Crystal Research and Technology最新文献

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.

Tellurite glass and anti-glass samples of two systems: 12.5Bi₂O₃–12.5Nb₂O₅–(75-x)TeO₂–xNd₂O₃ and 7.5Bi₂O₃–7.5Nb₂O₅–(85-x)TeO₂–xNd₂O₃; x = 0 and 1 mol% are prepared by melt–quenching. Transparent glass-ceramics (TGCs) containing anti-glass inclusions co-existing with the glass are prepared by heat–treatment 26 °C above their respective glass transition temperatures. Heating at a higher temperature of 510 °C formed opaque crystalline samples. The effects of Nd³⁺ doping and heat treatment on the samples are studied by X–ray diffraction (XRD), density measurements, Differential scanning calorimetry (DSC), micro-Raman, and UV–visible spectroscopy. The growth of inclusions of anti-glass phases in the TGCs is confirmed by optical microscopy. XRD studies showed sharp peaks of orthorhombic BiNbTe₂O₈ and TeO₂ phases in TGC samples. DSC studies found that the addition of Nd³⁺ enhances the glass transition temperature. Micro-Raman studies found very similar spectra in both anti-glass inclusions and glass matrix confirming that the anti-glass inclusions have vibrational disorder. The size of inclusions is found to be higher in Nd³⁺ doped sample containing lower concentration of Bi₂O₃ and Nb₂O₅ (7.5 mol%). The Nd³⁺ doped samples exhibit broad near-infrared emission bands on excitation with 785 nm laser light.

The bonding features of sesquioxides have been thoroughly investigated by precise experimental charge density distribution using the Maximum Entropy Method (MEM) and multipole models of charge density. The topology of the charge density is investigated and the atoms enacting different bonding characteristics and vibrations at different symmetries are well documented by studying (3,-1) bond critical points. The intermediate nature of interactions are visibly evident in the systems and are mapped. In the course of study, evidences of an increase in closed-shell interaction characteristics of bonding with the increase in the oxidation state of the metal cations in binary oxides are also witnessed. Thermal vibration parameters and charge density at the mid-bond regions, observed in the compound Y₂O₃, shows that its lattice is more rigid and has more covalent character than Al₂O₃ and In₂O₃. The charge integration studies explored the high ionic conductivity nature of In₂O₃.

In this study, an organic nonlinear optical single crystal, creatininium p-toluene sulphonate (CPTS), is synthesized and grown using slow solvent evaporation in an aqueous medium at ambient conditions. Single-crystal X-ray diffraction demonstrates an orthorhombic structure with non-centrosymmetric space group P2₁2₁2₁. Phase purity and specific (hkl) planes are verified by powder X-ray diffraction, while Fourier-transform infrared spectroscopy identifies functional groups within CPTS. Crystalline integrity of the harvested single crystal is assessed through high-resolution X-ray diffraction techniques. High-resolution X-ray diffraction assessed crystal integrity, and microhardness testing categorized CPTS as a soft material. Growth patterns are investigated using surface etching analysis. UV–vis–NIR absorbance and photoluminescence studies provide optical properties. Third-order nonlinearity studies are performed on a thin, well-cut, and polished single crystal using the Z-scan technique, revealing a nonlinear refractive index of $��-�6.87�\times �{10}^{�-�14��}�m^2�/�W�$ and a nonlinear absorption coefficient of $��6.08�\times �{10}^{�-�7�}�m�/�W�$.

In this work, the effects of Ti content on the electrochromic properties of TiWO₃ films are investigated. These films with a nanorod structure are prepared by oblique angle deposition (OAD) in the sputtering process. Sputtered films with a thickness of 100 nm of W and W: Ti for ratios of 5:95 and 50:50 wt.% are thermally oxidized at 500 °C for 1 h. The WO₃ nanorod films exhibit a clear crystalline structure, whereas the TiWO₃ nanorod films show decreased crystallinity, retaining the crystalline structure of WO₃. Moreover, the TiO₂ phase appeared in the presence of W: Ti is 50:50 wt.%. The thermally oxidized films show a clear grain cluster-forming surface. The WO₃ nanorod films exhibit the highest optical contrast of 0.485 with a coloration efficiency of 10.129% and superior electrochromic performance compared to TiWO₃ nanorod films. Meanwhile, the TW5 films reveal a significant increase in the CV loop, demonstrating the most effective test cycle for electrochromic applications.