Atomic and electronic structure transformations of silver nanoparticles under rapid cooling conditions

The Mechanical Behaviors of Polyethylene/Silver Nanoparticle Composites: an Insight from Molecular Dynamics study

This research uses molecular dynamics simulation (MD) to study the mechanical properties of pristine polyethylene (PE) and its composites which include silver nanoparticles (PE/AgNPs) at two AgNP weight fractions of 1.05 wt% and 3.10 wt%. The stress-strain distribution of the tensile process shows that the embedded AgNPs can significantly improve the Young’s modulus and tensile strength of the pristine PE, due to improvements in the local density and strength of the PE near the AgNP surface in the range of 12 Å. Regarding the effect of temperature on the mechanical properties of pristine PE and PE/AgNP composites, the Young’s modulus and the strength of the pristine PE and PE/AgNP composites decreased significantly at 350 K and 450 K, respectively, consistent with predicted melting temperature of pristine PE, which lies at around 360 K. At such temperatures as these, PE material has stronger ductility and a higher mobility of AgNPs in the PE matrix than those at 300 K. With the increase of tensile strain, AgNPs tend to be close, and the fracture of PE leads to a similarity between both the Young’s modulus and ultimate strength found for the pristine PE and those found for the PE/AgNP composites at 350 K and 450 K, respectively.

Cross-sectional analysis of W-cored Ni nanoparticle via focused ion beam milling with impregnation

Tungsten and nickel bimetallic nanoparticle is synthesized by radio frequency thermal plasma process which belongs to the vapor phase condensation technology. The morphology and chemical composition of the synthesized particle were investigated using the conventional nanoparticle transmission electron microscopy (TEM) sample. A few part of them looked like core/shell structured particle, but ambiguities were caused by either TEM sample preparation or TEM analysis. In order to clarify whether a core/shell structure is developed for the particle, various methodologies were tried to prepare a cross-sectional TEM sample. Focused ion beam (FIB) milling was conducted for cold-compacted particles, dispersed particles on silicon wafer, and impregnated particles with epoxy which is compatible with electron beam. A sound cross-sectional sample was just obtained from cyanoacrylate impregnation and FIB milling procedure. A tungsten-cored nickel shell structure was precisely confirmed with aid of cross-sectional sample preparation method.