The Experts below are selected from a list of 41061 Experts worldwide ranked by ideXlab platform
Byungmin Ahn - One of the best experts on this subject based on the ideXlab platform.
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Understanding High Anisotropic Magnetism by Ultrathin Shell Layer Formation for Magnetically Hard–Soft Core–Shell Nanostructures
Chemistry of Materials, 2019Co-Authors: Kwan H. Lee, Sangyeob Lee, Byungmin AhnAbstract:Magnetic core–Shell nanostructures offer a viable solution for tunable magnetism via nanoscale exchange interactions in a single-component unit. A typical synthetic approach for monodisperse bimagnetic ferrite core–Shell nanostructures employs the seed-mediated growth method using the heating-up process. Understanding magnetic core–Shell interface formation and their interactions is crucial; however, the magnetical persistence of the pristine core component during the heating-up process is unclear. Here, we elucidate the enhancement mechanism of magnetic anisotropy when the hard–soft core–Shell nanostructures are formed with the ultrathin Shell Layer. The heating-up effect on the core component exhibits the coordination change of ligand chemisorption with surface metal ions, which leads to a substantial increase in surface anisotropy due to enhanced spin–orbit couplings. We further demonstrate that the selection of metal precursors and surfactants for additional Shell Layer formation is important. The kin...
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Understanding High Anisotropic Magnetism by Ultrathin Shell Layer Formation for Magnetically Hard–Soft Core–Shell Nanostructures
2019Co-Authors: Kwan Lee, Sangyeob Lee, Byungmin AhnAbstract:Magnetic core–Shell nanostructures offer a viable solution for tunable magnetism via nanoscale exchange interactions in a single-component unit. A typical synthetic approach for monodisperse bimagnetic ferrite core–Shell nanostructures employs the seed-mediated growth method using the heating-up process. Understanding magnetic core–Shell interface formation and their interactions is crucial; however, the magnetical persistence of the pristine core component during the heating-up process is unclear. Here, we elucidate the enhancement mechanism of magnetic anisotropy when the hard–soft core–Shell nanostructures are formed with the ultrathin Shell Layer. The heating-up effect on the core component exhibits the coordination change of ligand chemisorption with surface metal ions, which leads to a substantial increase in surface anisotropy due to enhanced spin–orbit couplings. We further demonstrate that the selection of metal precursors and surfactants for additional Shell Layer formation is important. The kinetic of the Shell formation rate by their thermolysis and atomic-scale surface etching by the surfactant led to the disordering of surface spins on the core parts. Our observations provide the underlying mechanism of high anisotropic magnetism while bimagnetic ferrite core–Shell interface formation and the voyage of synthetic procedures for the additional Shell Layer are critical to an outcoming magnetism
Linqi Shi - One of the best experts on this subject based on the ideXlab platform.
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synthesis of noble metal nanoparticles embedded in the Shell Layer of core Shell poly styrene co 4 vinylpyridine micospheres and their application in catalysis
Chemistry of Materials, 2008Co-Authors: Fei Wen, Wangqing Zhang, Guanwei Wei, Yao Wang, Jianzheng Zhang, Minchao Zhang, Linqi ShiAbstract:The noble metal nanoparticles of Pd, Au, and Ag embedded in the Shell Layer of core−Shell poly(styrene-co-4-vinylpyridine) micospheres were synthesized, and the catalytic activity of the Shell-embedded Pd nanoparticles was investigated. To increase the accessible active site and therefore increase the catalytic activity of noble metal nanoparticles, the in situ synthesized noble metal nanoparticles are selectively immobilized in the outer Shell Layer of the core−Shell poly(styrene-co-4-vinylpyridine) microspheres, which are synthesized by one-stage soap-free emulsion polymerization in water and contain a core of polystyrene and a coordinative Shell of poly(4-vinylpyridine). It is found the Pd nanoparticles embedded in the Shell Layer of the core−Shell micospheres are an efficient and easily reusable catalyst for Suzuki reactions performed in water.
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Synthesis of Noble Metal Nanoparticles Embedded in the Shell Layer of Core−Shell Poly(styrene-co-4-vinylpyridine) Micospheres and Their Application in Catalysis
Chemistry of Materials, 2008Co-Authors: Fei Wen, Wangqing Zhang, Guanwei Wei, Yao Wang, Jianzheng Zhang, Minchao Zhang, Linqi ShiAbstract:The noble metal nanoparticles of Pd, Au, and Ag embedded in the Shell Layer of core−Shell poly(styrene-co-4-vinylpyridine) micospheres were synthesized, and the catalytic activity of the Shell-embedded Pd nanoparticles was investigated. To increase the accessible active site and therefore increase the catalytic activity of noble metal nanoparticles, the in situ synthesized noble metal nanoparticles are selectively immobilized in the outer Shell Layer of the core−Shell poly(styrene-co-4-vinylpyridine) microspheres, which are synthesized by one-stage soap-free emulsion polymerization in water and contain a core of polystyrene and a coordinative Shell of poly(4-vinylpyridine). It is found the Pd nanoparticles embedded in the Shell Layer of the core−Shell micospheres are an efficient and easily reusable catalyst for Suzuki reactions performed in water.
Qingwen Wang - One of the best experts on this subject based on the ideXlab platform.
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High-strength, lightweight, co-extruded wood flour-polyvinyl chloride/lumber composites: Effects of wood content in Shell Layer on mechanical properties, creep resistance, and dimensional stability
Journal of Cleaner Production, 2020Co-Authors: Zong Guanggong, Xiaolong Hao, Jianxiu Hao, Tang Wei, Yiqun Fang, Qingwen WangAbstract:Abstract The defects of creep deformation and brittle fracture, which coexist in wood plastic composites (WPCs), significantly restrict WPCs as structural engineering materials. This study aims to advance WPCs via structural design and co-extrusion technology, for the development of a lightweight, high-strength, tough, creep-resistant, and water-resistant composite, for structural engineering applications. Novel wood-plastic/lumber composites (WPLCs) were fabricated with high-strength lightweight laminated veneer lumber (LVL) as a core and water-resistant wood-polyvinyl chloride composites (WPVCs) as the Shell Layer using multi-phase co-extrusion technology. The effect of wood content in the Shell Layer on flexural properties, impact strength, low-velocity impact behavior, creep resistance, and dimensional stability of the WPLCs were investigated and compared with those of LVL and WPVCs. Increasing wood content within the scope of the experiment resulted in increased flexural strength and modulus in both WPVCs and WPLCs. The flexural modulus and impact strength of WPLC containing 60 phr wood in Shell Layer (WPLC60) were significantly increased by 112.8% and 303.6%, respectively, compared with that of the corresponding WPVC60 control. Factoring in composite density, the comparison between WPLCs and WPVCs showed specific flexural modulus and impact strength of WPLC60 as 284% and 704% of the values of WPVC60, respectively. The WPLCs exhibited higher impact resistance and bending stiffness and lower absorbed energy and permanent indentation than those of LVL. The creep strain of the WPLCs decreased with increasing wood content in the Shell Layers. Specifically, the creep strain of WPLC60 was 85.8% and 28.9% of the values of LVL and WPVC60, respectively. The WPLCs almost kept their original appearance except for discoloration after nine cycles of hot water immersion. The water absorption and thickness swelling of the WPLCs were below 1.0% and considerably lower than those of the LVL and pure PVC co-extruded samples. The experimental results indicated that the novel co-extruded wood-plastic/lumber composites effectively achieved excellent performance suitable for structural engineering applications.
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Mechanical properties, creep resistance, and dimensional stability of core/Shell structured wood flour/polyethylene composites with highly filled core Layer
Construction and Building Materials, 2019Co-Authors: Xiaolong Hao, Yi Xin, Lichao Sun, Qingwen WangAbstract:Abstract To obtain an optimum balance in performance and cost, this study aims to investigate the effect of wood flour (WF) content in both Shell and highly filled core Layers on the mechanical properties, creep behavior, and dimensional stability of the resulting coextruded WF/high density polyethylene composites (Co-WPCs). Scanning electron microscopy showed good interfacial adhesion between the core and Shell Layers. The flexural strength and modulus of the Co-WPCs increased with increasing WF content in Shell Layer, while the flexural strain and impact strength decreased but still higher than those of the core-only controls. Finite element analysis showed that the coextruded flexible Shell Layer acted as a stress transferring medium avoiding stress concentration and endowed the Co-WPCs with higher toughness. Increasing the content of rigid WF in both the core and Shell Layers resulted in significant reduction in creep strain. Coating the highly filled core Layer with less filled Shell Layer can markedly reduce the water absorption and thickness swelling. For Co-WPCs with 70 wt% WF in core Layer and 20 wt% WF in Shell Layer, the flexural strength, modulus, and creep strain were comparable to those of the core-only control, but the flexural strain, impact strength, and water resistance were much better.
Mojtaba Rahimabady - One of the best experts on this subject based on the ideXlab platform.
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dielectric behaviors and high energy storage density of nanocomposites with core Shell batio3 tio2 in poly vinylidene fluoride hexafluoropropylene
Physical Chemistry Chemical Physics, 2013Co-Authors: Mojtaba Rahimabady, Meysam Sharifzadeh Mirshekarloo, Li LuAbstract:Nanocomposites comprising a P(VDF-HFP) polymer matrix and core–Shell structured nanoparticle fillers were prepared, in which a crystalline, ultrathin TiO2 Shell Layer encapsulates BaTiO3 nanoparticles. A large dielectric constant (>110) was obtained, which was unexpectedly more than 3 times higher than that of the nanocomposite without the TiO2 Shell Layer. The significant improvement in electric polarization is attributed to the highly interactive interfaces among the multiple dielectric materials with the introduction of the intermediate TiO2 Layer, which also improves the breakdown field (>340 MV m−1). Thus a resulting dielectric energy density of 12.2 J cm−3 is achieved, among the highest energy densities for polymer–ceramic composites.
Yuan-chang Liang - One of the best experts on this subject based on the ideXlab platform.
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Shell Layer Thickness-Dependent Photocatalytic Activity of Sputtering Synthesized Hexagonally Structured ZnO-ZnS Composite Nanorods
Materials (Basel Switzerland), 2018Co-Authors: Yuan-chang Liang, Chein-chung WangAbstract:ZnO-ZnS core-Shell nanorods are synthesized by combining the hydrothermal method and vacuum sputtering. The core-Shell nanorods with variable ZnS Shell thickness (7–46 nm) are synthesized by varying ZnS sputtering duration. Structural analyses demonstrated that the as-grown ZnS Shell Layers are well crystallized with preferring growth direction of ZnS (002). The sputtering-assisted synthesized ZnO-ZnS core-Shell nanorods are in a wurtzite structure. Moreover, photoluminance spectral analysis indicated that the introduction of a ZnS Shell Layer improved the photoexcited electron and hole separation efficiency of the ZnO nanorods. A strong correlation between effective charge separation and the Shell thickness aids the photocatalytic behavior of the nanorods and improves their photoresponsive nature. The results of comparative degradation efficiency toward methylene blue showed that the ZnO-ZnS nanorods with the Shell thickness of approximately 17 nm have the highest photocatalytic performance than the ZnO-ZnS nanorods with other Shell Layer thicknesses. The highly reusable catalytic efficiency and superior photocatalytic performance of the ZnO-ZnS nanorods with 17 nm-thick ZnS Shell Layer supports their potential for environmental applications.
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Microstructure-Dependent Visible-Light Driven Photoactivity of Sputtering-Assisted Synthesis of Sulfide-Based Visible-Light Sensitizer onto ZnO Nanorods.
Materials (Basel Switzerland), 2016Co-Authors: Yuan-chang Liang, Cheng-chia Chung, Chein-chung WangAbstract:The ZnO-CdS core-Shell composite nanorods with CdS Shell Layer thicknesses of 5 and 20 nm were synthesized by combining the hydrothermal growth of ZnO nanorods with the sputtering thin-film deposition of CdS crystallites. The microstructures and optical properties of the ZnO-CdS nanorods were associated with the CdS Shell Layer thickness. A thicker CdS Shell Layer resulted in a rougher surface morphology, more crystal defects, and a broader optical absorbance edge in the ZnO-CdS rods. The ZnO-CdS (20 nm) nanorods thus engaged in more photoactivity in this study. When they were further subjected to a postannealing procedure in ambient Ar/H2, this resulted in the Layer-like CdS Shell Layers being converted into the serrated CdS Shell Layers. By contrast, the ZnO-CdS nanorods conducted with the postannealing procedure exhibited superior photoactivity and photoelectrochemical performance; the substantial changes in the microstructures and optical properties of the composite nanorods following postannealing in this study might account for the observed results.
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Crystal growth and Shell Layer crystal feature-dependent sensing and photoactivity performance of zinc oxide–indium oxide core–Shell nanorod heterostructures
CrystEngComm, 2015Co-Authors: Yuan-chang Liang, Tzu-yin Lin, Chia-min LeeAbstract:ZnO–In2O3 (InO) core–Shell nanorod heterostructures were synthesized by sputtering InO crystallites on ZnO nanorods. InO Shell Layers consisting of tapered and prism-shaped InO crystallites were obtained by varying the sputtering deposition duration. The crystalline InO Layer on the ZnO nanorods was composed of small tapered InO crystallites and showed a (222) orientation. However, large prism-shaped InO crystallites on ZnO showed multiple crystallographic orientations. The InO Shell Layer consisting of prism-shaped crystallites had a larger number of crystal defects than the InO Shell Layer with a tapered morphology. Comparatively, the ZnO–InO heterostructures with a prism-shaped InO Shell Layer showed oxidizing gas sensing and photoelectrochemical performance superior to those of the heterostructures with a tapered-morphology InO Shell Layer. The difference in crystal features between the tapered and the prism-shaped InO crystallites explained the observations in this study.
