KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Settings

Subject: search.filters.subject.nanostructure

Search Results

Now showing 1 - 4 of 4
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    A comparative study on omnidirectional anti-reflection SiO2 nanostructure films coating by glancing angle deposition
    (2018-01-01)
    Prachachet, R.
    ;
    Samransuksamer, B.
    ;
    Horprathum, M.
    ;
    Eiamchai, P.
    ;
    Limwichean, S.
    Fabricated omnidirectional anti-reflection nanostructure films as a one of the promising alternative solar cell applications have attracted enormous scientific and industrial research benefits to their broadband, effective over a wide range of incident angles, lithography-free and high-throughput process. Recently, the nanostructure SiO<inf>2</inf> film was the most inclusive study on anti-reflection with omnidirectional and broadband characteristics. In this work, the three-dimensional silicon dioxide (SiO<inf>2</inf>) nanostructured thin film with different morphologies including vertical align, slant, spiral and thin films were fabricated by electron beam evaporation with glancing angle deposition (GLAD) on the glass slide and silicon wafer substrate. The morphological of the prepared samples were characterized by field-emission scanning electron microscope (FE-SEM) and high-resolution transmission electron microscope (HRTEM). The transmission, omnidirectional and birefringence property of the nanostructure SiO<inf>2</inf> films were investigated by UV-Vis-NIR spectrophotometer and variable angle spectroscopic ellipsometer (VASE). The spectrophotometer measurement was performed at normal incident angle and a full spectral range of 200 - 2000 nm. The angle dependent transmission measurements were investigated by rotating the specimen, with incidence angle defined relative to the surface normal of the prepared samples. This study demonstrates that the obtained SiO2 nanostructure film coated on glass slide substrate exhibits a higher transmission was 93% at normal incident angle. In addition, transmission measurement in visible wavelength and wide incident angles -80 to 80 were increased in comparison with the SiO2 thin film and glass slide substrate due to the transition in the refractive index profile from air to the nanostructure layer that improve the antireflection characteristics. The results clearly showed the enhanced omnidirectional and broadband characteristic of the three dimensional SiO2 nanostructure film coating.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Effects of seeding layer thickness on physical and morphological structure of Ga/F co-doped ZnO nanostructures
    (2017-01-01)
    Chongsri, Krisana
    ;
    Boonyarattanakalin, Kanokthip
    ;
    Pecharapa, Wisanu
    The effects of seed layer thickness on structural properties and morphology of Ga/F co-doped ZnO nanostructures were investigated in this work. The seed layers with various thicknesses were deposited on glass substrates by dip-coating. It is hypothesized that a certain range of seed layer thickness can significantly alter the outcomes of the morphological structure, density, and shape of the as-synthesized nanostructure products. The Ga/F co-doped ZnO nanostructures were grown on these seed layers by a hydrothermal process using Zn(NO<inf>3</inf>)<inf>2</inf>, NH<inf>4</inf>F, GaN<inf>3</inf>O<inf>9</inf> and hexamethyltetramine. The effects of seeding layer thickness on morphologies and structural properties were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), and UV-Vis spectroscopy. More detailed studies to clarify the seed layer effect on the growth of Ga/F co-doped ZnO nanostructures are further discussed.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    The microstructure length scale of strain rate sensitivity in ultrafine-grained aluminum
    (2015-04-14)
    Kammers, Adam D.
    ;
    Wongsa-Ngam, Jittraporn
    ;
    Langdon, Terence G.
    ;
    Daly, Samantha
    The mechanical properties of ultrafine-grained aluminum produced by equal-channel angular pressing (ECAP) are strongly influenced by strain rate. In this work, an experimental investigation of local strain rate sensitivity as it relates to microstructure was performed using a combination of scanning electron microscopy and digital image correlation. Uniaxial tension tests were carried out at 200 °C and strain rates alternating between 2.5 × 10<sup>-5</sup> s<sup>-1</sup> and 3.0 × 10<sup>-3</sup> s<sup>-1</sup>. The results demonstrate that the heterogeneous microstructure generated by ECAP has a strong effect on the microstructure scale strain rate sensitivity. Deformation centered at grain boundaries separating regions of banded microstructure exhibits the greatest strain rate sensitivity. Strain rate sensitivity is limited in deformation occurring in regions of microstructure composed of ultrafine grains separated by low-angle grain boundaries. The tensile specimens all failed by shear bands at 200 °C and at room temperature they failed by necking with little plastic deformation apparent outside of the neck.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    The effect of microstructure heterogeneity on the microscale deformation of ultrafine-grained aluminum
    (2014-01-01)
    Kammers, Adam D.
    ;
    Wongsa-Ngam, Jittraporn
    ;
    Langdon, Terence G.
    ;
    Daly, Samantha
    A combined approach of scanning electron microscopy and digital image correlation was used to examine microstructure-scale strain localization and active deformation mechanisms in ultrafine-grained (UFG) high purity (99.99%) aluminum processed by equal-channel angular pressing (ECAP). The results from tensile tests demonstrate a strong relationship between the heterogeneous microstructure and strain localization. The localized deformation was investigated in areas that contain significantly different microstructural features typical of ECAP processed aluminum. It was found that areas of the UFG microstructure containing primarily low angle grain boundaries deformed by dislocation slip and behaved similarly to a coarse-grained material. The greatest strain localization occurred at high angle grain boundaries (HAGBs) separating distinct microstructure regions and with median surface trace angles of approximately 26.6°. In areas of banded microstructure, shear strain localization as high as 30% and shear displacements of up to 500 nm occurred at the HAGBs separating bands, suggesting grain boundary sliding. Copyright © 2014 Materials Research Society.