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Formation of HfOxNy nanorod GLAD films growth by rapid thermal oxidation
(2023-01-01)
Phae-ngam, W.
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Prathumsit, J.
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Chananonnawathorn, C.
;
Nakajima, H.
;
Lertvanithphol, T.
In this work, the hafnium oxynitride (HfON) nanorod films on p-type silicon (Si) wafer substrate have been fabricated by reactive magnetron sputtering with glancing angle deposition (GLAD) technique, subsequently with a rapid thermal oxidation process at 500–900 °C under low-vacuum state. The crystallinity and morphology were investigated by glazing-incident X-ray diffraction (GIXRD) and field-emission scanning electron microscopy (FE-SEM), respectively. As-deposited films were amorphous nanorod films. The surface-sensitive X-ray photoelectron spectroscopy (XPS) analytical technique revealed that nitrogen atoms are increasingly replaced with oxygen atoms at the surface. The distribution of nitrogen atoms investigated by X-ray absorption spectroscopy (XAS) revealed the substitution of nitrogen with oxygen at the film surface and molecular nitrogen trapped in the film as the annealing temperature was increased.
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Structural and Optical Properties of Mn-Incorporated BiVO4 Nanoparticles Synthesized by Sonochemical Process
(2022-01-01)
Wechprasit, Tirapat
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Kansaard, Thanaphon
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Bootchanont, Atipong
;
Pecharapa, Wisanu
In this work, Mn-incorporated BiVO<inf>4</inf> nanoparticles with different Mn contents (0–5%) were synthesized by one-step sonochemical process. Structural phase of Mn-incorporated BiVO<inf>4</inf> nanoparticles was extensively carried out by X-ray diffraction technique. The XRD results show that the structural phase of BiVO<inf>4</inf> belongs to the monoclinic principal structure while the secondary phases of MnO, Mn<inf>2</inf>O<inf>3</inf>, and Mn<inf>3</inf>O<inf>4</inf> structures are noticed in Mn-loaded samples. Chemical bondings of Mn-incorporated BiVO<inf>4</inf> nanoparticles were characterized with Raman spectroscopy. Relevant chemical bondings confirm the existence of VO<inf>4</inf>3− tetrahedron and the V–O band by Raman spectra. Diffuse reflection spectroscopy and FE-SEM were employed to examine their optical and morphological properties, respectively. The results indicate that the incorporation of Mn can induce the red-shift of optical absorption edge in visible range, which can decrease the optical band gap of BiVO<inf>4</inf>. Morphology of all samples demonstrates the difference in shape of the compounds with the incorporation of Mn contents. Oxidation number and local structure of Mn-incorporated BiVO<inf>4</inf> nanoparticles were investigated by X-ray absorption spectroscopy. XAS results demonstrate that oxidation number of all elements correspond to Mn2+/Mn3+, Bi3+, and V5+ ions. The normalized Mn K-edge XANES spectra suggest that Mn atoms would not locate at the local site of Bi or V in BiVO<inf>4</inf> crystal because the specific feature of experimental spectra are inconsistent with simulated spectra, which is corresponded to XRD results indicating the formation of Mn-based oxide structures with various oxidation states.
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X-ray absorption spectroscopy analysis and photocatalytic behavior of ZnTiO3 nanoparticles doped with Co and Mn synthesized by sonochemical method
(2019-04-30)
Wattanawikkam, Chakkaphan
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Kansa-ard, Thanaphon
;
Pecharapa, Wisanu
ZnTiO<inf>3</inf> (ZTO) as a perovskite structure doped with Co and Mn were fabricated by sonochemical process. Structural phase, chemical and local atomic structure and photocatalytic activity of the synthesized samples were characterized, by X-ray diffraction, by X-ray absorption spectroscopy and Rhodamine B (RhB) dye degradation. The XRD results revealed that the mixing phases of cubic and hexagonal zinc titanate phases were found in all samples. The X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure technique (EXAFS) have been used to identify the crystal and atomic local structure of prepared samples. The Fourier transform EXAFS results of these prepared samples agreed well with the model of Co and Mn substituting at the B-site of ABO<inf>3</inf> structure together with small cluster of CoO and Mn<inf>2</inf>O<inf>3</inf> cluster. The photocatalytic activity for rhodamine b dye degradation under visible light irradiation exhibited that the doped samples had the superior degradation compared to bare-ZTO sample. The results suggest that the incorporation of transition metal ions of Co and Mn dopants is an effective way to improve the catalytic efficiency of perovskite ZTO structure. The effect of different dopant ions and dopant concentration on the structural, chemical, optical and photocatalytic activity are discussed.
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Synchrotron X-ray absorption spectroscopy study of the local atomic structures and cation ordering in perovskite- and spinel-type zinc stannate synthesized by co-precipitation method
(2015-12-15)
Tangcharoen, Thanit
;
Kongmark, Chanapa
;
Pecharapa, Wisanu
Zinc stannate nanocrystalline powders with two different crystal structures were synthesized from two different initial Zn2+/Sn4+ ratios by a simple co-precipitation method. X-ray diffraction (XRD), X-ray absorption near edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) techniques were used to investigate crystal structure, oxidation, and cation ordering of the after-calcined powders. XRD patterns clearly showed that the ZnSnO<inf>3</inf> perovskite phase was obtained using an equal initial Zn2+/Sn4+ ratio of 1:1, while a double Zn2+ excess sample (2:1) produced the pure Zn<inf>2</inf>SnO<inf>4</inf> spinel phase. The chemical shifts in Zn K- and Sn L3-edge XANES spectra supported that only Zn2+ and Sn4+ ions existed in these stannate samples. Moreover, the theoretical simulation of the Zn K-edge EXAFS experimental data also indicated a change in the cation ordering from orthorhombic, for perovskite ZnSnO<inf>3</inf>, to cubic for spinel Zn<inf>2</inf>SnO<inf>4</inf>. This is the first time that the local atomic structural characterization of zinc stannate powders derived from EXAFS analysis has been presented.
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Investigation of structural properties of CuPc/TiO2 nanocomposites
(2010-02-05)
Saributr, Chaloempol
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Makprasat, Wanichaya
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Thanomngam, Pitiporn
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Pecharapa, Wisanu
Structural properties of hybrid nanocomposites based on TiO<inf>2</inf> nanostructures and Copper phthalocyanine (CuPc) were investigated. The composites were prepared by mixing TiO<inf>2</inf> nanoparticle (TNP) and nanotube (TNT) with CuPc suspension. The precipitated composites were obtained by centrifuged and dried processes. Structural properties of the composites were evaluated by mean of Raman Spectroscopy and X-ray Absorption Fine Structure (XAFS). The results implied that CuPc has interatomic distance of C atoms in the second shell are decreased when CuPc is in the hybrid composites. © (2010) Trans Tech Publications.
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