Search Results (237)

The impact of 230-MeV Xe¹³² ion irradiation on the structural, optical, and luminescent properties of YAG:Ce single crystals is investigated over a fluence range of 10¹¹–10¹⁴ ions/cm². Optical absorption; cathodo-, X-ray, and photoluminescence; and X-ray diffraction are employed to analyze radiation-induced changes. Irradiation leads to the formation of Frenkel (F, F⁺) and antisite defects and attenuates Ce³⁺ emission (via enhanced nonradiative processes and Ce³⁺ → Ce⁴⁺ recharging). A redistribution between the fast and slow components of the Ce³⁺-emission is considered. Excitation spectra show the suppression of exciton-related emission bands, as well as a shift of the excitation onset due to increased lattice disorder. XRD data confirm partial amorphization and a high level of local lattice disordering, both increasing with irradiation fluence. These findings provide insight into radiation-induced processes in YAG:Ce, which are relevant for its application in radiation–hard scintillation detectors. Full article

This work investigates on how Fe incorporation influences the surface, microstructural, and optical properties of solution precursor plasma-sprayed TiO₂ coatings. The Fe-TiO₂ coatings were prepared using titanium isopropoxide and iron acetylacetonate as precursors, with ethanol as the solvent. X-ray diffraction analysis revealed the existence of both anatase and rutile TiO₂ phases, with a predominant rutile phase, also confirmed by Raman spectroscopy. There was an increase in the anatase crystals upon the addition of Fe ions. A longer spray distance further enhanced the anatase content and reduced the average TiO₂ crystallite sizes present in the Fe-added coatings. SEM cross-sectional images displayed finely grained, densely packed deposits in the Fe-added coatings. UV-Vis spectroscopy showed visible-light absorption by the Fe-TiO₂ coatings, with reduced band gap energies ranging from 2.846 ± 0.002 eV to 2.936 ± 0.003 eV. Photoluminescence analysis showed reduced emission intensity at 356 nm (3.48 eV) for the Fe-TiO₂ coatings. These findings confirm solution precursor plasma spray to be an effective method for developing Fe-TiO₂ coatings with potential application as visible-light-active photocatalysts. Full article

With the increasing market demand for spinels of various colors, purple spinel—long regarded as a symbol of nobility—has attracted growing attention. In this study, pinkish-purple to purple spinels from the Mogok region of Myanmar were systematically examined using conventional gemological, spectroscopic, and chemical analytical techniques. Raman analysis reveals that these spinels commonly contain octahedral inclusions composed of calcite, dolomite, magnesite, and graphite. Chemically, the samples are primarily magnesia-alumina spinels. Color variation is influenced by trace elements: increasing Cr and V contents enhance the red hue, while higher Fe concentrations intensify the purple tone. UV–Vis spectra show that Cr³⁺ and V³⁺ jointly contribute to absorptions at 388 nm and 548 nm, with Fe²⁺ and Fe³⁺ responsible for the bands at 371 nm and 457 nm, respectively, together controlling the pink-to-purple color variation. Most samples display four Cr³⁺-related peaks near 700 nm; however, these are absent in deeply purple spinels. In contrast, light pink spinels show weaker absorption at 371 nm and 457 nm, attributed to Fe²⁺ and Fe³⁺. Fluorescence spectra confirm characteristic Cr³⁺ emission bands at 673 nm, 684 nm, 696 nm, 706 nm, and 716 nm, indicating a strong crystal field environment. Raman spectra have peaks mainly around 312 cm⁻¹, 406 cm⁻¹, 665 cm⁻¹, and 768 cm⁻¹. The peaks of the infrared spectrum mainly appear around 840 cm⁻¹, 729 cm⁻¹, 587 cm⁻¹, 545 cm⁻¹, and 473 cm⁻¹. Full article

Mn²⁺-doped phosphors emitting green light have garnered significant interest due to their potential applications in display technologies and solid-state lighting. To facilitate the rapid synthesis of high-performance Mn²⁺-activated green phosphors, this research optimizes a microwave-assisted solid-state (MASS) method for the preparation of Na₂ZnGeO₄:Mn²⁺. Leveraging the unique attributes of the MASS technique, a systematic investigation into the applicability of various Mn-source precursors was conducted. Additionally, the integration of the MASS approach with traditional solid-state reaction (SSR) methods was assessed. The findings indicate that the MASS technique effectively incorporates Mn ions from diverse precursors (including higher oxidation states of manganese) into the crystal lattice, resulting in efficient green emission from Mn²⁺. Notably, the photoluminescence quantum yield (PLQY) of the sample utilizing MnCO₃ as the manganese precursor was recorded at 2.67%, whereas the sample synthesized from MnO₂ exhibited a remarkable PLQY of 17.69%. Moreover, the post-treatment of SSR-derived samples through the MASS process significantly enhanced the PLQY from 0.67% to 8.66%. These results underscore the promise of the MASS method as a novel and efficient synthesis strategy for the rapid and scalable production of Mn²⁺-doped green luminescent materials. Full article

This research examines the effect of annealing temperature on the growth orientation of zinc oxide (ZnO) nanorods and its subsequent influence on NO₂ gas sensing efficiency. Zinc oxide (ZnO) nanorods were synthesized using the chemical bath deposition method, followed by annealing at 300, 400, and 500 °C. Diffraction analysis confirmed that both non-annealed and annealed ZnO nanorods crystallize in a hexagonal wurtzite structure. However, increasing the annealing temperature shifts the growth orientation from the c-axis (002) toward the (100) and (101) directions. Microscopy images (FE-SEM) revealed a reduction in nanorod diameter as the annealing temperature increases. Optical characterization using UV–visible and photoluminescence spectroscopy indicated shifts in the band gap energy and emission properties. Contact angle measurements demonstrated the hydrophobic nature of the films. Gas sensing tests at 200 °C revealed that the ZnO thin film annealed at 400 °C achieved the highest NO₂ response of 5.88%. The study highlights the critical role of annealing in modifying the crystallinity, growth orientation, and defect states of ZnO thin films, ultimately enhancing their NO₂ detection capability. Full article

We report the fabrication and characterization of Al-doped ZnO (AZO) optoelectronic synaptic devices based on sol–gel-derived thin films with varying Al concentrations (0~4.0 wt%). Structural and optical analyses reveal that moderate Al doping modulates the crystal orientation, optical bandgap, and defect levels of ZnO films. Notably, 2.0 wt% Al doping yields the widest bandgap (3.31 eV), stable PL emission, and uniform deep-level absorption without inducing significant lattice disorder. Synaptic performance, including learning–forgetting dynamics and persistent photoconductivity (PPC), is strongly dependent on Al concentration. The 2.0 wt% AZO device exhibits the lowest forgetting rate and longest memory retention due to optimized trap formation, particularly Al–oxygen vacancy complexes that enhance carrier lifetime. Visual memory simulations using a 3 × 3 pixel array under patterned UV illumination further confirm superior long-term memory (LTM) behavior at 2.0 wt%, with stronger excitatory postsynaptic current (EPSC) retention during repeated stimulation. These results demonstrate that precise doping control via the sol–gel method enables defect engineering in oxide-based neuromorphic devices. Our findings provide an effective strategy for designing low-cost, scalable optoelectronic synapses with tunable memory characteristics suitable for future in-sensor computing and neuromorphic vision systems. Full article

Phosphogypsum, a byproduct of phosphate fertilizer production, represents a significant environmental concern due to its large-scale production and low utilization rates. Although preparing phosphogypsum-based cementitious materials offers a potential solution to these issues, high-content phosphogypsum cementitious systems encounter significant technical barriers, including long setting durations and insufficient early-age strength development, thereby restricting their practical implementation. Hence, this research developed innovative modifiers through an environmentally friendly low-temperature thermal activation process (100–160 °C) utilizing recycled phosphogypsum aggregates and circumventing the substantial carbon emissions associated with conventional modification approaches. Systematic characterization demonstrated that the dehydration phase modifier synthesized at 120 °C (DH120) exhibited optimal phase composition, resulting in a 35.7% enhancement in its 14-d compressive strength (9.8 MPa vs. 7.2 MPa for the control) and an 11.3% reduction in its initial setting time (27.5 vs. 31.0 h for the control). Microstructural characterization by low-field nuclear magnetic resonance and X-ray diffractometry revealed that DH120 effectively enhanced refinement of the pore structure (37.7% mesopore volume reduction) and promoted the ettringite crystallization kinetics. This work establishes a sustainable framework for utilizing industrial byproducts in cementitious material systems. Full article

Intercrystal scatter reduces system sensitivity and spatial resolution, a phenomenon that has been extensively studied in positron emission tomography (PET) systems. However, the issue is even more significant in high-energy systems. The purpose of this study is to propose a practical crosstalk rejection technique and demonstrate its applicability in high-energy photon-counting systems. The effect of inter-crystal scattering interactions between ⁶⁰Co γ photons and lutetium yttrium oxyorthosilicate (LYSO) scintillator crystals is investigated through Monte Carlo simulations conducted using the Geant4 toolkit. To suppress the crosstalk phenomenon, a field-programmable gate array (FPGA)-based algorithm is proposed to suppress inter-crystal scattering events, characterized by a time window of 5 nanoseconds and detector window sizes of one or two. The 250 mm Fe steel penetration model is used to evaluate the proposed algorithm, showing improved radiation image quality, particularly with a detector window size of two, which performs better under low-count-rate conditions. Laboratory testing indicates that the proposed algorithm can enhance steel penetration (SP) by 60–70 mm of Fe when compared to the existing current integration system under the same settings. The suggested method has been proven effective in producing higher-quality images and demonstrates good adaptability by adapting the detector window width according to different system count rates. Full article

This study evaluates the manufacturing accuracy of Merlon fracture models produced using two vat-photopolymerization-based three-dimensional (3D) printers: digital light processing (DLP) and liquid-crystal display (LCD). The Merlon fracture model is used to assess dimensional precision and machining accuracy. The root mean square (RMS) values, wall and bottom thicknesses, and field-emission scanning electron microscopy images are analyzed. The DLP-based printers exhibit lower RMS values and superior accuracy compared with LCD-based printing and subtractive milling. Polymer-based slurries for permanent dental applications exhibit better dimensional stability than those for temporary restorations. This study also highlights the significant impact of postprocessing and cleaning procedures on the final model accuracy. These findings suggest that optimizing the postprocessing parameters is crucial for enhancing the precision of 3D-printed dental restorations. The Merlon fracture model is a viable method for evaluating additive manufacturing accuracy, contributing to the improved clinical application of vat photopolymerization in dental prosthetics. Full article

Mn²⁺ doping in metal halide perovskites enables host-to-dopant energy transfer, creating new emission pathways for optoelectronic applications. However, achieving high-efficiency luminescence in 2D systems remains challenging. We synthesized Mn²⁺-doped 2D PEA₂CdCl₄ via the hydrothermal method, characterizing its properties through PL spectroscopy, quantum yield measurements, and DFT calculations. Flexible films were fabricated using PDMS and PMMA matrices. The 15% Mn²⁺-doped crystal showed orange–red emission with 90.85% PLQY, attributed to efficient host-to-Mn²⁺ energy transfer and ⁴T₁→⁶A₁ transition. Prototype LEDs exhibited stable emission, while PDMS films demonstrated flexibility and PMMA films showed excellent X-ray imaging capability. This work demonstrates Mn²⁺ doping as an effective strategy to enhance luminescence in 2D perovskites, with potential applications in flexible optoelectronics and X-ray scintillators. Full article

Melt crystallization is a promising separation technique that produces ultra-high-purity products while consuming less energy and generating lower CO₂ emissions than conventional methods. However, accurately modeling melt crystallization is challenging due to significant non-idealities and complex phase equilibria in multicomponent systems. This study develops and evaluates two neural network-based surrogate models for acrylic acid melt crystallization: a stand-alone (black-box) model and a thermodynamically guided (hybrid) model. The hybrid model incorporates UNIQUAC-based solid–liquid equilibrium constraints into the learning process. This framework combines first-principles thermodynamic knowledge—particularly activity coefficient calculations and mass balance equations—with multi-output regression to predict key process variables. Both models are rigorously tested for interpolation and extrapolation, with the hybrid approach demonstrating superior accuracy even under operating conditions significantly outside the training domain. Further analysis reveals the critical importance of accurate solid–liquid equilibrium (SLE) data for thermodynamic parameterization. A final case study illustrates how the hybrid approach can quickly explore feasible operating regions while adhering to strict product purity targets. These findings confirm that integrating mechanistic constraints into neural networks significantly enhances predictive accuracy, especially when processes deviate from nominal conditions, providing a practical framework for designing and optimizing industrial-scale melt crystallization processes. Full article

To address the environmental pressures and resource waste caused by massive stockpiling of steel slag, this study developed a carbonated steel slag pervious concrete binder using 40% steel slag powder as the primary cementitious component combined with CaO and MgO. The mechanical performance evolution was investigated, while XRD, SEM, and TG-DTG microcharacterization techniques were employed to reveal the carbonation mechanism and strength formation principles. The results demonstrate that when CaO and MgO contents reached 5% and 15%, respectively, the 28d compressive strength of mortar increased by 134.49% compared to the reference group. Microstructural analysis confirmed that CaO reacted to form CaCO₃ crystals, while MgO enhanced strength by regulating CaCO₃ crystal morphology to optimize product structure. Using steel slag as an aggregate, carbonated steel slag pervious concrete was prepared to investigate the influence mechanisms of B/A ratio and W/B ratio on compressive strength, permeability coefficient, and carbonation effects. The post-carbonation strength increase was adopted to evaluate carbonation efficiency. Increasing B/A ratio enhanced paste filling in aggregate voids, raising 28d compressive strength to 24.76 MPa, but thickened paste coating layers reduced permeability coefficient to 0.33 mm/s while impeding CO₂ diffusion, decreasing carbonation strength growth rate by 22.76%. Initial W/B ratio elevation improved workability to increase strength to 23.76 MPa, whereas excessive water caused paste sedimentation and strength reduction. As W/B ratio rose, permeability coefficient decreased by 65.6%, while carbonation strength growth rate increased. The carbonated steel slag pervious concrete contained approximately 82% steel slag, demonstrating high resource utilization efficiency of steel slag and significant potential for carbon emission reduction. Full article

The development of advanced biomaterials for dental applications has gained significant attention due to the need for enhanced mechanical properties, biocompatibility, and antibacterial activity. Hydroxyapatite (HA) is widely used in bone tissue engineering owing to its chemical similarities to bone. However, biofilm formation and bacterial infection on HA may lead to implant failure and revision surgery. Tannic acid, a polyphenolic compound with strong antibacterial and antioxidant properties, was incorporated into the composite to provide antimicrobial effects, that may address the challenge of biofilm formation on dental surfaces. In this study, the biomedical potential of tannic acid (TA)-loaded hydroxyapatite-zirconia composites were analyzed. The crystallization characteristics, functional groups, and morphology were analyzed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FESEM) analysis. The biocompatibility of composite samples was analyzed through in vitro cell culture studies. The combined effect of TA and zirconia showed antibacterial efficacy against Staphylococcus aureus (S. aureus) after 24 h of sample–bacterial interactions. The results demonstrate that this tannic acid-loaded hydroxyapatite-zirconia composite holds significant promise for improving the performance of dental materials and preventing infections in oral healthcare applications. Full article

Changes in microRNA (miRNA) levels are closely associated with the pathological processes of many diseases. The sensitive and fast detection of miRNAs is critical for diagnosis and prognosis. Here, we report a platform employing CRISPR/Cas12a to recognize and report changes in miRNA levels while avoiding complex multi-thermal cycling procedures. A non-enzyme-dependent hybridization chain reaction (HCR) was used to convert the miRNA signal into double-stranded DNA, which contained a Cas12a activation sequence. The target sequence was amplified simply and isothermally, enabling the test to be executed at a constant temperature of 37 °C. The detection platform had the capacity to measure concentrations down to the picomolar level, and the target miRNA could be distinguished at the nanomolar level. By using photonic crystal microarrays with a stopband-matched emission spectrum of the fluorescent-quencher modified reporter, the fluorescence signal was moderately enhanced to increase the sensitivity. With this enhancement, analyzable fluorescence results were obtained in 15 min. The HCR and Cas12a cleavage processes could be conducted in a single tube by separating the two procedures into the bottom and the cap. We verified the sensitivity and specificity of this one-pot system, and both were comparable to those of the two-step method. Overall, our study produced a fast and sensitive miRNA detection platform based on a CRISPR/Cas12a system and enzyme-free HCR amplification. This platform may serve as a potential solution for miRNA detection in clinical practice. Full article

Recently, Cu(I)-based metal halides have attracted tremendous attention owing to their remarkable photophysical properties. However, most of them can only be excited by near ultraviolet (UV) light at a wavelength (generally less than 350 nm) with a wide bandgap, which undoubtedly limits their application in solid-state lighting due to the low excitation efficiency at about 400 nm in devices. Here, we report a new zero-dimensional organic cuprous bromide of (C₁₃H₃₀N)₂Cu₅Br₇ single crystals, which can be excited by visible light (390–400 nm) and give a bright yellow and broad self-trapped exciton emission band with the photoluminescence quantum yield (PLQY) of 92.3% at room temperature. The experimental and theoretical results show that the existence of Cu-Br-Cu metal bonds in a Cu₅Br₇ cluster package produces three components of self-trapped excitons (STE) that emit at room temperature but merge into one at 80 K. This occurs because of the anomalously enhanced electron–phonon coupling and electron–electron coupling in the coupled clusters in this system. These effects cause the excitation near visible light and emission broader at higher temperature. Additionally, their remarkable anti-water emission stability was demonstrated even after soaking in water for 6 h. Finally, a highly efficient white-light-emitting diode (WLED) based on (C₁₃H₃₀N)₂Cu₅Br₇ was fabricated. Full article