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Superstructural Ordering in Hexagonal CuInSe2 Nanoparticles
摘要： Chalcogenide semiconducting nanoparticles are promising building blocks for solution-processed fabrication of optoelectronic devices. In this work, we report a new large-scale colloidal synthesis of metastable CuInSe2 nanoparticles with hexagonal plate-like morphology. Powder X-ray diffraction analysis of the nanoparticles showed that the structure of the nanoparticles is not simple hexagonal wurtzite-type CuInSe2 (space group P63mc), indicating the formation of an ordered superstructure. Detailed insight into this structural aspect was explored by high-resolution electron microscopy, and the results evidence an unreported chemical ordering within the synthesized CuInSe2 nanoparticles. Specifically, while the Se sublattice is arranged in perfect wurtzite subcell, Cu and In are segregated over distinct framework positions, forming domains with lower symmetry. The arrangement of these domains within the hexagonal Se substructure proceeds through the formation of a number of planar defects, mainly twins and antiphase boundaries. As a semiconductor, the synthesized material exhibits a direct optical transition at 0.95 eV, which correlate well with its electronic structure assessed by density functional theory calculations. Overall, these findings may inspire the design and synthesis of other nanoparticles featuring unique chemical ordering; thus, providing an additional possibility of tuning intrinsic transport properties.
关键词： hexagonal plate-like morphology,Chalcogenide,CuInSe2,direct optical transition,chemical ordering,semiconducting nanoparticles
更新于2025-09-09 09:28:46
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Effects of polymeric filler on polarization fatigue of 1-3 0.74Pb(Mg <sub/>1/3</sub> Nb <sub/>2/3</sub> )O <sub/>3</sub> -0.26PbTiO <sub/>3</sub> single crystal/polymer composites
摘要： Polarization fatigue tests have been conducted on both bulk Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) single crystals and two 1-3 PMN-xPT/polymer composites with both “soft” and “hard” epoxy fillers, respectively. The variations of remnant polarization, coercive electric field, and micro-crack morphology under 10 Hz cyclic electric loading were studied. It was found that the magnitude of coercive field for both composites was higher compared to that of single crystals. However, as the number of cycles increases, the degradation ratio of remnant polarization and the increased portion of coercive field for both composites were lower than that of single crystals; the sequence is PMN-0.26PT bulk single crystal > 1-3 PMN-0.26PT/soft epoxy composites > 1-3 PMN-0.26PT/hard epoxy composites. In addition, the observed micro-crack propagation morphology shows that 1-3 PMN-0.26PT/hard epoxy composites can substantially improve fatigue-resistance owing to the lower stretching strain benefiting from the polymeric filler. Our results indicated that 1-3 PMN-0.26PT/polymer composites present much better electric polarization stability.
关键词： epoxy fillers,PMN-xPT single crystals,polymer composites,micro-crack morphology,polarization fatigue
更新于2025-09-09 09:28:46
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Responses of Morphology, Gas Exchange, Photochemical Activity of Photosystem II, and Antioxidant Balance in Cyclocarya paliurus to Light Spectra
摘要： Light quality is a critical factor regulating photosynthetic capacity which directly affects the final yield of plants. Cyclocarya paliurus is a multiple function tree species and its leaves are widely used as tea production and ingredient in China. However, the effects of varying light quality on photosynthetic process and the photoprotective mechanisms remains unexplored in-depth. In this study, the biomass accumulation, morphology changes, photosynthetic capacity, stomata ultrastructure, pigments content, PSII activity, reactive oxygen species production, antioxidant enzymes, and phenolic content of C. paliurus plants under different light-emitting diodes (LED) light treatments were investigated to test a hypothesis that the difference in photosynthetic efficiency of C. paliurus plants under differential light quality is related to the degree of photoinhibition and the activation of photoprotection. We found that C. paliurus plants performed better under the treatments of WL (white light, 445 and 560 nm) and BL (blue light, 456 nm) than the treatment of GL (green light, 514 nm) and RL (red light, 653 nm). The better performances were characterized by higher values of photosynthetic capacity, total biomass, pigments content, specific leaf mass per area, seeding height increment, leaf thickness and palisade length. In contrast, plants under the treatments of GL and RL suffered significant photoinhibition but effectively developed photoprotective mechanisms. Results of this study provide not only some insights of the response mechanisms of plant photosynthesis to light quality but also a scientific basis for improving the cultivation of C. paliurus plantations.
关键词： PSII activity,Cyclocarya paliurus,antioxidant balance,morphology,light quality,pigments content
更新于2025-09-09 09:28:46
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Composition, Morphology, Structure and Photocatalytic Performances of Photocatalysts Prepared from Titanium Potassium Oxalate
摘要： In this work, different products were synthesized using potassium titanium oxalate as the precursor when the reaction conditions varied. The influences of reaction system conditions on the formation features, particle size, phase composition, morphology and properties of the products were investigated and discussed. The XRD and SEM results indicated that TiO2 with different morphology and particle size were prepared by a hydrothermal treatment of the reaction system including HCl and H2O2 solution, and its degradation rate reached 100% after 100 min under UV irradiation. However, under the conditions without H2O2, a new product C2O7Ti2·3H2O with a large crystal of hexagonal prism was synthesized. Photocatalytic degradation of methyl orange (MO) indicated that C2O7Ti2·3H2O exhibited high photocatalytic activity. And the results of the active species detection show that ?O2? was the main reactive species for MO degradation. The formation mechanism of the product prepared by different reaction system was also discussed.
关键词： Titanium potassium oxalate,Morphology control,Photocatalytic activity,C2O7Ti2·3H2O,TiO2
更新于2025-09-09 09:28:46
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Theoretical and Experimental Evidence of Modified Structure, Magnetism and Optical Properties in Ba and Mn Co-Substituted BiFeO <sub/>3</sub>
摘要： To improve the vacancy related defects associated with pure BiFeO3 (BFO) different Ba-Mn co-doped samples (Bi1-xBaxFeyMnyO3; x=0.1; y=0.0, 0.05, 0.1, 0.15) were prepared from sol-gel method. The influence of co-doping on structural, magnetic and optical properties of BiFeO3 has been studied in different experimental conditions. Particle size and magnetic properties were measured from SEM and VSM analysis respectively. Again band gap was calculated from UV analysis. The co-doped samples showed reduced particles size as well as better surface morphology. M-H loops suggest that the presence of Mn2+ increased ferromagnetic quantity at some levels. Still room temperature occurrence of ferromagnetism obtained from M-H loops of all samples showed weak ferromagnetic behaviour. In addition the incorporation of Ba2+ at Bi3+ site and Mn2+ at Fe3+ site decreased the band gap which was evidenced by increased optical property.
关键词： Surface morphology,Ferromagnetism,BFO,Multiferroics,Band gap
更新于2025-09-09 09:28:46
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The diagnosis of nasopharyngeal carcinoma by optical coherence tomography (OCT)
摘要： We have attempted to explore the intrinsic differences in the optical properties of the nasopharyngeal carcinoma (NPC) and normal tissue by optical coherence tomography (OCT). OCT imaging of normal tissue provided three layers of epithelium, lamina propria, and the brighter interface of basement membrane; while carcinomas disrupted the layered construction embedded in signal-poor images. The morphologies were consistent with histological findings. Sensitivity and specificity were 90% and 100%, respectively. This pilot study demonstrates that NPC could be diagnosed by visualization, which implies that OCT might be potentially used to differentiate normal from NPC tissue in the early stage as an invasive biopsy.
关键词： morphology,NPC,OCT,early diagnosis
更新于2025-09-09 09:28:46
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Innovative low temperature plasma approach for deposition of alumina films
摘要： Alumina films were deposited from a new plasma method using aluminum acetylacetonate (AAA) powder as precursor. The AAA was sputtered in argon and oxygen plasma mixtures. It was investigated the effect of the oxygen proportion (O2%) on the properties of the coatings. Deposition rate was derived from the layer height measured by profilometry. The elemental composition and molecular structure of the films were determined by Rutherford backscattering and infrared spectroscopies, respectively. Grazing incidence X-ray diffraction was used to investigate the microstructure of the films while hardness was determined by nanoindentation technique. Inspections on the surface morphology and on the film composition were conducted associating scanning electron microscopy and energy dispersive spectroscopy. Incorporation of oxygen affects the plasma kinetics and consequently the properties of the coatings. As moderated concentrations of oxygen (< 25%) are added, the structure is predominantly organic containing stoichiometric amorphous alumina. On the other hand, as high O2% (> 25%) are incorporated, the structure become rich in metallic aluminum with carbon rising at low proportions. The deposited layer is not homogeneous in thickness once the chemical composition of the precursor is changed by the action of the reactive oxygen plasma. Oxygen ablation on the film surface also contributes to the lack of homogeneity of the structure, especially as high oxygen proportions are imposed. Hardness data (0.5-2.0 GPa) corroborated the idea of an amorphous structure. Based on the results presented here it was possible to identify the oxygen concentration in the plasma atmosphere which mostly removed organics while preserving the stoichiometric alumina precipitation, subject of great relevance as one considers the reduction in the energy necessary for the creation of fully oxide coatings.
关键词： composition,reactive plasma sputtering,aluminum acetylacetonate,morphology,alumina,structure
更新于2025-09-04 15:30:14
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Effect of Anodization Parameters on the Surface Morphology and Photoelectrochemical Properties of TiO2 Nanotubes
摘要： Titanium sheets are anodized to prepare titanium dioxide nanotubes (TiO2 NTs) with varying chemical polishing times, anodizing voltages, anodizing times and NH4F electrolyte concentrations. The surface morphology of the TiO2 NTs is observed by a Scanning Electron Microscope (SEM) and used to characterize the inner diameter (di), centre to centre distance (l) and wall thickness (w). The photoelectrochemical performance of TiO2 NT arrays is described by measurements of the photocurrent density and the incident photon to current efficiency (IPCE). The data show l can be controlled by the anodizing voltage; in contrast, di and w are influenced by the anodizing time and NH4F electrolyte concentration. Furthermore, the effects of the anodization parameters on the TiO2 NTs’ surface morphology were determined to influence each other. Using the optimum condition of an anodizing voltage of 60 V at 60 min in 0.125 mass % NH4F ethylene glycol, TiO2 NTs were fabricated that showed a photocurrent density of 90.42 μA /cm2 and maximum IPCE of 18.76 % at 300 nm. The results indicate that the effects of the anodization parameters on the photocurrent response of TiO2 NTs are primarily achieved through control of the wall thickness and the ratio of the diameter to the wall thickness (di / w). For a wall thickness that is greater than a critical value, the ratio di / w can reach a range in which the TiO2 NTs show a high photocurrent output.
关键词： surface morphology,wall thickness,TiO2 nanotubes,anodization,photoelectrochemical property
更新于2025-09-04 15:30:14
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A Novel Multi-View-Angle Range Images Generation Method for Measurement of Complicated Polyhedron in 3D Space
摘要： A new kind of generation method is proposed in this paper to acquire range images for complicated polyhedron in 3D space from a series of view angles. In the proposed generation method, concept of three-view drawing in mechanical cartography is introduced into the range image generation procedure. Negative and positive directions of ??-, ??-, and ??-axes are selected as the view angles to generate the range images for complicated polyhedron in 3D space. Furthermore, a novel iterative operation of mathematical morphology is proposed to ensure that satisfactory range images can be generated for the polyhedron from all the selected view angles. Compared with the existing method based on single view angle and interpolation operation, structure features contained in surface of the complicated polyhedron can be represented more consistently with the reality by using the proposed multi-view-angle range images generation method. The proposed generation method is validated by using an experiment.
关键词： laser scanning,3D space,mathematical morphology,multi-view-angle,complicated polyhedron,range images
更新于2025-09-04 15:30:14
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Effect of surfactants on the performance of 3D morphology W18O49 by solvothermal synthesis
摘要： Three-dimensional W18O49 nanostructures were synthesized by a solvothermal method using WCl6 as precursor and ethanol as solvent. The effects of surfactant on the crystalline phase and morphology of tungsten oxide were investigated. It was found that the photothermal conversion performance and the nanostructures were affected by the surfactant additives. The results of XRD, SEM, TEM, BET and XPS indicated that the addition of surfactant had no effect on the composition of the samples, while the morphology of the sample changed from the irregular massive structure to the uniform polygon, lamellar or nest structures. The results of DRS and heat resistance test showed that the film had excellent infrared shielding properties. The sample synthesized by the adding of cetyltrimethylammonium bromide (CTAB) surfactant showed only 34.04% transmittance in the infrared wavelength range, while the transmittance maintained at high level of 77.5% in the visible range. It reached to higher heat resistance of 6.5 °C under 1 h sunlight irradiation than other samples, the temperature change was only 41.7% of the blank test.
关键词： Nanometer W18O49 powder,Solvothermal synthesis,Morphology,Surfactants
更新于2025-09-04 15:30:14