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Understanding the Surfaces and Crystal Growth of Pyrite FeS2
摘要： Pyrite is a common sulfide mineral, which has arisen early interest by its euhedral shape and by its metallic glow similar to gold. However, it is only in our century that we began to understand pyrite crystal growth, considering the thermodynamic and kinetic aspects of crystal formation as a function of temperature and concentration of the elements present in the medium. This article reports an analysis by molecular mechanics of 11 surfaces associated to observed morphologies in order to explain the growth of natural and synthesized minerals. The lowest surface and attachment energies (respectively 1.04 J/m2 and -20.3 kJ/mol) were obtained for the (001) plane, indicating that it is the most stable surface and that kinetic growth also preferentially occurs on this plane. Less known properties, such as crystal striations along the <100> directions, are also discussed.
关键词： pyritohedron,force field,striation,surface,morphology
更新于2025-09-23 15:21:01
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Influence of precursor concentration and growth time on the surface morphology and crystallinity of α-Ga<sub>2</sub>O<sub>3</sub> thin films fabricated by mist chemical vapor deposition
摘要： Single-crystal thin films of gallium oxide (Ga2O3), an ultra-wide bandgap semiconductor, were fabricated on c-plane sapphire by mist chemical vapor deposition (mist CVD). The grown ?-Ga2O3 thin films had low surface roughness, and we characterized their initial crystal growth phase by using atomic force microscopy and X-ray diffraction. By varying the precursor concentration, we changed the surface roughness and crystallinity of the thin films. The lattice constants of the ?-Ga2O3 thin films almost matched those of the single crystal in the initial growth phase. We also found that these thin films grew hetero-epitaxially. Finally, mist CVD might have a very short incubation time in this system.
关键词： Gallium oxide,Surface morphology,Crystallinity,Precursor concentration,Mist chemical vapor deposition,Epitaxial growth,Wide bandgap semiconductors
更新于2025-09-23 15:21:01
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pH Mediated Control Synthesis of Lanthanide-Doped YPO4 Upconversion Nano/Microcrystals
摘要： A pH-mediated rational control over the phase transformation, morphology and size of lanthanide doped YPO4 nano/microcrystals has been accomplished using a hydrothermal route. The morphology of the resulting particles evolves from the spheres, to the nanoflakes and finally to the nanorods when increasing the pH value of the reaction solution from 1 to 9, while the induction of crystal phase transformation from a tetragonal structure to a hexagonal structure takes place at pH = 5. When excited at 980 nm, the hexagonal phase YPO4?0.8H2O: 18%Yb3+, 2%Er3+ nanoflakes prepared at pH = 7 exhibit the strongest UC emission intensity among investigated samples of varying size, phase and morphologies. This work provides a paradigm on the controlled synthesis of lanthanide doped upconverting orthophosphates, which hold great promise for various photonic and biophotonic applications.
关键词： Orthophosphate,Morphology,Upconversion
更新于2025-09-23 15:21:01
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Multi-objective Parameter Auto-tuning for Tissue Image Segmentation Workflows
摘要： We propose a software platform that integrates methods and tools for multi-objective parameter auto-tuning in tissue image segmentation workflows. The goal of our work is to provide an approach for improving the accuracy of nucleus/cell segmentation pipelines by tuning their input parameters. The shape, size, and texture features of nuclei in tissue are important biomarkers for disease prognosis, and accurate computation of these features depends on accurate delineation of boundaries of nuclei. Input parameters in many nucleus segmentation workflows affect segmentation accuracy and have to be tuned for optimal performance. This is a time-consuming and computationally expensive process; automating this step facilitates more robust image segmentation workflows and enables more efficient application of image analysis in large image datasets. Our software platform adjusts the parameters of a nuclear segmentation algorithm to maximize the quality of image segmentation results while minimizing the execution time. It implements several optimization methods to search the parameter space efficiently. In addition, the methodology is developed to execute on high-performance computing systems to reduce the execution time of the parameter tuning phase. These capabilities are packaged in a Docker container for easy deployment and can be used through a friendly interface extension in 3D Slicer. Our results using three real-world image segmentation workflows demonstrate that the proposed solution is able to (1) search a small fraction (about 100 points) of the parameter space, which contains billions to trillions of points, and improve the quality of segmentation output by × 1.20, × 1.29, and × 1.29, on average; (2) decrease the execution time of a segmentation workflow by up to 11.79× while improving output quality; and (3) effectively use parallel systems to accelerate parameter tuning and segmentation phases.
关键词： Parameter auto-tuning,Cancer,Cell morphology,Computer-assisted image analysis,Digital pathology
更新于2025-09-23 15:21:01
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Influence of Film Morphology on Transient Photocurrent Pulse Shape in Organic Thin Films: A Monte Carlo Study
摘要： The in?uence of ?lm morphology on the broadening of the time-of-?ight transient photo-current pulse is investigated using Monte Carlo simulation. Simulation of the time-of-?ight transient photo-current pulse shape is carried out for homogeneous and inhomogeneous organic thin ?lms by varying the overall energetic disorder. In homogeneous system, the value of the tail broadening parameter (W) of the photocurrent pulse is found to decrease upon decreasing the energetic disorder, which can be attributed to the variation in the non-thermal ?eld assisted diffusion. Interestingly, in the case of inhomogeneous system, upon decreasing the overall energetic disorder of the system the value of W initially attains a maximum value before it starts decreasing. This observation is explained in terms of the morphology dependent carrier diffusion. This study asserts the importance of the in?uence of the morphology dependent carrier diffusion on the charge transport in disordered systems and the related experimental measurements.
关键词： Polycrystalline organic thin ?lms,Charge transport,Tail broadening,Diffusion,Time of ?ight photoconductivity,Film Morphology
更新于2025-09-23 15:21:01
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Semiconductor Photocatalysis - Materials, Mechanisms and Applications || Photocatalytic Removal of Organics over BiVO4-Based Photocatalysts
摘要： Organic compounds, such as organic dyes and phenols, are the main pollutants in wastewater. In the past years, a large number of studies on the fabrication and photocatalytic organics degradation of BiVO4 and its related materials have been reported in the literature. In this chapter, we shall focus on the advancements in the synthesis and photocatalytic applications of several kinds of BiVO4-based photocatalysts: (i) well-defined morphological BiVO4 photocatalysts, (ii) porous BiVO4 photocatalysts, (iii) heteroatom-doped BiVO4 photocatalysts, (iv) BiVO4-based heterojunction photocatalysts, and (v) supported BiVO4 photocatalysts. We shall discuss the structure–photocatalytic performance relationship of the materials and the involved photocatalytic degradation mechanisms. In addition, we also propose the research trends and technologies for practical applications of the BiVO4-based photocatalytic materials.
关键词： BiVO4-based heterojunction,well-defined morphology,heteroatom-doped BiVO4,supported BiVO4,porous BiVO4 photocatalyst
更新于2025-09-23 15:21:01
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Automatic Flare Spot Artifact Detection and Removal in Photographs
摘要： Flare spot is one type of ?are artifact caused by a number of conditions, frequently provoked by one or more high-luminance sources within or close to the camera ?eld of view. When light rays coming from a high-luminance source reach the front element of a camera, it can produce intra-re?ections within camera elements that emerge at the ?lm plane forming non-image information or ?are on the captured image. Even though preventive mechanisms are used, artifacts can appear. In this paper, we propose a robust computational method to automatically detect and remove ?are spot artifacts. Our contribution is threefold: ?rstly, we propose a characterization which is based on intrinsic properties that a ?are spot is likely to satisfy; secondly, we de?ne a new con?dence measure able to select ?are spots among the candidates; and, ?nally, a method to accurately determine the ?are region is given. Then, the detected artifacts are removed by using exemplar-based inpainting. We show that our algorithm achieves top-tier quantitative and qualitative performance.
关键词： Mathematical morphology,Inpainting,Flare artifacts,Flare spot,Con?dence measure
更新于2025-09-23 15:21:01
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Additivea??Assisted Hota??Casting Free Fabrication of Diona??Jacobson 2D Perovskite Solar Cell with Efficiency Beyond 16%
摘要： Two-dimensional (2D) Dion-Jacobson (DJ) perovskite solar cells (PVSCs) with high power conversion efficiency (PCE) are currently predominately fabricated via a hot-casting process. The reason lies in the difficulty in preparing high-quality perovskite film under mild condition when the application of divalent ammonium removes the weak interaction from the spacer cation layer. In this work, the morphology of the 2D DJ perovskite film with rigid piperidinium ring is tuned through room-temperature spin-coating method, with the aid of methylammonium thiocyanate (MASCN) additive. With optimized amount of MASCN addition, the perovskite films deposited on poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA)/poly[(9,9-bis(30-(N,N-dimethylamino)propyl)-2,7-uorene)-alt-2,7-(9,9-dioctylfuorene)] (PFN) substrate exhibit fine crystallinity, preferred orientation, decreased defects and better energy level alignment with the hole transport layer. The device with inverted planar structure presents JSC of 17.91 mA cm-2, VOC of 1.19 V, FF of 0.76, with a maximum PCE of 16.25%, which is the highest PCE for 2D DJ PVSCs free of hot-casting. The unsealed device maintained around 80% of its initial efficiency after 35 days exposure to air (Hr = 45 ± 5%). This work provides a potential route towards high performance 2D DJ PVSCs.
关键词： additive,2D perovskite,film morphology,charge transport,growth orientation
更新于2025-09-23 15:19:57
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As-fabricated surface morphologies of Ti-6Al-4V samples fabricated by different laser processing parameters in selective laser melting
摘要： The surface morphology of a product plays a crucial role under mechanical loading and chemical environment. Surfaces of Selective Laser Melting (SLM) products often contain high roughness, which varies in different planes as well. The authors have explored the surface characteristics of the SLM samples that are influenced by different combinations of laser processing parameters. The considered processing parameters were Energy Density (ED) and its technological parameters namely laser power, scanning speed and hatch spacing. Additionally, a comparison study has been executed by rescanning effects considering melting with low ED and, thereafter, re-scanning by the best possible laser processing parameters. The results evidently showed that the surface morphologies differ significantly due to different laser processing parameters. Eventually, the thermal and physical behavior of materials, such as the viscosity of the melt pool, thermal and physical stability of the melt pool, solidification time, cooling time, shrinkage, capillary effect, surface tension, balling effect, and the amount of melting of a powder particle, influenced the surface properties of the samples, along with unpredictability. The results showed an interesting correlation between the processing parameters and the occurrence of microcracks on the vertical walls of the specimens caused by the partially melted adhered powder particles.
关键词： Ti-6Al-4V alloy,Selective laser melting,Laser processing parameters,Surface morphology,Rescanning
更新于2025-09-23 15:19:57
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Simultaneous improvement of three parameters using binary processing solvent approach in as-cast non-fullerene solar cells
摘要： As-cast polymer solar cells without any additive and pre- or post-treatment principally are of high compatibility with mass production technologies, whose efficiencies are typically promoted by new donor and acceptor materials. In this work, a binary solvent approach using chloroform (CF) of low boiling point as good solvent for both polymer donor PTQ10 and non-fullerene acceptor IT-4Cl and mesitylene (MES) of relatively high boiling point as a semi-orthogonal co-solvent due to weaker solubility to the acceptor is explored. Due to the selective orthogonality of MES to the IT-4Cl acceptor, an optimized morphology has been realized for the as-cast device based on the PTQ10:IT-4Cl blend, which leads to a simultaneous improvement in the open-circuit voltage, short-circuit current, and fill factor, finally achieving a high as-cast efficiency of over 13%. Furthermore, the as-cast devices fabricated with the binary solvent can exhibit good air stability and great accessibility in large area cells. Our findings provide an alternative guideline for the optimization of the as-cast polymer solar cells.
关键词： polymer solar cells,morphology optimization,non-fullerene acceptor,binary solvent,as-cast
更新于2025-09-23 15:19:57