Crystal Research and Technology最新文献

For heteroepitaxial single-crystal diamond growth, iridium is recognized as the optimal nucleation layer due to its unique carbon-saturated precipitation mechanism that facilitates the formation of highly oriented and dense diamond nuclei. This study employed magnetron sputtering to deposit iridium on (11-20) a-plane sapphire substrates, systematically investigating the effects of deposition temperature, sputtering power, and rapid high-temperature annealing on the orientation, surface morphology, and film quality of Ir. Experimental results demonstrated that (100)-oriented Ir films are successfully achieved at a deposition temperature of 780°C with 125 W sputtering power. Subsequent rapid thermal annealing at 1000°C significantly improved the crystalline quality, evidenced by the reduction of FWHM for Ir (002) XRD rocking curve from 436 to 323 arcsec. TEM analysis confirmed the single-crystal nature of Ir films with minimal lattice strain. This achievement of high-quality Ir films establishes a crucial foundation for optimizing the quality of subsequent heteroepitaxial single-crystal diamond growth. The fabrication of high-quality, highly-oriented iridium films serves as an essential prerequisite for the successful nucleation and growth of high-quality heteroepitaxial diamond. This study demonstrates the deposition of Ir on 2-inch sapphire, thereby representing a critical step toward the realization of heteroepitaxial single-crystal diamond at the 2-inch scale and beyond.

To enhance the hygroscopic properties of palmatine chloride (PCl), a novel salt cocrystal is synthesized through the combination of water-assisted grinding and solvent evaporation methods applying p-coumaric acid (CA) as the cocrystal co-formers. Single crystal X-ray analysis revealed that four chloride ions, two water molecules, and two coumaric acid molecules interacted via hydrogen bonding to form the typically basic structural units, which connected through weak interactions to form 2D planar structures in the boc plane. The palmatine molecules are arranged vertically between the planes and continuously stacked to form a 3D crystal structure. In comparison to PCl, the hygroscopic stability of the PCl-CA salt cocrystal is notably improved, indicating that CA molecules occupied the binding site between chloride ions with strong hydration ability and external water molecules in the self-assembly of the salt cocrystal, thus reducing the binding affinity of PCl-CA to water. Although the hygroscopic stability of PCl-CA is considerably enhanced compared to PCl itself, its solubility is regrettably lower, warranting further investigation. Notably, the introduction of CA molecules significantly boosted the antibacterial potency of the PCl-CA salt cocrystal in vitro. The aforementioned experimental outcomes are corroborated by theoretical calculations, encompassing frontier molecular orbitals analysis and Hirshfeld surface analysis.

The DFT study of Alanine Maleate and Alanine Fumarate NLO crystals assisted by B3LYP/6-31+G^* in the gas phase investigates the optimized geometry, Mulliken charges, Frontier Molecular Orbitals (FMO), Hyperpolarizability, and Vibrational spectra of the molecules. The Natural Bond Orbital analysis of Alanine Maleate and Alanine Fumarate sheds light on the hyperconjugative interactions of LP N3 → σ* H5─O25 and LP N3 → σ^* O23─H24, suggesting the existence of the hydrogen bond between N3─H5 and N3─H24, respectively. The analysis of Quantum Theory of Atoms in Molecules (QTAIM) with the help of Multiwfn revealed the type of hydrogen bonding on the basis of topological parameters at the Bond Critical Points. The Reduced Density Gradient study has facilitated a pictorial depiction of the strong hydrogen bonding of N─H and other Non-Covalent Interactions (NCI) present within the molecules. The kinetic stability of the material has been sufficiently indicated by the HOMO-LUMO energy gap. The UV spectra obtained from TD-DFT highlighted the transparency of Alanine Maleate and Alanine Fumarate above 300nm in the UV region, with a cut-off wavelength around 250nm. The Molecular Electrostatic Potential Surface displayed the electrophilic sites of Alanine Maleate and Alanine Fumarate. The theoretically predicted IR and Raman spectra demonstrated the characteristic vibrations of the functional groups, including the N─H hydrogen bonds. The computed first-order Hyperpolarizability value of Alanine Maleate and Alanine Fumarate is 3.9 and 1.64 times that of Urea, quoting its prominent NLO efficiency.

The co-crystallization behavior of the energetic compound 3-nitro-1,2,4-triazol-5-one (NTO) with planar heteroaromatic coformers is examined to assess its impact on molecular interactions and thermal stability. NTO is co-crystallized with 3-aminopyrazole (APRZ), 1,2,4-triazole (TRZ), 4-amino-1,2,4-triazole (ATRZ), and imidazole (IMD) at specific molar ratios in polar protic solvents. The crystalline structures obtained are analyzed through single-crystal X-ray diffraction, nuclear magnetic resonance (NMR) spectroscopy, and infrared (IR) spectroscopy techniques. Thermogravimetric analysis (TG) is used to evaluate the effect on explosive characteristics. Single crystal X-ray diffraction (SCXRD) data demonstrate that the co-crystals displayed unique lattice structures in contrast to the pure components, suggesting notable intermolecular interactions between NTO and the coformers. Structural analysis reveals that planar NTO molecules are organized into layers parallel to the planar configurations of APRZ, TRZ, ATRZ, and IMD. Instead of π–π interactions, it is observed that strong hydrogen bonds between the molecular rings serve as the primary driving force for co-crystal formation. The thermogravimetric analysis reveals that the co-crystals underwent disintegration close to the melting point of NTO, subsequently decomposing and exhibiting thermal behavior characteristic of two distinct substances.

Natural mollusk shells achieve exceptional combinations of hardness and toughness through hierarchically organized architectures. While the structural–mechanical relationships of many nacreous bivalves and conch shells have been studied, the shell of Monetaria annulus remains largely unexplored. Here, we investigate the hierarchical structure, composition, and mechanical performance of Monetaria annulus using an integrated multi-scale characterization approach. The shell exhibits a pronounced mineralization gradient, with outer layers more highly mineralized than inner layers in some regions, and comprises five structurally distinct regions, including stacked and tiled crossed-lamellar layers and an interlocking inner architecture. The fundamental building block of the shell is crystalline aragonite fibers, and the weight fraction of organic substance is ∼2.62%. The distinct crystal orientation of stacked and tiled layers could be clearly distinguished from confocal Raman mapping analysis. While the stacked layers and tiled layers exhibit nearly identical hardness and elastic modulus, tiled layers promote crack branching and microcrack formation. These findings demonstrate that Monetaria annulus achieves damage tolerance through the synergistic integration of mineralization gradients, layer orientation diversity, and nanoscale fiber alignment, offering valuable principles for the design of lightweight, impact-resistant bioinspired materials.

Silicon carbide (SiC), a wide-bandgap semiconductor, exhibits outstanding properties that make it highly suitable for high-performance electronics. Top-seeded solution growth (TSSG) is a promising method for growing high-quality SiC single crystals. This study focuses on the growth of 6-in. 4H-SiC crystals using the TSSG method. Through numerical simulations and experiments, the effects of solution diameter (D = 200–300 mm), seed rotation speed (ω = 50–200 rpm), and relative distance between the crucible and coil (ΔH = 10—40 mm) on crystal growth rate and surface quality are investigated. The results demonstrate that increasing D and ω reduces the growth rate disparity between the center and periphery of the seed crystal, improving surface morphology and eliminating solvent inclusions. A D of 240 mm yields the maximum growth rate, while a larger diameter enhances growth stability. Higher rotation speeds facilitate faster growth rates and promote uniform growth. Increasing ΔH shifts the high-temperature zone position, reducing the overall growth rate, expanding the crystal diameter by 10 mm, which alters the crystal shape from circular to hexagonal. The optimized parameters (D = 270–300 mm, ω = 200 rpm, ΔH < 0) enable controllable growth of 6-in. SiC crystals.

Acipimox is a broad-spectrum long-acting lipid-lowering agent used to treat a variety of primary and secondary hyperlipidemia. However, the poor solubility of acipimox limits its bioavailability. To improve its solubility, acipimox-theophylline dihydrate cocrystal (ATH) is prepared by the traditional solvent evaporation crystallization technique for the first time. ATH is characterized by SEM, Raman, Thermal analysis, and X-ray diffraction. Crystal structure analysis manifests that in ATH, acipimox, theophylline, and two molecules of water interact and pack to form a stable 1D tubular structure primarily through hydrogen bonding. The solubility of ATH in water, 0.1 mol/L hydrochloric acid solution, and phosphate buffer solution (pH = 7.4) is more than four times that of acipimox, indicating that the solubility of ATH is superior to that of acipimox. Moreover, ATH is more stable than acipimox in solution (298 K), light (4500 LX), high temperature (333 K), and high humidity (92.5%). Favorable solubility and stability of ATH may provide new potential for practical applications.