Browsing by Author "Wisanu Pecharapa"

Now showing 1 - 3 of 3
  • Default Image
    Item
    Nonlocal XANES pre-edge feature of FeTiO3 ilmenite-type at Ti and Fe K-edge
    (Elsevier Ltd, 2020) Weerachon Phoohinkong; Kanokthip Boonyarattanakalin; Wanichaya Mekprasart; Sorapong Pavasupree; Wisanu Pecharapa; W. Pecharapa; College of Nanotechnology, King Mongkut's Institute of Technology Ladkrabang, Ladkrabang, 10520, Thailand; email: kpewisan@gmail.com
    The pre-K-edge feature of Ti and Fe XANES of ilmenite FeTiO3 were investigated. The electronic structure of FeTiO3 was examined based on the partial density of electronic state distribution on both local and nonlocal atoms. A strong contribution of nonlocal metal-metal intervalence electronic states of Ti and Fe pre-K-edge was observed in X-ray absorption near-edge structure (XANES) measurement. This observation agrees well with the calculated local state density. The nonlocal excitation transitions in the pre-edge feature contribute to local pre-K-edge at both Ti and Fe. Ti pre-K-edge consists of highly hybridized Ti-3d(t2g) with a small part of dipole-allowed 4p and a small 4s density transition state feature which is predominated by nonlocal of Fe-3d mixed with 4p state delocalized via O-2p as the main component peak. The peak feature at Ti-3d(eg) energy state is assigned to hybridization of Ti-3d(eg) and Ti-4p state contributed with nonlocal of the hybridized Fe-sp and the Ti-pd state. Fe pre-K-edge shows two main prominent transition peaks of hybridized Fe-pd state and the delocalized local Fe-sp with nonlocal Ti-3d(t2g) and 4p mixing states centered at 7112.38 and 7116.48 eV, respectively. The local and nonlocal excited transition energy states and density of both Ti pre-K-edge and Fe pre-K-edge features are corresponded with each other through the O-2p state transition pathway. © 2020 Elsevier Ltd
  • Default Image
    Item
    Optical absorption and FTIR study of cellulose/tio2hybrid composites
    (Chiang Mai University, 2019) Kittiya Plermjai; Kanokthip Boonyarattanakalin; Wanichaya Mekprasart; Weerachon Phoohinkong; Sorapong Pavasupree; Wisanu Pecharapa; W. Pecharapa; College of Nanotechnology, King Mongkut�s Institute of Technology Ladkrabang, Bangkok, 10520, Thailand; email: kpewisan@gmail.com
    Cellulose/TiO2 composite was prepared by conventional mixing using distilled water as medium. The structure and relevant properties of cellulose/TiO2 composite were characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and UV- Vis spectroscopy. XRD results exhibit typical cellulose structure type I. The absorbance spectra of TiO2and cellulose exist in vicinity of 200 nm and 350 nm in the UV range, corresponding to the UV-C, UV-B and UV-A. In addition, the UV absorption band of the composite can be extended covering wide UV region. Corresponding FTIR results suggest the existence of chemical bonding or surface interaction between TiO2 and cellulose. � 2019, All Right reserved.
  • Default Image
    Item
    Synthesis and characterization of copper zinc oxide nanoparticles obtained via metathesis process
    (IOP Publishing Ltd, 2017) Weerachon Phoohinkong; Tita Foophow; Wisanu Pecharapa; W. Pecharapa; College of Nanotechnology, King Mongkut's Institute of Technology Ladkrabang, Bangkok, 10520, Thailand; email: p_veerachon@hotmail.com
    Copper-doped zinc oxide nanoparticles were successfully synthesized by grinding copper acetate and zinc acetate powder with different starting molar ratios in combined with sodium hydroxide. The effect of initial copper and zinc molar ratios on the product samples was investigated and discussed. Relevant ligand coordination type of reactant acetate salt precursors and product samples were investigated by Fourier transform infrared spectroscopy (FTIR). The particle shapes and surface morphologies were characterized by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Phase structures of prepared samples were studied by x-ray powder diffraction (XRD) and x-ray absorption near-edge spectroscopy (XANES) was applied to investigate the local structure of Cu and Zn environment atoms. The results demonstrate that the, particle size of as-synthesized products affected by copper concentration in the precursor trend to gradually decreases from nanorod shape with diameter around 50-100 nm to irregular particle structure around 5 nm associated with an increase in the concentration of copper in precursor. Moreover, it is noticed that shape and morphology of the products are strongly dependent on Cu:Zn ratios during the synthesis. Nanocrystallines Cu-doped ZnO by the substitution in Zn site with a high crystallization degree of hexagonal wurtzite structure were obtained. This synthesis technique is suggested as a potential effective technique for preparing copper zinc oxide nanoparticles with various atomic ratio in wide range of applications. � 2017 Vietnam Academy of Science & Technology .