Biomedical subjects

Minghui Song

Publications and source records attributed to Minghui Song.

4 recordsLinked to original sources

PubMed2005

Growth of tungsten nanodendrites on SiO2 substrate using electron-beam-induced deposition.

Tungsten nanodendrite structures were fabricated on an insulator SiO2 substrate using an electron-beam-induced deposition process in a high voltage transmission electron microscope. The effect of electron beam accelerating voltage on the nanodendrite structures was investigated. The morphologies and their growth rates did not have obvious difference for the deposition at accelerating voltages from 400 to 1000 kV. A mechanism for the growth and morphology of the nanodendrite structure was proposed involving charge-up produced on the surface of the substrate, movement of charges to and accumulation at the convex surface of the substrate and the tips of the deposits. High-energy electron irradiation enhanced diffusion of W atoms in the nanodendrites, promoted crystallization of W grains, so that more crystallized W nanodendrite structures were achieved by the electron-beam-induced deposition process using higher energy electron beams.

Dendrites↗

PubMed2004

Detection of iron-oxide layer on the surface of iron nitride using high-resolution electron microscopy and Fourier filtering.

High-resolution electron microscopy (HREM) was used to detect the surface Fe3O4 iron-oxide layer formed on [011] Fe4N iron nitride due to electron irradiation in the transmission electron microscope. The existence of a surface oxide layer was confirmed by both image processing and through-focus observation. Images of the iron oxide were revealed using the process of fast Fourier transformation (FFT) of experimental HREM images, filtering of the FFT patterns and inverse FFT. By through-focus observation, HREM images of iron oxide were obtained based on the tuning of contrast transfer function. Fourier filtering is effective for examining the beginning of phase transformation, because at this stage the diffraction spots of iron oxide are too weak to be detected. At the time when the iron oxide layer has developed to some extent, through-focus observation is useful to obtain an image of oxide layers.

Journal Article↗

PubMed2004

Electron microscopy observation of interface in diffusion-bonded copper joint.

The microstructure at the interface of diffusion-bonded joints of oxygen-free high-conductivity copper for two kinds of surface conditions, with and without argon ion bombardment treatment, was investigated using scanning and high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy. The results showed that argon ion bombardment effectively removed the surface oxide film layer and lowered the height of the surface asperity, so that inclusion formation was decreased and void shrinkage time was shortened at the interface of the bonded copper joints, and the tensile strength of diffusion-bonded copper joints was improved obviously.

Journal Article↗

PubMed2002

Ordering in a fluid inert gas confined by flat surfaces.

High-resolution transmission electron microscopy images of room-temperature fluid xenon in small faceted cavities in aluminum reveal the presence of three well-defined layers within the fluid at each facet. Such interfacial layering of simple liquids has been theoretically predicted, but observational evidence has been ambiguous. Molecular dynamics simulations indicate that the density variation induced by the layering will cause xenon, confined to an approximately cubic cavity of volume approximately 8 cubic nanometers, to condense into the body-centered cubic phase, differing from the face-centered cubic phase of both bulk solid xenon and solid xenon confined in somewhat larger (>/=20 cubic nanometer) tetradecahedral cavities in face-centered cubic metals. Layering at the liquid-solid interface plays an important role in determining physical properties as diverse as the rheological behavior of two-dimensionally confined liquids and the dynamics of crystal growth.

Journal Article↗