CrystEngComm最新文献

The low reaction kinetics and unstable structure of vanadium-based cathodes often lead to the poor capacity and stability of aqueous zinc-ion batteries (AZIBs). In this study, K⁺ was introduced to regulate vanadium oxide, and novel triple-phase heterostructures were obtained via a solid reaction process. Owing to the large interlayer spacing of potassium vanadate and the sufficient phase boundary in heterointerfaces, Zn²⁺-transport ability in the composites could be effectively increased, and more Zn²⁺-storage sites could be provided in the heterointerface. The cathode materials illustrated an excellent specific capacity of 460.6 mA h g⁻¹ at 0.2 A g⁻¹, comparative rate performance and a capacity retention of 90.7% after 2500 cycles at 3 A g⁻¹. Finally, Zn²⁺- and proton H⁺-storage mechanisms were investigated using ex situ XRD, SEM and XPS analyses. This study proposes a new strategy for the development of high-performance AZIBs.

In recent years, energetic metal–organic frameworks (E-MOFs) have attracted considerable attention as a pivotal strategy for reconciling the inherent trade-off between energy and sensitivity in energetic materials, thereby enhancing their practical applications. This study involves the design and synthesis of a series of novel E-MOFs derived from the N-rich energetic material ATDT and various alkali metals, ranging from ATDT-Li to ATDT-Cs. Research findings indicate that as atomic mass increases, detonation performance initially improves before declining, with ATDT-Na exhibiting the highest performance, surpassing RDX with a detonation velocity of 8897 m s⁻¹ and mechanical stability over 40 J. Furthermore, the results demonstrate that the factors of aromaticity, coordination interactions, and non-covalent interactions significantly contribute to the formation of stable E-MOFs, offering valuable insights for the future development of high-performance E-MOFs.

This study introduces a rapid and non-destructive impurity characterization method using UV absorption spectroscopy that is calibrated against secondary ion mass spectrometry (SIMS) data. A random forest regression model was evaluated for carbon, oxygen, and silicon impurity prediction based on absorption spectra. AlN boules were grown using the seeded PVT method with tungsten crucibles, processed into wafers, and characterized. A matrix of 37 samples with varying impurity concentrations in the range 1 × 10¹⁷ to 5 × 10¹⁹ cm⁻³ was created using element-specific doping methods. SIMS and absorption spectroscopy data revealed characteristic absorption patterns for different impurities. Absorption at 230 nm, which is a crucial wavelength for UVC-LEDs, correlated well with the overall impurity concentration. The random forest model predicted impurity concentrations accurately when similar training data were available, but high prediction errors occurred for unique impurity profiles. To improve prediction accuracy, a more extensive sample series and/or more complex AI tools are required.

Structural regulation of crystal structures to achieve specific structural architectures and/or desired functionalities is one of the main focuses in the field of molecular magnetism. The reaction of a trigonal tetradentate ligand, [TpFe^III(CN)₃]⁻ bridging unit and cobalt metal centres by the altering change of chemical stoichiometry afforded three different structures [{TpFe(CN)₃}₂Co(PyPz₃)]·4MeOH·5H₂O (1), [{TpFe(CN)₃}Co(PyPz₃)]₂(ClO₄)₂·2MeCN·2H₂O (2) and {(Tp)Fe(CN)₃Co(PyPz₃)}_n(BF₄)_n·2nMeOH (3) (PyPz₃ = 2-(di(1H-pyrazol-1-yl)methyl)-6-(1H-pyrazol-1-yl)pyridine and [TpFe^III(CN)₃]⁻ = tri(pyrazolyl)boratetricyanoiron(III)). Detailed structural studies reveal a gradual transformation among the complexes, from a trinuclear structure in 1, to a tetranuclear geometry in 2, and finally to a one-dimensional chain in 3. Magnetic susceptibility measurements revealed that all three complexes exhibit ferromagnetic interactions between the cyanide bridged Fe^III and Co^II centres, with exchange coupling constants of +7.89, +4.37, and +5.92 cm⁻¹, respectively. Our result demonstrates an effective strategy for targeted assembly of architectures by introducing coordinatively unsaturated ligands, complemented by the cyanide-bridged linkers [Tp^RFe^III(CN)₃]⁻.

GaN crystals were grown on MOCVD-GaN films using the Na-flux liquid-phase epitaxial method with a new flux-excess aid technology. The impact of Na : Ga ratio variation on crystal growth under stable melt conditions was investigated. As the Ga content increased, the surface morphology of GaN crystals tended to become flatter. At Na : Ga ratios of 80 : 20, 70 : 30, and 60 : 40, the as-grown GaN crystal thicknesses were 810 μm, 1500 μm, and 530 μm, respectively, with the XRC-FWHM of the (0002) plane of 4100 arcsec, 344 arcsec, and 349 arcsec, respectively. Simulations calculated the distribution of the N ion concentration on the seed crystal surface at the onset of growth under different Ga contents, showing a pattern of lower concentrations in the central region and higher at the edges, with the central region being similar but the edge region decreasing with the Ga content rising. A higher concentration of nitrogen ions can degrade the quality of the crystal, while a lower concentration can reduce the epitaxial thickness. Therefore, with mitigating volatilization of Na, the starting Na : Ga ratio conducive to the growth of high-quality crystals is 70 : 30.

A series of R-[1,2,5]oxadiazolo[3,4-c]cinnoline 5-mono- and 1,5-dioxides containing substituents (R = CH₃, F, Br, CF₃) at different positions were synthesized by an N-nitration–annulation process occurring upon treatment of 3-amino-4-(R-aryl)furazans and 4-amino-3-(R-aryl)furoxans with the HNO₃–H₂SO₄–Ac₂O system. The regioselectivity of the ring closure step was determined for the unsymmetrically substituted R-aryl precursors. Unexpected acylation at position 6 of 7-bromo-[1,2,5]oxadiazolo[3,4-c]cinnoline 5-oxide occurred as a result of the increased duration of the synthesis. The crystal structures of five new compounds were determined by X-ray diffraction analysis, and their crystal packings were compared with each other and with those of previously studied molecules, revealing common motifs regardless of the type or position of the substituent. Specifically, the fluorine derivative forms layers isostructural with those in unsubstituted mono- and dioxides, differing only in their arrangement within the P2₁ and P2₁/c space groups. Two methyl derivatives, on the other hand, exhibit a structure with flat layers. While the crystal environments of different R-substituents are generally distinct, the unsubstituted part of the heterocyclic core tends to form repeating isostructural motifs, such as dimers, chains, and layers. Although substituents disrupt the crystal packing, they still allow for the combination of these motifs in different crystal structures.

Two new three-dimensional (3D) cocrystals of trithiocyanuric acid (TTCA) with hexamethylenetetramine (HMTA) have been synthesized and characterized. In the cocrystal, the monolayer structure forms through N–H⋯N hydrogen bonds due to the establishment of recognition between the thioamide moiety and the N-hetero atom and is further enhanced by the in-plane C–H⋯S hydrogen bonds. Simultaneously, the lamellas consist of two layers, which are recognized by lone-pair⋯π interactions between TTCA molecules, and assembled by the out-of-plane C–H⋯S hydrogen bonds in combination with the spatial van der Waals repulsion between HMTA. Then, the π–hole-based recognizing interaction between the HMTA and TTCA in the neighbouring lamellas, which was assisted by multiple adaptive C–H⋯S hydrogen bonds, contributed to the enhancement of 3D directionality, leading to the construction of 3D structures. And the study found that the stacking types between the lamellas could change due to the competing intermolecular interactions and adaptive C–H⋯S hydrogen bonds, yielding the unit cell structures of two different molecular packing parameters. Thus, two 3D structures of cocrystals, the octahedral (Phpm-o) and polyhedral (Phpm-p), are generated. The growth of these cocrystals was systematically evaluated by predicting the BFDH morphology. Moreover, the importance of each type of intermolecular interaction was quantified by Hirshfeld surface analysis, especially the N–H⋯N, C–H⋯S, etc. Combined with Hirshfeld analysis, the important role of non-covalent forces in the construction of 3D structures was confirmed.

Environmentally friendly graphene-based aerogels have been utilized to recycle leaked organic solvents that pose a threat to the ecological environment. A two-step reduction process assisted by a microbubble technology is developed herein, enabling the successful preparation of an ultralight graphene aerogel (8.13 mg cm⁻³, and 99.63% porosity) with a honeycombed structure. Additionally, the introduction of 2,2-dimethyl-3-methylenenorbornane in the preparation process imparts superelasticity, allowing the aerogel to recover to nearly its original height after 20 axial compression cycles at a maximum strain of 90%. The subsequent annealing process further enhances the hydrophobicity of the graphene aerogel, resulting in a water contact angle of approximately 116°. Its absorption capacities for various organic solvents range from 73.01 to 140.18 g g⁻¹, and it achieves the absorption saturation in about 4 seconds for most organic solvents, demonstrating excellent absorption efficiency. Its superelasticity also enables its reusability through absorption–extrusion and absorption–combustion cyclic measurements. This study offers a novel method to prepare superelastic and ultralight graphene aerogel for efficient absorption of organic solvents for environmental protection.

The rare-earth oxyborate crystal RCa₄O(BO₃)₃ (RCOB, R: rare-earth elements) is an inorganic photoelectric multifunctional material, which has important applications in the field of high-temperature piezoelectricity. In this work, a EuCa₄O(BO₃)₃ (EuCOB) crystal with a diameter of 25 mm was successfully grown by the Bridgman method. The thermal conductivity, thermal diffusivity and specific heat of the EuCOB crystal at high temperature were measured. The dielectric coefficient, electromechanical coupling coefficient, elastic coefficient and piezoelectric coefficient of the EuCOB crystal at high temperature were measured by the resonance–antiresonance method. In particular, the shear piezoelectric coefficient d₂₆ of the EuCOB crystal is 7.01 pC N⁻¹ at room temperature and 6.22 pC N⁻¹ at 800 °C, with a small variation of 11.4%. The electrical resistivities of the EuCOB crystal along the X, Y and Z directions at 800 °C are 5.8 × 10⁷ Ω cm, 3.1 × 10⁷ Ω cm and 2.9 × 10⁷ Ω cm, respectively. The large piezoelectric coefficient and high electrical resistivity indicate the potential application of the EuCOB crystal in a high-temperature piezoelectric field.

This study investigates low-dimensional materials as a potential solution for the miniaturization of electronic devices, addressing the challenges posed by bulk materials. Our research successfully synthesized high-quality V₂PS₁₀ crystals using the chemical vapor transport method and confirmed their dispersibility in various solvents and their potential for mechanical exfoliation. In addition, a UV-sensing device was fabricated to evaluate its performance. In particular, at a wavelength of 254 nm, the fabricated V₂PS₁₀-based UV sensor exhibited a stable response current of 1.5 pA, demonstrating rapid response characteristics. These results underscore the importance of stable synthesis techniques and highlight the potential of V₂PS₁₀ as a one-dimensional UV-sensing material, thereby indicating its applicability to miniaturize electronic components.