The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
Gang Ouyang - One of the best experts on this subject based on the ideXlab platform.
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Surface Energy of nanowires
Nanotechnology, 2008Co-Authors: Gang Ouyang, Xin Tan, G. W. YangAbstract:An analytical model is developed for calculation of the Surface Energy of a nanowire based on thermodynamics and continuum medium mechanics. The core-shell structure and the outer Surface skin of the nanowire are considered for the one-dimensional nanostructure and contributions from chemical and structural effects to the Surface Energy are discussed. It is found that the Surface Energy of nanowires decreases with the diameter reduction, which induces the melting temperature depression of nanowires. Theoretical results are in agreement with the results of experiments and simulations.
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Thermodynamic model of the Surface Energy of nanocrystals
Physical Review B, 2006Co-Authors: Gang Ouyang, Xin Tan, Guowei YangAbstract:Combining the thermodynamics at the nanometer scale and the continuum mechanics, we established a universal and analytic thermodynamic model to elucidate the Surface Energy of nanocrystals. It was found that the Surface Energy decreases with decreasing the size of nanocrystals. The theoretical predictions were well consistent with the experimental data, implying that the thermodynamic model could be expected to be a general approach to understand Surface Energy in nanomaterials.
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Surface Energy and shrinkage of a nanocavity
Applied Physics Letters, 2006Co-Authors: Gang Ouyang, Xin Tan, Meng-qiu Cai, Guowei YangAbstract:An analytical model was developed for the size dependence of Surface Energy of a nanocavity from the perspective of thermodynamics and continuum medium mechanics. Three components of the liquidlike matrix, vaporlike cavity, and inner Surface skin of the cavity were considered for the cavity-matrix structure, and contribution from chemical and structural effects to the Surface Energy was discussed. It was found that the Surface Energy increases with the inverse of cavity size and that the cavity shrinks in size, differing from what is usually expected. It was suggested that the Surface skin be stronger than the matrix because of the bond order deficiency effect.
Göran Alderborn - One of the best experts on this subject based on the ideXlab platform.
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Effect of Surface Energy on Powder Compactibility
Pharmaceutical Research, 2008Co-Authors: Frauke Fichtner, Denny Mahlin, Simon Gaisford, Ken Welch, Göran AlderbornAbstract:Purpose The influence of Surface Energy on the compactibility of lactose particles has been investigated. Materials and Methods Three powders were prepared by spray drying lactose solutions without or with low proportions of the surfactant polysorbate 80. Various powder and tablet characterisation procedures were applied. The Surface Energy of the powders was characterized by Inverse Gas Chromatography and the compressibility of the powders was described by the relationship between tablet porosity and compression pressure. The compactibility of the powders was analyzed by studying the evolution of tablet tensile strength with increasing compaction pressure and porosity. Results All powders were amorphous and similar in particle size, shape, and Surface area. The compressibility of the powders and the microstructure of the formed tablets were equal. However, the compactibility and dispersive Surface Energy was dependent of the composition of the powders. Conclusion The decrease in tablet strength correlated to the decrease in powder Surface Energy at constant tablet porosities. This supports the idea that tablet strength is controlled by formation of intermolecular forces over the areas of contact between the particles and that the strength of these bonding forces is controlled by Surface Energy which, in turn, can be altered by the presence of surfactants.
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Effect of Surface Energy on powder compactibility.
Pharmaceutical research, 2008Co-Authors: Frauke Fichtner, Denny Mahlin, Simon Gaisford, Ken Welch, Göran AlderbornAbstract:The influence of Surface Energy on the compactibility of lactose particles has been investigated. Three powders were prepared by spray drying lactose solutions without or with low proportions of the surfactant polysorbate 80. Various powder and tablet characterisation procedures were applied. The Surface Energy of the powders was characterized by Inverse Gas Chromatography and the compressibility of the powders was described by the relationship between tablet porosity and compression pressure. The compactibility of the powders was analyzed by studying the evolution of tablet tensile strength with increasing compaction pressure and porosity. All powders were amorphous and similar in particle size, shape, and Surface area. The compressibility of the powders and the microstructure of the formed tablets were equal. However, the compactibility and dispersive Surface Energy was dependent of the composition of the powders. The decrease in tablet strength correlated to the decrease in powder Surface Energy at constant tablet porosities. This supports the idea that tablet strength is controlled by formation of intermolecular forces over the areas of contact between the particles and that the strength of these bonding forces is controlled by Surface Energy which, in turn, can be altered by the presence of surfactants.
Gang-feng Wang - One of the best experts on this subject based on the ideXlab platform.
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Size dependent yield hardness induced by Surface Energy
Extreme Mechanics Letters, 2020Co-Authors: Yue Ding, Gang-feng WangAbstract:Size dependent hardness has long been reported in nanosized indentations, however the corresponding explanation is still in exploration. In this paper, we examine the influence of Surface Energy on the hardness of materials under spherical indentation. To evaluate the ability of materials to resist indentation, a yield hardness is defined here as the contact pressure at the inception of material yield. It is found that this defined hardness is an intrinsic material property depending only on the yield strength and Poisson ratio in conventional continuum mechanics. Then, the impact of Surface Energy on the yield hardness is analyzed through finite element simulations. By using the dimensional analysis, the dependences of the yield hardness and critical indent depth at yield initiation on Surface Energy have been achieved. When the yield strength is comparable to the ratio of Surface Energy density to indenter radius, Surface Energy will alter the yield hardness and the critical indent depth. As the size of indenter decreases to nanoscale, both the yield hardness and the indent depth will increase significantly. This study provides a possible clarification to the size dependence of hardness and a potential approach to measure the yield strength and Surface Energy of solids through nanosized indentations.
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Calculation of Surface Energy density of rough Surface by atomic simulations
Applied Surface Science, 2019Co-Authors: Jun Wang, Jianjun Bian, Gang-feng WangAbstract:Abstract The presence of Surface Energy has an important effect on the physical and mechanical performance of nanoscale structures and materials. Determining the value of Surface Energy density has raised great concern in Surface science. Especially, how to estimate the Surface Energy density of curved and even stochastically rough Surfaces remains unsolved. The present paper is aimed to investigate the Surface Energy density of rough metal Surfaces by atomistic calculations. The Surface Energy densities of periodic sinusoidal Surfaces and stochastically rough Surfaces are calculated. Simulation results suggest an analytical model to determine the Surface Energy density of rough Surfaces by the Surface geometric parameters and the Surface Energy density of planar Surface.
M.h. Yoo - One of the best experts on this subject based on the ideXlab platform.
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Surface Energy anisotropy of FePt nanoparticles
Journal of Applied Physics, 2005Co-Authors: Suklyun Hong, M.h. YooAbstract:To investigate the Surface Energy anisotropy of FePt nanoparticles, we have performed self-consistent pseudopotential density-functional calculations. Wulff plots are constructed based on the calculated Surface Energy anisotropy, and these are used to analyze the structural feature in the reported high-resolution transmission electron microscopy images of FePt nanoparticles.
Xin Tan - One of the best experts on this subject based on the ideXlab platform.
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Surface Energy of nanowires
Nanotechnology, 2008Co-Authors: Gang Ouyang, Xin Tan, G. W. YangAbstract:An analytical model is developed for calculation of the Surface Energy of a nanowire based on thermodynamics and continuum medium mechanics. The core-shell structure and the outer Surface skin of the nanowire are considered for the one-dimensional nanostructure and contributions from chemical and structural effects to the Surface Energy are discussed. It is found that the Surface Energy of nanowires decreases with the diameter reduction, which induces the melting temperature depression of nanowires. Theoretical results are in agreement with the results of experiments and simulations.
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Thermodynamic model of the Surface Energy of nanocrystals
Physical Review B, 2006Co-Authors: Gang Ouyang, Xin Tan, Guowei YangAbstract:Combining the thermodynamics at the nanometer scale and the continuum mechanics, we established a universal and analytic thermodynamic model to elucidate the Surface Energy of nanocrystals. It was found that the Surface Energy decreases with decreasing the size of nanocrystals. The theoretical predictions were well consistent with the experimental data, implying that the thermodynamic model could be expected to be a general approach to understand Surface Energy in nanomaterials.
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Surface Energy and shrinkage of a nanocavity
Applied Physics Letters, 2006Co-Authors: Gang Ouyang, Xin Tan, Meng-qiu Cai, Guowei YangAbstract:An analytical model was developed for the size dependence of Surface Energy of a nanocavity from the perspective of thermodynamics and continuum medium mechanics. Three components of the liquidlike matrix, vaporlike cavity, and inner Surface skin of the cavity were considered for the cavity-matrix structure, and contribution from chemical and structural effects to the Surface Energy was discussed. It was found that the Surface Energy increases with the inverse of cavity size and that the cavity shrinks in size, differing from what is usually expected. It was suggested that the Surface skin be stronger than the matrix because of the bond order deficiency effect.
