ABSTRACT Infrared nonlinear optical (NLO) materials are essential for laser and photonic technologies, limited by fragmented material systems, lengthy development cycles, and trial‐and‐error synthesis. To overcome these barriers, we developed an integrated computational‐experimental framework integrating first‐principles high‐throughput calculations, machine learning, and targeted synthesis. We establish a multidimensional properties dataset of 1807 non‐centrosymmetric compounds and define a comprehensive figure of merit (CFOM) Q based on the statistical average of this dataset to quantify performance trade‐offs. Multidimensional statistical analysis uncovers composition–structure–performance relationships, and reveals superior structure and chemical compositions governing enhanced NLO performance. A Q ‐based crystal graph neural network classifier is developed, achieving strong predictive accuracy (AUC = 0.95). We identify 12 unreported candidates ( Q > 2) from 5105 compounds combining high‐throughput calculation and machine learning. Experiments confirm that defect‐chalcopyrite HgAl 2 Q 4 ( Q = S, Se, Te) shows wide band gaps (1. 55–2.82 eV), suitable birefringence (0.06–0.08), and strong NLO responses (2.2–5 × AGS). This work provides an effective pathway for accelerating the discovery of high‐performance optoelectronic materials.

Infrared nonlinear optical(IR-NLO)crystals are core components for laser frequency conversion,playing a vital role in a range of pivotal technological areas,such as quantum entanglement sources,terahertz wave generation,biomedical imaging and sensing[1,2].However,currently commercialized IR-NLO crystals like AgGaS2(AGS),AgGaSe2(AGSe)and ZnGeP2(ZGP),exhibit some drawbacks such as phase mis-matching,low laser-induced damage threshold(LIDT)and two-photon absorption(TPA)of the conventional 1-2 μm pumping source,which limit their applications in high-power application scenarios[3,4].The underlying challenge stems from an inherent trade-off among material performance parameters:the crystal exhibiting strong second-order NLO effect usually has a small band gap(Eg),generally leading to a low LIDT[5].Consequently,exploring and developing novel IR-NLO materials that can overcome this"performance trade-off"has become a critical scientific challenge and a forefront research direction in this field.

With the advancement of laser technology, there is an urgent need to develop ultraviolet (UV) nonlinear optical (NLO) crystals with balanced performance. To simultaneously achieve a large bandgap, an appropriate birefringence, and a strong second harmonic generation (SHG) response, the [NH2(CH2COOH)2]+ cation is selected as the functional building unit (FBU), leveraging its hybrid structure composed of both pi-conjugated and non-pi-conjugated moieties. The (H2PO3)- and (H2PO2)-, featuring different numbers of hydrogen-bond donors and acceptors, are selected as the direction-guiding components to modulate the arrangement of the organic cations, promoting a preferential alignment. Accordingly, two novel organic-inorganic hybrid compounds-[NH2(CH2COOH)2]H2PO2 (IDAHPO) and [NH2(CH2COOH)2]H2PO3 (IDAPO) are successfully synthesized. Among them, IDAHPO demonstrates a well-balanced NLO property, including enhanced SHG response (1.2 x KDP and 0.13 x beta-BBO), appropriate birefringence (Delta n = 0.118 @ 546 nm), and a short UV cut-off edge (208 nm). This combination of properties enables the material to achieve phase-matched SHG output of 266 nm, a critical and highly sought-after laser wavelength. This strategy establishes a novel approach for the rational design and synthesis of UV NLO materials.

Due to the amplification of climate change in the polar regions, the changes in discharge are more pronounced for the Arctic rivers, which are relevant to other hydro-climatic indicators (e.g., precipitation, snowmelt, groundwater, and permafrost) in the river basin. To investigate the recent changes of river discharge in the Mackenzie River Basin (MRB) responding to climate change, this study used the Mann-Kendall trend test and correlation coefficient approach to examine the long-term variability in discharge at three gauges along the watercourses of MRB between 1972 and 2020, focusing on the inter-decadal trends and the occurrence of hydrological extremes. From the 1970s to 2000s, the discharge in the MRB has increased significantly. However, a reverse trend was shown in the 2010s that is more pronounced in winter and spring. Moreover, the analyses in annual discharge have revealed that the extremely low discharge in 1994/1995 is highly associated with the changes in snowfall, while the extremely high discharge events in 2012/13 and 2019/2020 are more influenced by the reduced sea ice extent and peatland burning over the last decades.

Infrared nonlinear optical materials (IR NLO) have shown important and useful applications in industries and science research. Transition-metal (TM)-based chalcogenides have diverse coordination and broad transparent windows, which make them excellent candidates for IR NLO crystals. However, III-VIB TM-based chalcogenides have been little explored as IR NLO materials. Herein, a first-principles high-throughput screening pipeline (FHSP) has been used for searching promising IR NLO materials in III-VIB TM-based chalcogenides. 89 known TM-based chalcogenides have been selected from 330 noncentrosymmetric (NCS) materials included in the Inorganic Crystal Structure Database (ICSD), which have been systematically surveyed for further investigation. Finally, we successfully synthesized two materials Na3VS4 and CuScS2 with superior predicted performances. The results show that Na3VS4 owns balanced properties, such as giant SHG response (4.19 x AGS), reasonable band gap (2.18 eV), suitable birefringence (0.03 @1064 nm), and long shortest IR absorption (abs.) mode (21.7 mu m). CuScS2 has no obvious vibration absorption peak in the region of 4000-400 cm-1 (2.5-25 mu m) and exhibits moderate SHG response (1.44 x AGS). In addition, this work will afford an orientation to discover more crystal materials.

Nonlinear optical (NLO) materials that can achieve frequency conversion and coherent light emission have garnered significant interest owing to their promising applications in laser technology and advanced photonic systems. In this study, the first-principles high-throughput screening pipeline (FHSP) was employed to systematically explore nonlinear optical materials within vanadate-based systems. A total of 204 vanadates were calculated in the Inorganic Crystal Structure Database (ICSD). Eventually, BiCa2VO6 was screened out and synthesized by a traditional high-temperature solid-state method. BiCa2VO6 exhibits an outstanding second harmonic generation (SHG) response (11.2 × KDP@1064 nm and 1.67 × AGS@2.09 μm), a wide band gap (3.25 eV), and a suitable birefringence (0.123@1064 nm). The work provides a complete perspective for vanadate as a nonlinear optical material and serves as a valuable reference for future research.

The exploration of crystal materials for optical manipulation by nonlinear optical (NLO) and anisotropic light-matter interaction is of paramount importance in modern science and technology. However, in such crystal materials, finding the right balance between second harmonic generation (SHG), birefringence, and the bandgap presents a significant challenge. In this contribution, we employ extended octupolar pi-conjugated groups devoid of intrinsic dipole moments to construct melonate-based inorganic-organic hybrid crystals, thereby achieving simultaneous large optical nonlinearity and anisotropy. In accordance with this strategy, Rb3[C6N7(NCN)3]3H2O (I) and Cs3[C6N7(NCN)3]3H2O (II) were obtained and subjected to detailed investigation. Strong SHG responses of similar to 9x KH2PO4 and a large birefringence of at least 0.6@546 nm were observed for I and II crystals, respectively, together with a suitable bandgap for visible-UV application. Theoretical calculations indicated that octupolar [C6N7(NCN)3]3- groups of I and II arranged in a near parallel configuration exhibit a discrete pi electron distribution, resulting in enhanced NLO susceptibilities and maximal polarizability difference. This work underscores the potential of octupolar structures with extended pi-conjugation as a promising avenue for the discovery of NLO and birefringence crystals.

Lanthanide (Ln3+) complexes with organic ligands have recently gained extensive attention due to their unique optical features such as high color purity, narrow and intense emission bands and long excited state lifetimes, showing diverse applications in tunable lasers, optical amplifiers, biomedical diagnosis, high density information storage and so on. However, some inherent shortcomings, such as poor stability (photo-, thermal- and mechanical), low processability and the tendency to aggregate significantly, limit their full exploitation in practical applications. Incorporating of Ln3+ complexes into polymers matrices are effective means to improve their properties and broaden their applications. In recent decades, significant progress has been made in Ln3+ complexes-containing polymers, varying from structural evolution of ligand molecules and polymers to application expansion of luminescent functional polymers. This review will systematically summarize the key points in the synthesis methods (including both physical doping and chemical cross-linking) of Ln3+ complexes-containing polymers. The critical strategies to prepare self-healing luminescent polymers will be discussed in detail. We then review the emerging applications of Ln3+ complexes-containing polymers ranging from light-conversion films, organic light-emitting diodes, bio-imaging to temperature sensing applications. At the end of this review, we will provide an outlook on the opportunities and challenges of Ln3+ complexes-containing polymers.

γ -Bi 2 MoO 6 exhibits a 9.9-times stronger second harmonic generation (SHG) response than that of KDP, large birefringence of 0.21 at 1064 nm, and relatively large band gap of 2.57 eV.

With the advancement of laser technology, searching for new nonlinear optics (NLO) active units is necessary for designing NLO materials with excellent performance. In this study, an amino substitution strategy is proposed to explore new planar pi-conjugated groups as functional building units (FBUs) for NLO and birefringent materials. Accordingly, a new NLO-active molecule melem C6N7(NH2)(3) is identified, which is characterized by significant polarization anisotropies and large hyperpolarizabilities. Subsequently, C6N7(NH2)(3)center dot H3PO4 is screened out and successfully synthesized through a simple aqueous method. The compound exhibits a strong second harmonic generation (SHG) response of 8.9 times that of KDP and a large birefringence of 0.609 at 1064 nm. As far as is known, the calculated birefringence of C6N7(NH2)(3)center dot H3PO4 is the largest among the organic-inorganic hybrid crystals in which the birefringence originates from pi-conjugated groups. The theoretical computation supports that the amino (-NH2) substitution strategy is effective for designing and synthesis of materials with strong SHG response and large birefringence.

Nonlinear optical (NLO) crystals are crucial components in all-solid-state lasers because they expand the wavelengths of existing laser sources through laser frequency conversion. In this work, Ag-2[TeO2(OH)(4)] was identified in tellurates using the first-principles high-throughput screening pipeline for NLO materials (FHSP-NLO). The material was successfully produced via mild aqueous solution synthesis conditions, and a single crystal of 8 x 4 x 4 mm(3) in size was obtained. Ag-2[TeO2(OH)(4)] is one of the few materials that contains the [TeO2(OH)(4)](2-) anionic group and belongs to the non-centrosymmetric (NCS) space group. Ag-2[TeO2(OH)(4)] exhibited balanced comprehensive performances, including a large second harmonic generation (SHG) response of about 0.84 x AgGaS2 (AGS), moderate band gap (2.73 eV) and large birefringence (0.106@1064 nm). First-principles studies revealed that the dominant units that contribute to the crystal's linear and nonlinear optical properties are Ag atoms and TeO2(OH)(4) groups.

AbstractCombining π‐conjugated and non‐π‐conjugated groups is an important strategy for synthesizing new nonlinear optical (NLO) crystals. However, the second harmonic generation (SHG) response and optical anisotropy can be limited by improper spatial alignment of these functional groups in the crystal structure. In this work, it is revealed that non‐π‐conjugated [NH2SO3] group acts as both hydrogen bond donor and acceptor, effectively regulating the 2D planar structure formed by π‐conjugated [C4N3H6] groups. The resulting organic–inorganic hybrid crystal C4N3H6SO3NH2 exhibits a strong SHG response (2.5 × KDP), large optical anisotropy (0.233@546 nm), and blue‐violet and green fluorescence near 360 and 520 nm, respectively. This work expands the methodology for creating new NLO crystals through organic–inorganic hybridization, while also showcasing the potential of C4N3H6SO3NH2 as a multifunctional optical material.

Infrared nonlinear optical (IR NLO) materials play significant roles in laser technology. The novel functional building units (FBUs) are of great importance in constructing NLO materials with strong second harmonic generation (SHG). Herein, polysulfide anion [S-x](2-) (x = 2, 3, 4, 5) units are investigated on NLO-related properties and structure-performance relationships. Theoretical calculations uncover that the [S-x](2-) (x = 2, 3, 4, 5) units are potential IR NLO FBUs with large polarizability anisotropy (delta), hyperpolarizability (beta) and wide HOMO-LUMO gap. Fourteen crystals including [S-x](2)- (x = 2, 3, 4, 5) units are calculated and analyzed. The results show that these units can result in a wide IR transmittance range, significant SHG effects, wide band gap E-g (Na2S4: Eg = 3.09 eV), and large birefringence Delta n [BaS3 (P2(1)2(1)2): Delta n = 0.70]. More importantly, it is highlighted that the crystal materials including with [S-x](2-) (x = 2, 3, 4, 5) groups are good candidates for the exploration of the outstanding IR NLO materials.

Investigation of photoluminescence (PL) and fracture-induced triboluminescence (TL) is necessary for the development of both fundamental theories and practical applications in mechanical energy conversion; however, most known PL/TL-emitting materials are confined to inorganic systems. In this study, a novel lanthanide-based crystalline complex (LnCC), Eu(DBM)3DETA was synthesized via the synergistic coordination of Eu3+ with DBM (Dibenzoylmethane) and DETA (Diethylenetriamine) units, leading to the formation of brighter LnCC with bright red emission, high PL quantum yields (57.19 %) and unique TL characteristics. The key to success in obtaining Eu (DBM)3DETA is the utilization of DETA molecule as synergistic ligand, presenting block crystals with higher coordination number of Eu3+ ions via recrystallization. Due to the dense accumulation of cross-linked threedimensional frameworks through van der Waals interactions, the fracture-induced piezoelectric effect results in charge separation and excitation through the resultant electric field and discharge, triggering a fast TL response of Eu(DBM)3DETA and expanding the possibilities of the quantitative stress sensing. Importantly, amorphous powders can still recover to their original PL and TL emission intensities after recrystallization in cyclic crystalto-amorphous phase transitions. The unique PL and TL characteristics of Eu(DBM)3DETA provide promising opportunities to display stress visualization differences of electronic signatures under different forces.

Ground freeze‒thaw processes have significant impacts on infiltration, runoff and evapotranspiration. However, there are still critical knowledge gaps in understanding of hydrological processes in permafrost regions, especially of the interactions among permafrost, ecology, and hydrology. In this study, an alpine permafrost basin on the northeastern Qinghai‒Tibet Plateau was selected to conduct hydrological and meteorological observations. We analyzed the annual variations in runoff, precipitation, evapotranspiration, and changes in water storage, as well as the mechanisms for runoff generation in the basin from May 2014 to December 2015. The annual flow curve in the basin exhibited peaks both in spring and autumn floods. The high ratio of evapotranspiration to annual precipitation (>1.0) in the investigated wetland is mainly due to the considerably underestimated ‘observed’ precipitation caused by the wind-induced instrumental error and the neglect of snow sublimation. The stream flow from early May to late October probably came from the lateral discharge of subsurface flow in alpine wetlands. This study can provide data support and validation for hydrological model simulation and prediction, as well as water resource assessment, in the upper Yellow River Basin, especially for the headwater area. The results also provide case support for permafrost hydrology modeling in ungauged or poorly gauged watersheds in the High Mountain Asia.

Smart luminescent materials that have the ability to reversibly adapt to external environmental stimuli and possess a wide range of responses are continually emerging, which place higher demands on the means of regulation and response sites. Here, europium ions (Eu3+)-directed supramolecular metallogels are constructed by orthogonal self-assembly of Eu3+ based coordination interactions and hydrogen bonding. A new organic ligand (L) is synthesized, consisting of crown ethers and two flexible amide bonds-linked 1,10-phenanthroline moieties to coordinate with Eu3+. Synergistic intermolecular hydrogen bonding in L and Eu3+-L coordination bonding enable Eu3+ and L to self-assemble into shape-persistent 3D coordination metallogels in MeOH solution. The key to success is the utilization of crown ethers, playing dual roles of acting both as building blocks to build L with C2-symmetrical structure, and as the ideal monomer for increasing the energy transfer from L to Eu3+'s excited state, thus maintaining the excellent luminescence of metallogels. Interestingly, such assemblies show K+, pH, F-, and mechano-induced reversible gel-sol transitions and tunable luminescence properties. Above findings are useful in the studies of molecular switches, dynamic assemblies, and smart luminescent materials.

High-performance nonlinear optical （NLO） crystals are crucial devices to convert wavelength of solid-state lasers.Chalcogenides play an indispensable role in the research of infrared NLO materials. In this work, ternary chalcogenide ZnGa 2 S 4 with defect diamond-like structure was screened out and synthesized by chemical vapor transport method.