Papers by Keyword: Laser Diffraction

Abstract: Nanomaterial Cr₇₅Ni₂₅ alloy with a mean crystallite size of 8.3 nm and microstrain of 1.23% after 48h of milling was synthesized by mechanical alloying using a high energy planetary ball milling. The morphological changes and particles size were investigated by scanning electron microscopy and laser diffraction. Magnetic results were measured by Foucault currants, coercive field and residual magnetisation. Structural change during ball milling was evaluated by X-ray diffraction. It was found that the paramagnetic Cr_0.8Ni_0.2 phase with bcc structure appears for 12 h of milling.

Abstract: We demonstrated that a lamellar phase of lyotropic liquid crystal formed by liquid dishwash could assemble themselves into crystal droplets when their isotropic phase was slowly changed into lamellar phase on the glass substrate. Characterization by means of polarized optical microscopy showed that a pattern of liquid crystal droplets was developed in the thin films formed by liquid dishwash. Our laser light diffraction experiments confirmed that these liquid crystal droplets could effectively diffract the incident red light from a helium-neon laser. On the basis of the Fraunhofer diffraction equation, we derived for the diameter of liquid crystal droplets. The diameter of liquid crystal droplet is 42.517 m, and almost agreement with the graph of polarized optical microscopy.

Abstract: The laser diffractions phenomenon of surrounding bubbles of lyotropic liquid crystal formed by sodium dodecylsulfonate were investigated with polarized optical microscope and helium-neon laser, respectively. The eleven orders of diffractions can be observed when a beam of helium-neon laser is perpendicularly incident on the surrounding bubbles of lyotropic liquid crystal formed by sodium dodecyl sulfonate. The wavelength of the incident light is 633nm. And we have calculated the periodicity, p, of the grating was 0.211mm, and the small diffraction angle was 0.1146o. So we have simulated the microstructure of surrounding bubbles in the lyotropic liquid crystal formed by sodium dodecyl sulfonate.

Abstract: The alignment precision of the electron lenses is one of the most critical factors that determine overall performance of the microcolumn system including the image resolution and aberration. Since the lens apertures are usually as small as 5 ~ 300 μm, the alignment is difficult to carry out, even if the expensive and complicated aligner is used. In this work, we have developed a novel alignment method using laser diffraction pattern, with which we can easily obtain high-precision alignment. The images of Cu grid (mesh# 1000) and carbon nanotubes (200-nm diameter) taken by the microcolumn fabricated by the new alignment scheme has confirmed that the new method was very simple and useful.

Abstract: The particle size distribution is one of the important parameters for characterisation of quality of metal powders. Specific material properties such as ability to flow, reactivity as well as compressibility and its hardening potentials – hence the most important characteristics of sintered metals - are determined by the size distribution. The correct particle size distribution is the key to best product quality in atomisation processes of aluminium, milling of pure metals and other processes.