Constructing an interfacial optimized heterojunction with plentiful connections and strong electric field interactions is an effective method to promote the efficiency of spatial charge separation and photocatalytic activity. Herein, a 2D/2D WO3/Bi5O7I heterojunction with an S-scheme structure was prepared by a simple calcination method. WO3 nanosheets were uniformly anchored to the surface of porous Bi5O7I nanoplates. The prepared 2D/2D WO3/Bi5O7I heterojunction showed excellent performance and long-term cycling stability in the photocatalytic degradation of tetracycline. In particular, 15% WO3/Bi5O7I exhibited the best tetracycline degradation activity, which was 8.93 and 4.47 times that of pristine WO3 and Bi5O7I, respectively. The enhanced photocatalytic performance is attributed to the intimate interfacial contact between the photocatalysts, resulting in an internal electric field at the 2D/2D WO3/Bi5O7I heterojunction interface. This facilitated the separation and utilization of photo-generated charge carriers, thus suppressing the high recombination rates in Bi5O7I. A possible S-scheme charge transfer pathway is proposed at the interface of the 2D/2D WO3/Bi5O7I heterojunction.

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Two organic ligands, one rigid and one flexible, were designed and used to construct two cobalt-based metal–organic frameworks (MOFs) with coligands to obtain 3D and 2D structures, respectively. Both the Co-based MOFs were pyrolyzed at different temperatures to obtain the derived materials, and their electrocatalytic hydrogen evolution properties were studied. The results show that the electrocatalytic hydrogen evolution performance of MOF derivatives based on the rigid ligand was better than that of MOF derivatives based on the flexible organic ligand.

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Laser induced damage sites on the surface of a KDP crystal component tend to grow with subsequent laser irradiation, which substantially decrease the lifetime of these optics. The structural investigation suggests that this may be related to the surface damage products of the crystals. In this work, the differences in the crystal structures, electronic properties and optical absorption between the KDP crystal and its surface laser-induced decomposition products K2H2P2O7 and KPO3 are investigated by using first-principles calculations. The theoretical results show that the nonlinear optical active units of KDP crystals are disrupted after irradiation dehydration to K2H2P2O7 and KPO3, which leads to the optical properties at the surface damage being deteriorated. In terms of the electronic structure, the dehydration products K2H2P2O7 and KPO3 have a shorter band gap compared with the KDP crystal. In addition, K2H2P2O7 and KPO3 have a wider optical absorption band than that of the KDP crystal and introduce more ultraviolet absorption in the optical elements. Compared to polycrystalline KDP at the bulk damage sites, the dehydration products at the surface damage increase the ultraviolet absorption of the crystals and cause the surface damage to continually grow under subsequent irradiation, whereas the bulk damage does not continue to increase in subsequent laser irradiation.

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Luminescence thermometry has recently been gaining popularity in science and technology fields. However, most reported works have used the fluorescence intensity ratio (FIR) to obtain the temperature based on thermally coupled energy levels (TCLs), which have hindered the sensitivity of the technique and limited its applications. Here, NaYF4:Yb/Tm@NaYF4:Yb/Ho microcrystals were prepared using a hydrothermal method. Based on the non-thermally coupled energy levels (NTCLs) of the double luminescent ionic centers Tm3+ and Ho3+, the materials exhibited temperature-dependent luminescence in the range of 304 K to 574 K. The maximum sensitivities were found to be Sa = 0.135 K−1 at 574 K and Sr = 1.101% K−1 at 484 K based on red (Tm3+) and green (Ho3+) emission bands. This study has provided a promising new strategy to break the TCL restriction and has shown the material to have potential applications in luminescence thermometry.

The uniform incorporation of metal and carbon with nanoporous silicon is highly desirable for improving overall Li-storage performance, yet remains a great challenge owing to the different physicochemical properties of Si, M, and C tri-components. Here, we develop an interpenetrating gel-enabled route for uniformly integrating metal and carbon with nanoporous silicon. Specifically, Co and C dual matrices are simultaneously and homogeneously incorporated with nanoporous silicon by magnesiothermically co-reducing an interpenetrating gel, containing SiO2 gel and cyano-bridged In(III)–Co(III) coordination polymer gel networks. Thanks to the nanoporous structure and uniform M/C hybridization, the Si–Co–C ternary material manifests good cycling life (1837 mA h g−1 after 100 cycles at 0.5 A g−1) and superior rate performance (1318 mA h g−1 at 10 A g−1).

This work explores the magneto–structural relationships and crystal engineering in five copper(II) complexes of formulas [Cu(bpca)(H2L1)]n·n(CH3)2SO·3nH2O (1), [Cu(bpca)(H2L1)]n·3nCH3OH (2), [Cu(bpca){Cu(bpca)(H2L1)}(H2L1)]n·0.5n(CH2OH)2·3.5nH2O (3) and [Cu(bpca){Cu(bpca)(H2L1)}]n(NO3)n·2n(CH2OH)2·nH2O (4) and [{Cu(bpca)}2L2]·2H2O·0.33(CH2OH)2 (5) [Hbpca = bis(2-pyridylcarbonyl)amide, H3L1 = 4-(1H-pyrazole-4-yl)phenylene-N-(oxamic acid) and H2L2 = 4-(1,2-oxazol-4-yl)phenylene-N-(oxamic acid)]. They are constituted by [Cu(bpca)]+ units and two oxamate-based ligands, one of them containing pyrazole substituents (1–4) and the other one an isoxazole group (5). Compounds 1–4 are one-dimensional coordination polymers. 1 and 2 are coordination isomers with different solvates and the first examples of monodentate oxamate ligands. 3 exhibits a novel carboxylate(oxamate) coordination mode in the syn–anti conformation and the oxamate group in 4 lies between the previous coordination modes, adopting a bidentate/monodentate bridging form. They all have the pyrazole group as a probe for molecular recognition, especially recognizing the deprotonated carboxylate portion of the oxamate via hydrogen bonds. The new coordination modes of the oxamate groups in 1–3 result from the presence of pyrazole and the synthesis in different solvent mixtures. 5 is a dicopper(II) complex where the oxamate group exhibits the bis(bidentate) bridging mode. There is no possibility of molecular recognition in 5 because of the lack of hydrogen bond donors and it can be considered as a counterpoint to investigate the results of L1-based complexes. An insight based on crystal engineering concerning the nature of the ligands and their synthetic routes was provided. Cryomagnetic measurements on 1, 3, and 5 in the temperature range 1.9–300 K revealed the occurrence of weak antiferromagnetic interactions [J = −0.86 (1), −0.60 (3) and −1.25 cm−1 (5)]. Orbital overlap considerations based on their crystal structures originating from the different molecular recognition of the pyrazole/isoxazole groups were used to account for these small magnetic couplings.

Y2O3:Eu3+,Tb3+,Ce3+ phosphors were prepared by the co-precipitation method and the optimal component formulations of the samples were determined by a combination of controlled variable method and orthogonal experiments. The experimental results show that doping with appropriate amounts of Tb3+ and Ce3+ significantly improved the luminescence performance of Y2O3:Eu3+ phosphors. In the Y2O3:Eu3+,Tb3+,Ce3+ phosphors system, Tb3+ could be used as a carrier to transfer energy for Ce3+–Eu3+, eliminating the presence of metal–metal charge transfer (MMCT) between the two ions. The direction of energy transfer which is from Ce3+ → Tb3+ → Eu3+ has been confirmed by emission spectrum and calculation results show that the mechanism of Tb3+ to Eu3+ energy transfer and Ce3+ to Tb3+ energy transfer in Y2O3 matrix are both quaternary–quaternary interactions. As the doping concentration of Tb3+ and Ce3+ increases, the emission peak position of phosphor was shifted toward the blue region. Their structure and micromorphology have been analyzed by X-ray diffraction and scanning electron microscopy, the test results show that ion doping does not cause changes in the crystal structure of Y2O3 and the samples are approximately spherical in shape. This work provides a new idea to study the UV detection and multi-ion inter-energy transfer model.

Despite the considerable potential and significant promise of aluminum scandium nitride (AlScN) ferroelectric materials for neuromorphic computing applications, challenges related to device engineering, along with the considerable structural disorder in thin films grown on various substrates using different vapor synthesis methods, make it difficult to systematically study the structure–property relationship. In this work, we approach such issues from the crystal growth side by successfully growing high-quality single crystal AlScN nanowires through ultra-high vacuum reactive sputtering under high substrate bias and low atomic flux conditions, which leads to simultaneous growth and etching. Characterization of nanowire arrays using X-ray diffraction and transmission electron microscopy shows that the wires are epitaxial single crystals with significantly reduced mosaic spread and predominantly single ferroelectric domains. Moreover, ferroelectric and piezoelectric properties were evaluated using Piezoresponse Force Microscopy. The single crystal AlScN nanowires show an out-of-plane piezoelectric constant d33 that is greater than 20 pm V−1, which is higher than that of pure AlN by a factor of ∼4.

The solubility, permeability, and dissolution rate of an active pharmaceutical ingredient (API) are critical factors in determining its pharmacokinetic performance in oral dosage forms. Modifying these properties can potentially enhance the drug's pharmacokinetics. Vandetanib (VDTB), classified as a class II anti-cancer drug in the biopharmaceutical classification system (BCS), suffers from low solubility (0.008 mg mL−1) and an extended pharmacokinetic half-life (19 days), necessitating the administration of high doses, which leads to undesirable side effects. To address this issue, we have employed a crystal engineering approach to enhance the solubility of VDTB. We employed the liquid-assisted grinding (LAG) method followed by the slow evaporation technique to prepare novel solid forms of VDTB by incorporating various aliphatic dicarboxylic acids, including succinic acid (SUA), adipic acid (ADA), pimelic acid (PIA), azelaic acid (AZA), and sebacic acid (SBA). These newly obtained solid forms were characterized by SC-XRD, PXRD, TGA, and DSC experiments. The crystal structure analyses revealed a proton transfer between the carboxylic acid group of aliphatic acids and the N-methyl piperidine moiety of VDTB, confirming salt/adduct formation. Additionally, all of the molecular salts were stabilized by charge-assisted N+–H⋯O− hydrogen bonds, while the parent VDTB crystal structure is stabilised by N–H⋯N interactions. Moreover, the solubility and dissolution rate of these new solid forms were assessed in a pH 7.4 phosphate buffer medium, with the results indicating that all of the solid forms, except for VDTB:SBA, exhibited higher solubility compared to pure VDTB. These findings offer promising prospects for the development of an improved VDTB formulation with enhanced pharmacokinetic properties.

Crystals with elastic and photomechanical properties are rather scarce, but very important. Herein, we report an elastic crystal based on the photo-reactive acylhydrazone derivative (E)-N′-([1,1′-biphenyl]-4-ylmethylene)picolinohydrazide (BPMP). Under ultraviolet (UV) irradiation, the crystal bent away from the UV light. Upon heating, the bent crystal returned to a nearly straight state, demonstrating a reversible bending behavior. The 1H nuclear magnetic resonance (1H NMR) data revealed that the molecules in the crystal underwent reversible E ↔ Z isomerization under light and heating conditions. Applying or withdrawing mechanical forces allowed the crystal to be reversibly bent multiple times, displaying excellent elastic properties. Interestingly, the output direction of 635 nm red light could be controlled by controlling the bending of the crystal through light and mechanical force. Therefore, this work provides new ideas for the design of multifunctional elastic crystals.

High-quality GaN films on nanoscale patterned sapphire substrates (NPSSs) are required for micro-light-emitting diode (micro-LED) display. In this study, two types of nucleation layers (NLs), including in situ low-temperature grown GaN (LT-GaN) and ex situ physical vapour deposition AlN (PVD-AlN), are applied on cone-shaped NPSS. The coalescence process of GaN grains on the NPSS is modulated by adjusting the three-dimensional (3D) growth temperatures. Results show that low 3D temperatures help to suppress the Ostwald ripening of GaN grains on the NPSS, facilitating the uniform distribution of 3D GaN grains. Higher 3D temperatures lead to a decrease in the edge dislocation density, accompanied by an increase in residual compressive stress. Compared with LT-GaN NLs, PVD-AlN NLs can effectively improve the growth uniformity, suppress the tilting and twisting of GaN grains grown on NPSSs, and promote the orientation consistency of crystal facets during coalescence. The GaN films grown on NPSSs with PVD-AlN NLs exhibit a decrease in the coalescence time from 2000 s to 500 s, a reduction in dislocation densities from 2.8 × 108 cm−2 to 1.4 × 108 cm−2, and an increase in the residual compressive stress from 0.98 GPa to 1.41 GPa compared to those grown on LT-GaN NLs. This study elucidates trends in dislocation and stress evolution in GaN films on NPSSs with analysis of grain coalescence.

In the context of the energy crisis, the optimal utilization of clean agricultural waste is of growing significance. This study employs a cost-effective method to obtain high-purity amorphous bio-based silica (RHA-SiO2) from rice husk ash (RHA) post pyrolysis. Leveraging the Taguchi method and response surface method (RSM) for the first time, this research utilizes pyrolysis and torrefaction temperatures as key determinants for the RHA-SiO2 particle size. Through an L36 (22 × 32) orthogonal test, key influencing factors were recognized. Subsequent optimization employed the central composite sequential (CCC) analysis, resulting in an interaction model that was experimentally validated with 96% to 99% accuracy. Such advanced techniques allow for a greater accuracy to be achieved in RHA-SiO2 extraction systems.

NiFe-LDH/g-C3N4 (LDH/CN) heterostructures with different amounts of NiFe-LDH (LDH) were prepared by a hydrothermal method and characterized using different experimental techniques. Their photocatalytic properties were investigated using the degradation of tetracycline hydrochloride (TC) and the production of hydrogen from water splitting. Experimental results showed that the hydrogen production rate (780.5 μmol g−1 h−1) was 2.29 times that of pristine CN, and the TC removal rate (76.3%) of 1.8LDH/CN was 3.71 times that of CN. According to the detailed study of the structural, optical, and photoelectrochemical properties, a type II charge transfer mechanism was proposed to explain the improved photocatalytic performance of LDH/CN.

High-energy solid-state pulsed lasers are used for intriguing applications in various fields and typically require amplification gain media with large dimensions, low pump saturation density, moderate emission saturation flux, and superior energy storage properties. Yb-doped calcium niobium gallium garnet (Yb:CNGG) crystals are promising gain candidates for laser amplification. However, obtaining large-sized crystals is still a challenge due to the deviation of chemical compositions and accompanying chemical stress arising from the intrinsic disordered coordination structure of the crystal. Herein, we report the growth of Yb:CNGG crystals to large sizes by thoroughly managing the influences of raw materials and temperature field. By optimizing the initial chemical composition and temperature gradient distribution, we successfully grew a 60 mm-diameter Yb:CNGG crystal without any cracks. The subsequent results indicated that the as-grown crystal exhibited satisfactory crystallinity (full width of half maximum of 38.02′′), moderate thermal conductivity (3.98 W m−1 K−1), excellent optical uniformity (3.85 × 10−4), a low fluctuation of the Yb doping concentration (±3.57%), and a large laser damage threshold (51.03 J cm−2). Our findings not only provide a promising gain medium for developing high-energy laser amplification systems but also are significant for growing large-sized crystals with disordered coordination structures.

Understanding the relationship between molecular composition/structure and crystal packing is a fundamental challenge in crystal engineering. Planar molecules and planar layer-stacking, as a special group of molecules and a special molecular stacking mode, respectively, occupy special positions in molecular materials. Herein, we constructed two data sets of 1612 planar CHON-containing molecules and a further 65 planar layer-stacked molecules under neither heated nor pressurized conditions, and obtained the composition and structure characteristics thereof. CO and CH molecules do not easily form planar and planar layered structures, respectively. The lowest requirement of the molecular symmetry of plane, Cs, constitutes the largest proportion for both the total planar molecules and the specially planar layer-stacked molecules. In general, high planarity tends to result in planar layer-stacking. Therein, intermolecular hydrogen bonding and the CO group appear frequently to maintain the layers. Still, they are not necessary for the stacking. Additionally, the molecules show packing coefficients (PCs) concentrated within 0.70–0.75, implying a decreasing interlayer distance accompanied by an increasing intralayer intermolecular sparsity. These characteristics of planar and planar layer-stacked CHON-containing molecules are expected to be useful for feature engineering in designing novel molecules.

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