The 3D anionic frameworks of 1 and 2 are built by two types of isostructural B-O and Al-B-O cages, respectively, and are further interpenetrated by polyhedral cubic unit (pcu) cationic frameworks. Both compounds not only feature novel interpenetrating pcu anionic and cationic frameworks, which are rarely observed in borate structural chemistry, but also exhibit moderate second harmonic generation (SHG) responses and a short cutoff edge, indicating their potential as deep ultraviolet nonlinear optical (NLO) crystals.

Alkali metal borogermanates have emerged as promising candidates for ultraviolet (UV) and deep-ultraviolet (DUV) nonlinear optical (NLO) crystals due to their excellent comprehensive performance of a short absorption edge and moderate second harmonic response in the UV regions. A new DUV borogermanate KRb3B6Ge3O17 (KRBG) has been successfully synthesized by a high-temperature solid-state method using a boron-rich B/Ge molar ratio of 2:1. KBRG has a noncentrosymmetric structure and crystallizes in the polar space group Cc. The structure consists of two-dimensional (2D) infinite layers formed by the interconnection and coplanar arrangement of the [B3O8] groups and [GeO4] tetrahedra. The layers are alternately connected by isolated [GeO4] tetrahedra bridging and [GeO4] tetrahedra sharing O atom connections, effectively eliminating the dangling bonds of [B3O8] units and shifting the UV cutoff edge to the DUV region. Experimental and theoretical calculations show that KRBG has a DUV cutoff edge (λcutoff < 200 nm), a large bandgap (6.11 eV), and a moderate second harmonic generation (SHG) effect (1.1 × KDP). The above findings reveal that KRBG is a highly potential NLO crystal in UV and even DUV regions, enriching the structural variety of borogermanate.