CrystEngComm最新文献

Basal and prismatic slips induced by thermoelastic stresses during the growth of 4H-SiC are investigated by using the finite element method (FEM) and considering factors such as the crystal diameter, temperature, and off-axis angle. It is found that with the increase of the crystal diameter from 6 to 8 inches, the prismatic slip more likely occurs, leading to a higher density of basal plane dislocations (BPDs). However, the basal slip hardly changes. The temperature difference, rather than the growth temperature, is the primary factor contributing to the increase in the slip stresses. The stresses of the basal slip are significantly affected by a small off-axis angle, whereas those of the prismatic slip are not unaffected until the off-axis angle reaches 30 degrees. The mechanism for the decrease of the density of BPDs along the growth direction in an 8 inch 4H-SiC crystal is elucidated. We verify that the prismatic slip in an 8 inch 4H-SiC crystal contributes more to the BPD formation than the basal slip.

A novel neptunyl(VI) phosphate compound, (NpO₂)₃(PO₄)₂(Terpy), was synthesized by hydrothermal reaction. It crystallizes in the orthorhombic space group Pca2₁ with unit-cell parameters a = 13.9944 Å, b = 12.1989 Å, c = 13.1277 Å, V = 2241.1 ų, and Z = 4. Related to the layered structure of the uranophane topology, it contains the first reported (Np^VIO₂)₂(PO₄)₂²⁻ sheets, which are bonded via π–π interactions between the Np^VIO₂(Terpy)²⁺ ligands that are perpendicular to the sheets.

In order to prepare polylactic acid (PLA) foam material with excellent performance by utilizing nitrogen (N₂), the crystallization behavior of PLA under N₂ needs to be urgently studied. This article in situ investigated for the first time the impact of N₂ on the crystallization kinetics of PLA. Meanwhile, the influence of N₂ on the crystal structure and crystallization process of PLA was studied. Research has shown that at different crystallization temperatures and N₂ pressures, N₂ exhibited different effects on the crystallization kinetics and crystal structure of PLA. At low crystallization temperature and N₂ pressure, N₂ promoted the growth of PLA spherulites. As the crystallization temperature increases, the maximum N₂ pressure that could accelerate the spherulite growth rate of PLA was also higher. Furthermore, under experimental pressure, N₂ would cause more α′ crystals to form in PLA at low crystallization temperatures. At high crystallization temperatures, the N₂ pressure showed much less impact on the crystalline structure of PLA than that of temperature. In addition, N₂ inhibited the cold crystallization of PLA, reducing the crystallization temperature range and cold crystallization enthalpy.

ZnS/WO₃ composite nanoplates were created by a hydrothermal vulcanization reaction using ZnO as the sacrificial layer. ZnO films were deposited on the surface of WO₃ nanoplates with different sputtering times to act as templates for the hydrothermal synthesis of ZnS/WO₃ nanoplates with different ZnS contents. Structural analysis revealed the sputtering time of the ZnO sacrificial shell layer affected the surface morphology and crystal defects of the ZnS/WO₃ composite materials. The formation of tight heterojunction interfaces and an appropriate number of heterojunctions enhanced the transport of charge carriers, resulting in improved photocatalytic efficiency. Compared to pristine WO₃ nanoplates, the ZnS/WO₃ (WZS) series composite materials showed superior photoelectrochemical properties. The WZS350 composite sample with 3.1 at% Zn and 3.3 at% S was identified as the best photocatalyst. The experimental results of this study demonstrate that WO₃ nanoplates with appropriate ZnS particle modification can effectively regulate their surface photosensitivity, offering a promising approach for the application of photocatalysts.

Numerical simulations are frequently utilized to investigate and optimize the complex and hardly in situ examinable Physical Vapor Transport (PVT) method for SiC single crystal growth. Since various process and quality-related aspects, including growth rate and defect formation, are strongly influenced by the thermal field, accurately incorporating temperature-influencing factors is essential for developing a reliable simulation model. Particularly, the physical material properties of the furnace components are critical, yet they are often poorly characterized or even unknown. Furthermore, these properties can be different for each furnace run due to production-related variations, degradation at high process temperatures and exposure to SiC gas species. To address this issue, the present study introduces a framework for efficient investigation and calibration of the material properties of the PVT simulation by leveraging machine learning algorithms to create a surrogate model, able to substitute the computationally expensive simulation. The applied framework includes active learning, sensitivity analysis, material parameter calibration, and uncertainty analysis.

Ordered porous materials can offer more accessible catalytic sites and large buffer space for discharge products, thus improving cell performance. In this paper, a simple down-top solution-precipitation method followed by pyrolysis was proposed to disperse active nickel–cobalt-NC sites in ZIF-derived porous carbon nanocages. It was found that these metal nanoparticles were confined in the N-enriched carbon nanocage with a total metal loading of about 8.74 at%. As expected, this porous structure not only enhances electron conductivity, but also provides a sufficient surface area to facilitate the triphasic cell reaction and create more space for the storage of discharge products. Experimental findings confirm that this interesting nanostructure manifests an increase in capacity (6682.6 mA h g⁻¹), coulombic efficiency (∼100%) and cycling performance (∼80 cycles) over the control group for quasi-solid-state cells. Benefitting from the addition of Ni to modify the porous structure, the O₂/ion diffusion pathway and accessible active sites are enriched, yielding faster redox kinetics and lower overpotential (high reversibility). Thus, our work demonstrates that this type of porous bimetallic nanocage is promising for fabricating efficient biomass quasi-solid-state Li–O₂ batteries.

High saturation and high stability are two issues that must be addressed in the practical application of structural color based on the self-assembly of colloidal microspheres. Herein, we coated SiO₂ microspheres with island-like polypyrrole (PPy), a black substance that can absorb incoherent scattered light, thereby enhancing the saturation of structural colors on both black and white substrates. Besides, the irregular island-like structure prompts the SiO₂@PPy microspheres to form a short-range ordered amorphous structure, exhibiting non-iridescent structural colors. Importantly, we propose a melt-curing strategy that can enhance the interaction forces between the two microspheres and between the microspheres and the substrate, thus enabling the structural colors to exhibit good stability. Even after rubbing, folding, and ultrasonic cleaning tests, the color of the cured sample remains virtually unchanged. The SiO₂@PPy microspheres prepared and the melt curing strategy in this work can lay foundations for the practical application of structural colors.

The synthesis of novel polyoxovanadates (POVs) has received considerable critical attention. Herein, two new POVs, {V₁₂P₈} (1) and {V₁₆P₈} (2), have been designed and synthesized based on phenylphosphonic acid (PhPO₃H₂) under solvothermal conditions. The structure of 2 is a 16-nuclearity POV composed of four rare zigzag {V₄} secondary building units (SBUs). To the best of our knowledge, 2 is the first POV synthesized with PhPO₃H₂ including this zigzag SBU, which is also very rare among all POVs. Moreover, 2 is the highest-nuclearity isopolyoxovanadate (IPOV) synthesized using PhPO₃H₂ as the only organic ligand so far. The photocatalytic properties of 1 and 2 were studied under visible light. Both 1 and 2 demonstrate good performance in photocatalytic oxidation of 1,5-dihydroxynaphthalene (1,5-DHN). Compound 1 also has a photocatalytic effect on MB degradation, with 87% of MB degradation within 8 minutes.

Carbon nitride is a promising photocatalyst for hydrogen peroxide (H₂O₂) production under visible light irradiation. However, current carbon nitride-based photocatalysts show limited H₂O₂ production owing to high impedance and poor charge transfer ability. In this work, we present a series of CuO decorated graphitic phase carbon nitride (g-C₃N₄) composites, exhibiting suitable bandgaps for the photocatalytic production of H₂O₂. The experimental results showed that CuO/g-C₃N₄ composites exhibited excellent photocatalytic H₂O₂ production performance and good photocatalytic cycle stability. Significantly, the optimized 30%-CuO/g-C₃N₄ composite exhibits a high H₂O₂ yield of 2722.47 μmol L⁻¹ with the addition of CH₃OH under visible light. Furthermore, the photocatalytic mechanism is well studied by density functional theory calculations. This work demonstrates that CuO/g-C₃N₄ composites hold great promise for photocatalytic H₂O₂ production application.

In this work, two fluorescent Cd(II)-based metal–organic frameworks (MOFs), named [CdL(dpa)]·2.5H₂O (1) and Cd₂L₂(2,2′-bpy)₂ (2) (H₂L = 5-[(dimethylamino)thioxomethoxy]-1,3-benzenedicarboxylic acid, dpa = 4,4′-dipyridylamine and 2,2′-bpy = 2,2′-bipyridine), were successfully exploited as fluorescent sensors for the detection of Fe³⁺ in an aqueous medium. Compound 1 was assembled with Cd²⁺, L²⁻ and dpa to construct a porous two-dimensional layer. The (dimethylamino)thioxomethoxy groups in the layer protrude into the adjacent layers to form an interdigitated motif. Compound 2 exhibited an infinite ladder-like chain with the (dimethylamino)thioxomethoxy groups hanging on the two sides of the chain. Fluorescence studies revealed that both 1 and 2 can effectively detect Fe³⁺ in H₂O through luminescence quenching (K_sv = 2.96 × 10⁴ M⁻¹ and LOD = 6.40 × 10⁻⁵ mM for 1; K_sv = 3.31 × 10⁴ M⁻¹ and LOD = 7.65 × 10⁻⁵ mM for 2). The synergistic competitive absorption and coordination interaction mechanism could explain the detection of Fe³⁺. Furthermore, the enlarged steric hindrance in compound 1 resulted in lower values of K_sv and LOD than those of compound 2, which impeded the coordination of Fe³⁺ with its N, O and S recognition sites.