Mekprasart, Wanichaya

Preferred name

Alternative Name

MEKPRASART, Wanichaya

Mekprasart, W.

Main Affiliation

Integrated Innovative Technology

wanichaya.me@kmitl.ac.th

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Effect of Zn:Al ratio and calcination time on structural properties of Zn-Al-O compound
(2016-01-01)
Mekprasart, Wanichaya
;
Worasawat, Suchada
;
Tangcharoen, Thanit
;
Pecharapa, Wisanu
Zn-Al-O compounds were successfully synthesized via co-precipitation method at pH 8 followed by calcination process at 900 °C. Influence of different precursor (Zn:Al) ratio and calcination time on their structural properties and formation have been investigated. Varying Zn:Al ratio was conducted at 2:1, 1:1, 1:2 and 1:4 with different calcination time at 0, 2, 4, and 6 h. Phase transformation and morphologies were characterized by X-ray diffraction and field-emission scanning electron microscope. Moreover, chemical bonding of Zn-Al-O compound was analyzed by Raman spectroscopy. The results indicated that chemical bonding between Zn-Al oxide evidentially occurred in all samples in composite form and spinel structure. In addition, the amount of Al content considerably contributes to significant aggregation in zinc aluminate (ZnAl<inf>2</inf>O<inf>4</inf>) spinel crystalline phase affirmed by XRD result. Meanwhile, SEM images reveal high crystallinity and strong formation of the compound obtained by prolong calcined period.
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Characterization and effect of calcination temperature on structural properties of spinel zinc aluminate synthesized via Co-precipitation process
(2015-06-01)
Mekprasart, Wanichaya
;
Worasawat, Suchada
;
Tangcharoen, Thanit
;
Pecharapa, Wisanu
Zinc aluminate (ZnAl<inf>2</inf>O<inf>4</inf>) nanopowders were synthesized by co-precipitation method using zinc chloride and aluminum chloride as starting precursors. The calcination temperature which was a crucial preparation factor was varied and its influence on relevant physical properties of the product was investigated. Structural properties of synthesized nanoparticles were investigated by X-ray diffraction, X-ray absorption spectroscopy, scanning electron microscope, and Raman spectroscopy. The results suggest that that ZnAl<inf>2</inf>O<inf>4</inf> in spinel structure with high crystallinity can be obtained after calcination beyond specific temperature affirmed by XRD results. Raman result indicates the correlated chemical bonding relating to the formation of ZnAl<inf>2</inf>O<inf>4</inf> structure. Meanwhile, the Zn K-edge X-ray absorption near-edge structure (XANES) spectra of these samples with different calcination temperature obtained from the synchrotron X-ray absorption spectroscopy measurement show the existence of accurate oxidation state for zinc ion (Zn2+) in the spinel crystal structure. Moreover, it is revealed that the calcination temperature has significant effect on the local environment of the zinc absorbing atoms through the interesting change of white line appearance.
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Synthesis and characterization of cubic-like zinc stannate powders prepared by co-precipitation method
(2016-01-01)
Mekprasart, Wanichaya
;
Tangcharoen, Thanit
;
Nakhanivej, Puritat
;
Pecharapa, Wisanu
Spinel-type zinc stannate (Zn<inf>2</inf>SnO<inf>4</inf>) powders were synthesized by co-precipitation method using zinc chloride and tin chloride as the precursors for Zn and Sn sources, respectively. Co-precipitation process is one of effective techniques due to non-complex system, short process time, high yield, large scale production and cost-effectiveness comparing to other methods. The influence of calcination temperature in the range of 900 °C to 1100 °C on the structure, morphologies and cation distribution were studied using various characterization techniques. A single spinel structure phase formation after-calcined powders are confirmed by X-ray diffraction (XRD) results meanwhile scanning electron microscope (SEM) showed the appearance of cubic-like shape. The aggregation of particle and strong crystallinity was distinctly increased resulting to their greater size by the effect of high calcined temperature. Moreover, the non-equilibrium site occupancy of zinc (Zn2+) and tin (Sn4+) ions was investigated through Zn K-edge and Sn L3-edge investigated by X-ray absorption (XAS) spectra via the synchrotron radiation light source. Compared with the calcined temperature sample, XANES spectra revealed that the oxidation state of Zn was +2 and Sn valence was +4 in all spinel Zn<inf>2</inf>SnO<inf>4</inf> samples which well corresponds to the theoretical values.
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Modification of dye-sensitized solar cell working electrode using TiO 2 nanoparticle/N-doped TiO2 nanofiber composites
(2014-01-01)
Mekprasart, Wanichaya
;
Suphankij, Sineenart
;
Tangcharoen, Thanit
;
Simpraditpan, Athapon
;
Pecharapa, Wisanu
Nanocomposite films of N-doped TiO<inf>2</inf> nanofibers (NFs) and commercial-grade TiO<inf>2</inf> nanoparticles Degussa (P25) were utilized as working electrode of typical dye-sensitized solar cells (DSSCs). N-doped TiO<inf>2</inf> NFs were fabricated via electrospinning method using ammonium acetate (CH<inf>3</inf>COONH<inf>4</inf>) as nitrogen source and titanium (IV) isopropoxide (TiP) in ethanol as starting precursor in combination with calcinations process. The electrospun NFs were characterized by XRD, Raman spectroscopy, XPS, SEM, and TEM. The photoelectric conversion performance of the DSSCs with composite film electrode was compared to the device using pure P25 film. The result shows that as calcination temperature increases, the anatase-to-rutile phase transformation and the fiber size reduction of NFs were observed. The energy conversion efficiency (η) of the device tends to increase with increasing calcined temperature with specific nanofiber loading content, indicating the significant enhancement in the device performance by the incorporation of the NFs. This enhancement of DSSCs may attribute to high surface area, higher light scattering and light harvesting, low charge recombination, and fast electron-transfer rate by loaded NFs. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Effect of Precursor Concentration on Physical Properties of Cube-Like Zn2SnO4 Powders Synthesized by Co-Precipitation Method
(2015-09-02)
Mekprasart, Wanichaya
;
Nakhanivej, Puritat
;
Tangcharoen, Thanit
;
Pecharapa, Wisanu
Cube-like Zinc stannate (Zn<inf>2</inf>SnO<inf>4</inf>) spinel powders were synthesized by co-precipitation method using chloride starting precursors of zinc and tin. The influence concentration of precursors on relevant physical properties of Zn<inf>2</inf>SnO<inf>4</inf> was investigated by increasing concentration of precursor material at 0.1 to 0.4 M (Zn:Sn at ratio 1:1). Structural properties of as-synthesized and Zn<inf>2</inf>SnO<inf>4</inf> crystal were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray absorption spectroscopy (XAS). The results indicate that as-prepared material without calcination process is in cubic symmetry of zinc hydroxy stannate (ZnSn(OH)6) affirmed by SEM and XRD results. Meanwhile, spinel phase of Zn<inf>2</inf>SnO<inf>4</inf> with strong crystalline and eminent cubic structure can be achieved after calcination at 1000°C. Homogenous dispersion, high crystallinity and good cubic structure of Zn<inf>2</inf>SnO<inf>4</inf> powders are occurred at higher concentration of precursors. Moreover, the oxidation state of these samples were investigated by the Zn K-edge and Sn L3-edge X-ray absorption near edge structure (XANES) using the synchrotron radiation light source. The analyses of XANES spectra revealed that the oxidation state of Zn was +2 and Sn valence was +4 in all Zn<inf>2</inf>SnO<inf>4</inf> samples, which well corresponds to the theoretical values. © 2015
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Effect of Zn:Sn ratio and calcination temperature on phase transformation of Zn-Sn-O compound
(2016-01-01)
Nakhanivej, Puritut
;
Tangcharoen, Thanit
;
Mekprasart, Wanichaya
;
Pecharapa, Wisanu
Zn-Sn-O powders were synthesized by simple co-precipitation method combined with calcination process using zinc chloride (ZnCl<inf>2</inf>) and tin (IV) chloride pentrahydrate (SnCl<inf>4</inf>·5H<inf>2</inf>O) as starting precursors of Zn and Sn in aqueous solution. The effect of precursors ratio on phase structure of Zn-Sn-O compound was investigated by varying ratio of Zn:Sn in the co-precipitation system. For the effect of calcination temperature, the as-precipitated product obtained at Zn: Sn ratio of 1:1 was calcined at different temperatures (400-900°C) to study phase transformation. Structural properties of as-precipitated and after-calcined powders were characterized by X-ray diffraction (XRD) while surface morphologies of final products were observed by scanning electron microscope (SEM), and thermogravimetric analysis (TGA) was used to study their thermal properties. The results indicate that the XRD pattern of Zn-Sn-O powders obtained at ratio of Zn greater than Sn can be assigned to mixed phase of ZnO and Zn<inf>2</inf>SnO<inf>4</inf>. On the other hand the XRD patterns of products obtained at ratio of Sn greater than Zn confirm a mixture of SnO<inf>2</inf> and Zn<inf>2</inf>SnO<inf>4</inf>. For the effect of calcination temperature, the rarely spinel phase of Zn<inf>2</inf>SnO<inf>4</inf> begin occur with mixed phase of ZnO and SnO<inf>2</inf> at the calcination temperature of 600°C and pure spinel structure can be obtained at the temperature above 900°C.

Mekprasart, Wanichaya

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