Crystal Research and Technology最新文献

In this work, the electronic structures and optical features of the SrZnSi and SrZnGe half-Heuslers are elucidated using the GGA-PBE approach and the TB-mBJ potential. The formation energies are negative, suggesting that these Heuslers appear to be thermodynamically stable. Both materials are more stable in the type II cubic structure, and their structural constants are consistent with the experimental data, and they satisfy the stability criteria with brittle behavior. In ultraviolet (UV), maximum reflectivity and absorption are found for both materials with directgaps of 1.0 and 0.535 eV, respectively, for SrZnSi and SrZnGe. Therefore, the SrZnSi and SrZnGe are potentially suitable materials for photovoltaic applications.

Aiming at the problems of low crystallization rate and uneven particle size during evaporative crystallization of ammonium sulfate mother liquor (a by-product of ammonia desulfurization of sintered flue gas), this study investigated via orthogonal tests the effects of evaporation temperature, pH, stirring rate, and calcium sulfate addition on crystallization amount, average particle size, and coefficient of variation (C.V.). The results showed: For crystallization amount, the influence degree was evaporation temperature>pH>stirring rate>calcium sulfate addition; for average particle size, it was stirring rate>pH>evaporation temperature>calcium sulfate addition; for C.V. value, it was stirring rate>pH>calcium sulfate addition>evaporation temperature. Crystal morphologies included hexahedral, columnar, lamellar, etc., with aggregation under some conditions. Crystals contained calcium, nitrogen, oxygen, and sulfur elements(Ca, N, O, S); Ca content increased with calcium sulfate addition. Ammonium sulfate crystals' diffraction peaks matched pure ammonium sulfate, with the highest peaks at pH 5.0, 250 rpm stirring, 3500 mg·L⁻¹ calcium sulfate, and 333.15K.

This study reports a composite hydrogel composed of ginseng peptides (GGP), cellulose nanocrystals (CNC), and menthol@β-cyclodextrin (β-CD@Menthol). Characterization confirms the successful inclusion of menthol, enhances crystallinity, and a uniform porous structure. The β-CD@Menthol/GGP@CNC hydrogel exhibits high mechanical strength (elongation 1495.4%, toughness 3320.0 kJ m⁻³), strong antioxidant activity (ABTS scavenging 90.9%), excellent swelling capacity (1198.3% in saline), and effective antibacterial effects against Escherichia coli and Staphylococcus aureus. These properties highlight its promise as a multifunctional wound dressing to combat infection and oxidative stress in chronic wounds.

This study employs numerical simulation to analyze the coupled effects of rotation speed difference (Δω) and growth rate (V_g) on thermal stress and oxygen-related defect behavior during Czochralski silicon single crystal growth. The results indicate that increasing Δω enhances shear convection, raises the stress level at the solid–liquid interface, and promotes vacancy formation; when Δω exceeds 12 rpm, vacancy concentration increases linearly, significantly enhancing the formation of VO and VO₂ complexes. Under the same Δω increase, accelerating the crystal rotation leads to a greater rise in VO_x concentration compared to accelerating the crucible. As V_g increases, the S–L interface shifts upward, temperature gradients and thermal stress intensify simultaneously, and the concentrations of VO and VO₂ increase by 26.1% and 25.88%, respectively. Therefore, Δω and V_g exhibit a strong synergistic regulatory effect on the thermal field and point defect evolution. Improper control may lead to excessive generation and accumulation of VO_x defects, ultimately degrading crystal quality. Hence, in practical CZ crystal growth, it is essential to optimize the coordination of Δω and V_g to achieve both high growth efficiency and effective defect suppression.

Cd²⁺-doped potassium dihydrogen phosphate single crystals are prepared by “point seed” method. A significant disparity is identified in Cd concentrations between pyramidal and prismatic samples, with prismatic samples exhibiting higher levels. The ultraviolet–visible (UV–vis) spectra indicate that KDP crystals doped with trace Cd²⁺ exhibit increased transmittance, while those with excessive Cd²⁺ show reduced transmittance in the UV region. Additionally, excessive Cd²⁺ causes light absorption in the band ≈220 nm. Structural analysis is conducted utilizing infrared spectroscopy (IR). The results indicate that Cd²⁺ doping distorts the chemical bonding in KDP crystals and reduces their structural stability. A detailed analysis of the photoluminescence (PL) spectro copy results shows that Cd²⁺ in KDP crystals is related to increased defect concentration. The laser-induced damage threshold (LIDT) results demonstrate that the LIDT of crystals decreases with increasing Cd²⁺ doping concentration. The Cd0-Py sample demonstrates the highest LIDT value of 16.75 J cm⁻² under the R-on-1 condition. The value of Cd1000-Py sample decreases to 7.46 J cm⁻² in the same mode, primarily attributable to the comparatively elevated concentration of micro defects. Differential incorporation of Cd²⁺ into pyramidal versus prismatic sectors is proposed, as substitutional and interstitial defects, accounts for the decrease of laser-induced damage performance of KDP crystal based on the findings and prior reports.

With the continuous development of optical science and technology, there are higher requirements for the versatility and multi-application scenarios of optical devices. Organic–inorganic hybrid birefringent crystals have attracted much attention due to their high flexibility in molecular design and assembly. In this work, an alkaline earth metal 2-hydroxybutanedioate Ba₃(C₄H₄O₅)₂(OH)₂ crystallizing in the C2/c space group is synthesized by the hydrothermal method. Its unit cell parameters are a = 20.0584(7) Å, b = 7.4499(3) Å, c = 9.5087(3) Å, and β = 96.808(2) °. Ba₃(C₄H₄O₅)₂(OH)₂ polycrystalline powder is characterized in detail by Fourier transform infrared (FTIR) absorption spectroscopy, UV–vis–NIR diffuse reflectance spectroscopy, and simultaneous thermal analysis. In addition, theoretical analyses are carried out using first-principles calculations and Hirshfeld surface analysis. The theoretical birefringence of Ba₃(C₄H₄O₅)₂(OH)₂ is calculated to be 0.1 @546 nm. At the same time, UV–vis–NIR diffuse reflectance and band structure calculations show that Ba₃(C₄H₄O₅)₂(OH)₂ has an indirect bandgap of 5.11 eV with a UV cutoff edge of 203 nm. By leveraging the complementary attributes of organic and inorganic materials, Ba₃(C₄H₄O₅)₂(OH)₂ stands out as a promising UV birefringent candidate.

This study investigates the growth and luminescence properties of Na₂Mo₂O₇ crystal for the application in the low-temperature radiation detectors, specifically for neutrinoless double β decay research. φ25 and φ40 mm Na₂Mo₂O₇ transparent crystals are grown by the vertical Bridgman method. The crystal phase is characterized using X-ray diffraction (XRD), Raman spectrometer, thermogravimetric-differential thermal analysis (TG-DTA), and energy dispersive spectroscopy (EDS). UV–vis spectrophotometry reveals that the crystal exhibits high transmittance, reaching up to 84%. Fluorescence spectrometry indicated that the emission spectrum of Na₂Mo₂O₇ reaches its maximum intensity at 80 K. The luminescence decay time increases with decreasing temperature, and the decay time at 10 K is 697.5 µs. The activation energy (E_a) of the crystal is fitted to be 193.3 meV. The result shows that the Na₂Mo₂O₇ crystal has excellent luminescence properties at low temperatures.

A novel one-step chemical vapor deposition approach is introduced for synthesizing high-density vertical molybdenum disulfide (MoS₂) nanoflakes and molybdenum dioxide (MoO₂) structures using pelletized MoO₃/S precursors and abrupt thermal cycling. Unlike conventional multi zone sulfurization methods, the process compacts alternating MoO₃/S/MoO₃/S/MoO₃ layers into 10-ton pressure pellets, ensuring uniform precursor distribution and phase selectivity. Rapid thermal cycling, with an abrupt transition from 25 to 750 °C, followed by rapid cooling after a 5-min deposition under an Ar/H₂ flow, critically influences the crystallization dynamics. A sulfur-to-MoO₃ molar ratio of 2:1 promotes vertical MoS₂ growth (≈100 flakesµm⁻²), whereas a 1.16:1 ratio induces MoO₂ formation with elongated hexagonal morphologies, sizes between (0.70–1.36 µm). This scalable synthesis method offers a reproducible and efficient alternative for nanomaterial fabrication, allowing the production of vertical MoS₂ flakes and enlarged MoO₂ for transfer onto various substrates, as well as uniform vertical structures directly deposited on the substrate. The findings offer key insights into precursor structuring and thermal modulation for the tailored synthesis of 2D materials with applications in catalysis, energy storage, and nanoelectronics.

Magnesium alloy AZ31 surfaces are successfully coated with manganese-doped magnesium phosphate by means of electrochemically assisted deposition. The resulting coatings consist of the magnesium phosphates struvite and newberyite. Topography and composition of the coatings are analyzed by scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. In L929 cell culture experiments, the maximum manganese concentration, which still allowed acceptable cell proliferation, is determined. An optimization of the coating quality regarding thickness and homogeneity is performed using the design of experiment software MODDE. The change in corrosion resistance is determined by measuring the release rate of hydrogen gas in simulated body fluid. The samples with manganese-doped coatings release less gas than the samples with undoped coatings, which in turn release less gas than the uncoated samples. In addition, the magnesium phosphate coating significantly reduces the relative mass loss rate of the magnesium substrates, suggesting it as a promising approach to mitigate the adverse effects of magnesium implant degradation in vivo.