Pecharapa, Wisanu

Preferred name

Pecharapa, Wisanu

Alternative Name

PECHARAPA, Wisanu

Pecharapa, W.

Main Affiliation

Integrated Innovative Technology

wisanu.pe@kmitl.ac.th

Now showing 1 - 10 of 15

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X-ray absorption spectroscopy analysis and magnetic properties of M-doped TiO2 nanoparticles (M=Co, Mn, Ni and Zn) prepared by co-precipitation method
(2017-08-01)
Wattanawikkam, Chakkaphan
;
Pecharapa, Wisanu
;
Ishihara, Keiichi N.
M-doped TiO<inf>2</inf> nanoparticles (M=Co, Mn, Ni and Zn) were synthesized by co-precipitation method combined with annealing at 500 °C for 2 h. X-ray diffraction (XRD) was used to identify their structural phases. X-ray absorption near edge structure (XANES) was conducted to probe the chemical state and crystal atomic structure of prepared samples. Magnetic properties of all samples were characterized by vibrating sample magnetrometer (VSM). The XRD analyses reveal that all samples crystallize in anatase tetragonal structure with no additional peaks. The XANES spectra exhibit triple pre-edge fingerprint of Ti4+ of oxidation state with six-fold octahedral coordinate structure. Co-, Ni- and Zn- K-edge results indicate that the Co, Ni and Zn ions in M-doped TiO<inf>2</inf> are in 2+ formal oxidation state. Meanwhile, Mn-doped TiO<inf>2</inf> sample contains the different oxidation states of 3+ and 4+. The amount of each oxidation state is confirmed by using linear combination fitting method. The magnetic measurement illustrates the paramagnetic behavior for Co-, Mn- and Ni- doped samples that strongly depend on the doping content and no hysteresis loop is observed in undoped and Zn-doped samples.
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Structural and Optical Properties of Mn-Incorporated BiVO4 Nanoparticles Synthesized by Sonochemical Process
(2022-01-01)
Wechprasit, Tirapat
;
Kansaard, Thanaphon
;
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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Characterization, X-ray absorption spectroscopic analysis and photocatalytic activity of Co/Zn co-doped TiO2 nanoparticles synthesized by one-step sonochemical process
(2021-10-01)
Mekprasart, Wanichaya
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Pavasupree, Sorapong
;
Jayasankar, C. K.
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Ravuri, Balaji Rao
;
Wattanawikkam, Chakkaphan
A novel one-step preparation of sonochemical method was applied to synthesize Co/Zn co-doped TiO<inf>2</inf> nanoparticles using a sonicator of 750 W, 20 kHz for 30 min at room temperature. The formation of the anatase TiO<inf>2</inf> phase for all as-prepared samples was observed from XRD results with a crystalline size in nanoscale. The use of ultrasound allowed for the successful doping of both Co and Zn into the TiO<inf>2</inf> lattice, which was confirmed by Synchrotron light including X-ray near edge structure (XANES) and Extended X-ray absorption fine structure (EXAFS) spectroscopy. Ti K-edge, Co K-edge, and Zn K-edge XANES spectra exhibited the dominating +4, +2, and +2 valence state of Ti, Co, and Zn in as-prepared samples, respectively. A detailed XANES and EXAFS data analysis give strong evidence that the Co/Zn dopants partially replace the Ti atom of the TiO<inf>2</inf> host. The Co/Zn co-doping extends the light absorption of the host to the visible region and restricts the e+/h+ recombination. The photocatalytic activity of samples was tested for degradation of Rhodamine B dye solution under visible light irradiation. The as-synthesized of the co-doped catalyst was presented as highly efficient, with 2.5 and 5 times dye degradation compared with single-doped and bare TiO<inf>2</inf>.
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A comparison of cation distribution and valence state in spinel crystal structure of zinc and nickel ferrites using the synchrotron X-ray absorption spectroscopy (XAS) analysis
(2014-07-24)
Tangcharoen, Thanit
;
Klysubun, Wantana
;
Ruangphanit, Anucha
;
Pecharapa, Wisanu
In this work, the physical structure, magnetism and local structure of zinc and nickel ferrites (ZnFe<inf>2</inf>O<inf>4</inf> and NiFe<inf>2</inf>O <inf>4</inf>) synthesized by typical sol-gel combustion method, were investigated by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). The formation of the single phase cubic spinel crystal structure and the different values of crystallite size (D), interplanar distance (d) and lattice constant (a) for all ferrite samples were evaluated by the XRD data. The VSM measurement provides the characteristic magnetic hysteresis loop (M-H) for each sample which was found to be significantly different from each other. The chemical shifts in Zn, Ni and Fe K-edges XANES spectra indicate the existence of Zn2+, Ni2+ and Fe3+ ions in these ferrites. The EXAFS spectra analyses applied to track Zn, Ni and Fe cation distribution indicate the distinct character of spinel crystal structure of both ferrites. The results exhibit that zinc ferrite is a normal spinel, while the nickel ferrite is an inverse spinel. Moreover, these EXAFS spectra analyses reveal that the distances between metal ion (Zn2+ or Ni2+) to central oxygen ion and to Fe3+ ions in the opposite lattice site for each ferrite sample are unequal which highly affect its magnetism. The overall simulated results are one of the important evidence encouraging the explanation on the paramagnetism for ZnFe<inf>2</inf>O<inf>4</inf> and the ferrimagnetism for NiFe<inf>2</inf>O<inf>4</inf>. © 2014 Taylor & Francis Group, LLC.
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Characterization of Bi-doped FAPbI3 perovskite films investigated by X-ray absorption spectroscopy
(2025-12-01)
Wechprasit, Tirapat
;
Bootchanont, Atipong
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Infahsaeng, Yingyot
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Wongjom, Poramed
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Wannapaiboon, Suttipong
A thorough investigation of perovskite structures formed through doping is essential for advancing the efficiency and stability of perovskite solar cells. In this study, Bi-doped FAPbI<inf>3</inf> perovskite films with varying Bi concentrations (0.5–2%) were fabricated using a spin-coating technique on ITO glass substrates. Then the films’ phase structure, local structure, and optical characteristics were analyzed. X-ray diffraction (XRD) analysis revealed that the pristine FAPbI<inf>3</inf> film exhibited both hexagonal and cubic phases, indicating structural instability. In contrast, Bi-doped FAPbI<inf>3</inf> films predominantly displayed a cubic perovskite structure, with a notable reduction in the XRD peak intensity corresponding to the hexagonal phase. UV–Vis spectroscopy showed that the undoped FAPbI<inf>3</inf> film had an absorption edge in the visible-near infrared range, while Bi-doping caused a redshift, indicating a reduction in the optical band gap. The calculated results show that optical band gaps decrease with increasing Bi, from a value of 1.49 (pure) to 1.43 (2% Bi) eV. X-ray absorption near edge structure (XANES) analysis confirmed the oxidation states of Pb2+ and Bi3+ ions across all samples, with Bi ions replacing Pb in the local structure. Photoluminescence (PL) measurements revealed an increased PL intensity with 1% Bi doping (7 105) compared with pristine FAPbI<inf>3</inf> (4.7 105), suggesting a reduction in carrier recombination. These findings demonstrate the potential of Bi-doping to stabilize perovskite structures with improved optoelectronic properties.
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Synchrotron X-ray absorption spectroscopy and magnetic characteristics studies of metal ferrites (metal = Ni, Mn, Cu) synthesized by sol-gel auto-combustion method
(2014-01-01)
Tangcharoen, Thanit
;
Klysubun, Wantana
;
Kongmark, Chanapa
;
Pecharapa, Wisanu
In this work, the metal ferrites MFe<inf>2</inf>O<inf>4</inf> (M = Ni, Mn, Cu) were synthesized from metal nitrate precursors by the sol-gel auto-combustion method using diethanolamine (DEA) as a potential fuel. The crystal structures of these ferrite powders were characterized by X-ray diffraction (XRD) technique confirming the complete formation of the single-phase cubic spinel crystal structure. The ferrimagnetism characteristic and the difference of the magnetic properties such as saturation magnetization (M<inf>s</inf>), remanent magnetization (M<inf>r</inf>), and coercivity (H <inf>c</inf>) for each after-calcined ferrite sample were scrutinized through the ferrimagnetic hysteresis loop (M-H) obtained from the vibrating sample magnetometer (VSM) measurement. Moreover, the cation distribution and valence state of these ferrites were investigated by the Ni, Mn, Cu, and Fe K-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra using the synchrotron radiation light source. From the XAS results, the analyses of both XANES and EXAFS spectra show the existence of accurate oxidation state for transition metal ions and the interionic distance to the nearest neighbors in the spinel crystal structure. In particular, the curve-fitting analysis of Ni, Mn, Cu, and Fe K-edge EXAFS spectra indicates that the degree of inversion in these metal ferrites is entirely different and found to be 0.2 for MnFe<inf>2</inf>O<inf>4</inf>, 0.8 for CuFe<inf>2</inf>O <inf>4</inf>, and 1.0 for NiFe<inf>2</inf>O<inf>4</inf>, which are the important information for understanding their effects on relevant magnetic properties. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Optical, dielectric and photocatalytic properties of perovskite ZnTiO3 nanoparticle synthesized by sonochemical process
(2015-07-29)
Wattanawikkam, Chakkaphan
;
Pecharapa, Wisanu
The sonochemical method was employed for synthesizing perovskite zinc titanate nanopowders. The yield powders were calcined at 600-900 °C for 2 h. High crystallinity phase of cubic ZnTiO<inf>3</inf> was obtained at calcination temperature of 600 °C while mixing phase of cubic and hexagonal was observed in the sample calcined at 700 °C. For the samples calcined at 800 and 900 °C, the hexagonal structure was dominant phase with a trace of rutile TiO<inf>2</inf> and spinel Zn<inf>2</inf>TiO<inf>4</inf> phase. X-ray absorption near edge spectroscopy technique (XANES) was used to probe crystal and local structure of the synthesized powders. The samples calcined at 700 °C exhibited the superior photocatalytic performance in decolorization of Rhodamine B dye under ultraviolet irradiation within 75 min. The dielectric permittivity and loss tangent of ZnTiO<inf>3</inf> calcined at 700 °C was found to be 20 and <10-2. Effect of calcination temperature on structural, morphology, optical, dielectric properties and photocatalytic activity were also investigated and discussed.
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Synchrotron X-ray absorption spectroscopy study of disordered cation distribution of nanosized zinc ferrite powders
(2016-01-01)
Tangcharoen, Thanit
;
Kongmark, Chanapa
;
Klysubun, Wantana
;
Pecharapa, Wisanu
The zinc ferrite (ZnFe<inf>2</inf>O<inf>4</inf>) powders of various nanoparticle sizes were synthesised at different milling times (0 to 24 h) of the as-combusted powders. The non-equilibrium site occupancy of zinc (Zn2+) and ferric (Fe3+) ions was investigated through Zn and Fe K-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra. The XRD and SEM strongly confirm the particle size of these ferrites decreasing with the increasing milling time. Compared with the bulk specimen of zinc ferrite, both XANES and EXAFS spectra of zinc ferrite powders clearly exhibit the large translocation of Zn2+ ions from the tetrahedral (A) sites to the octahedral (B) sites and the opposite translocation of some of Fe3+ ions without affecting the long-range structural order. Moreover, the curve-fitting analysis of Zn and Fe K-edge EXAFS spectra indicates that the degree of inversion increases as the particle size decreases resulting in significant differences in the magnetic behaviours.
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Nonlocal XANES pre-edge feature of FeTiO3 ilmenite-type at Ti and Fe K-edge
(2020-09-01)
Phoohinkong, Weerachon
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Boonyarattanakalin, Kanokthip
;
Mekprasart, Wanichaya
;
Pavasupree, Sorapong
;
Pecharapa, Wisanu
The pre-K-edge feature of Ti and Fe XANES of ilmenite FeTiO<inf>3</inf> were investigated. The electronic structure of FeTiO<inf>3</inf> 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(t<inf>2g</inf>) 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(e<inf>g</inf>) energy state is assigned to hybridization of Ti-3d(e<inf>g</inf>) 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(t<inf>2g</inf>) 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.
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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
;
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.

Pecharapa, Wisanu

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