Vittayakorn, Naratip

Preferred name

Alternative Name

Vittayakorn, N.

Vittayakorn, Narathip

Main Affiliation

School of Science

naratip.vi@kmitl.ac.th

Now showing 1 - 10 of 377

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A rapid synthesis of cobalt cyclotetraphosphate Co2P 4O12 at low temperature
(2013-05-01)
Boonchom, Banjong
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Vittayakorn, Naratip
The cobalt cyclotetraphosphate, Co<inf>2</inf>P<inf>4</inf>O<inf>12,</inf> was synthesized by evaporating a mixture of cobalt chloride hexahydrate, phosphoric acid and water at 70 °C, with further calcinations at 400 °C, 500 °C and 600 °C for 3 h. XRD results indicated that the Co <inf>2</inf>P<inf>4</inf>O<inf>12</inf> compounds obtained had only monoclinic phase with space group C<inf>2h</inf>6 (Z=4). From FT-IR spectra, vibrational modes corresponding to internal vibrations of the P <inf>4</inf>O<inf>12</inf>4- anion were identified. The morphologies and crystallite sizes for the Co<inf>2</inf>P<inf>4</inf>O<inf>12</inf> obtained from SEM data and X-ray line broadening showed non-uniform particles and 37-68 nm, respectively. All characterization methods showed that the monoclinic phase of Co<inf>2</inf>P<inf>4</inf>O<inf>12</inf> could be synthesized at the low temperature of 400 °C with short time consumption. The temperature was about 400 °C lower than that used in the previous synthesis method with CoCl <inf>2</inf> as reactant, and resulted in a cost-, energy-, and time-saving method. © 2012 Elsevier Ltd and Techna Group S.r.l.
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Phase formation and evolution of Cu:Zn partials in binary metal pyrophosphates Cu(2-x)Zn(x)P2O7; X ≈ 1
(2014-11-20)
Baitahe, Rattanai
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Vittayakorn, Naratip
Binary metal pyrophosphate powders were prepared by the solid state reaction method and subsequently calcined at 400, 500, 600, 700, and 800 °C in order to study Cu:Zn partial evolution to the final CuZnP<inf>2</inf>O<inf>7</inf> product. Synchrotron X-ray absorption, X-ray diffraction, Raman, FT-IR spectroscopy, and thermogravimetric analysis were used in this investigation. Phase evolution of the reaction products was investigated systemically. The results showed that complicated mixtures contributed to the reaction of synthesis temperature. The reaction comprised 3CuO·2P<inf>2</inf>O<inf>5</inf>·0.3NH<inf>3</inf>·0.2H<inf>2</inf>O, Cu<inf>2</inf>P<inf>2</inf>O<inf>7</inf>, Zn<inf>2</inf>P<inf>2</inf>O<inf>7</inf>, and Zn<inf>2</inf>P<inf>2</inf>O<inf>7</inf>·3H<inf>2</inf>O intermediates. Decreasing percentage of 3CuO·2P<inf>2</inf>O<inf>5</inf>·0.3NH<inf>3</inf>·0.2H<inf>2</inf>O intermediates was related directly to an increasing final product. Cu:Zn contents changed in Cu<inf>(2-x)</inf>Zn<inf>(x)</inf>P<inf>2</inf>O<inf>7</inf> in the temperature range of 400-600 °C, when x ≈ 1 clearly was related linearly to the reaction temperature. The final product was confirmed by EXAFS fitting spectra as solid solution between the Cu and Zn atom in the CuZnP<inf>2</inf>O<inf>7</inf> structure, and it indicated environment around metal atoms.
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Synthesis, phase formation and characterization of Co4Nb 2O9 powders synthesized by solid-state reaction
(2008-12-01)
Chaiyo, N.
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Muanghlua, R.
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Ruangphanit, A.
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Vittayakorn, W. C.
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Vittayakorn, N.
A corundum-type structure of cobalt niobate (Co<inf>4</inf>Nb 2O<inf>9</inf>) has been synthesized by a solid-state reaction. The formation of the Co<inf>4</inf>Nb<inf>2</inf>O<inf>9</inf> phase in the calcined powders was investigated as a function of calcination conditions by differential thermal analysis (DTA) and X-ray diffraction (XRD) techniques. Morphology and particle size have been determined by scanning electron microscopy (SEM). It was found that the minor phases of unreacted Co <inf>3</inf>O<inf>4</inf> tend to form together with the columbite CoNb <inf>2</inf>O<inf>6</inf> phase at a low calcination temperature and short dwell time. It seems that the single-phase of Co<inf>4</inf>Nb<inf>2</inf>O <inf>9</inf> in a corundum phase can be obtained successfully at the calcination conditions of 900°C for 60 min, with heating/cooling rates of 20°C /min. © 2008 Trans Tech Publications, Switzerland.
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Na2O-Gd2O3-Al2O3-P2O5 glass scintillator doped with Dy3+: X-rays and proton responses
(2023-01-01)
Wantana, N.
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Kaewnuam, E.
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Tariwong, Y.
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Quang, Nguyen Duy
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Pakawanit, P.
Dy3+:Na<inf>2</inf>O-Al<inf>2</inf>O<inf>3</inf>-Gd<inf>2</inf>O<inf>3</inf>-P<inf>2</inf>O<inf>5</inf> (Dy:NAGP) glasses were fabricated to investigate the capability for radiation responses. The influence of Dy<inf>2</inf>O<inf>3</inf> concentration on glass properties was studied. The density and effective atomic number of glass increased with the addition of Dy<inf>2</inf>O<inf>3</inf> content. The glasses absorbed the photons in the ultraviolet, visible light, and near-infrared region. In photoluminescence (PL) spectra, the obvious yellow emission at 574 nm and blue emission at 482 nm of Dy3+ were both generated by the direct excitation and the Gd-Dy energy transfer. The PL decay time of glasses was in the millisecond order. There was thermal quenching observed in temperature-dependent luminescence (TDL). The radioluminescence (RL) and protonluminescence (PrL) represented the emission pattern of Dy3+ similarly to PL spectra. The concentration quenching caused 0.50Dy:NAGP glass with the highest PL and RL emission intensity. The X-ray imaging of developed glass using a synchrotron light source was successfully imaged for the first time.
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Boosting sustainable hydrogen production via water splitting and urea oxidation using spinel hollow-sphere nano catalysts
(2025-10-01)
Lin, Hsin Yu
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Vasu, Dhanapal
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Tsang, Chun Han
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Hsu, Cheng Shan
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Prashanth, Gopi
In this study, spinel MgCo<inf>2</inf>O<inf>4</inf> materials were synthesized using three different techniques: freeze-drying, solid-state, and hydrothermal methods, to evaluate their structural, morphological, and electrocatalytic properties. Comprehensive characterization techniques including XRD, Raman spectroscopy, FT-IR, FESEM, HRTEM, and XPS confirmed the successful formation of phase-pure MgCo<inf>2</inf>O<inf>4</inf> with varied morphologies. Among the synthesized materials, the freeze-dried sample exhibited a well-defined hollow-sphere structure, providing abundant electroactive sites and superior electron/mass transport pathways. This morphology contributed to outstanding electrocatalytic performance. For the oxygen evolution reaction (OER), the hollow-sphere MgCo<inf>2</inf>O<inf>4</inf> catalyst demonstrated a low overpotential of 430 mV at 10 mA cm−2 and a Tafel slope of 190 mV dec−1. In addition, the same catalyst exhibited excellent activity for the urea oxidation reaction (UOR), with a Tafel slope of 95 mV dec−1 and enhanced current density under alkaline conditions. The superior UOR activity, enabled by the lower oxidation potential of urea (∼0.37 V vs. RHE), also highlights its potential for energy-efficient hydrogen production and wastewater treatment. This work establishes a scalable and cost-effective strategy to synthesize high-performance MgCo<inf>2</inf>O<inf>4</inf> hollow-sphere electrocatalysts, paving the way for their application in sustainable energy and environmental technologies.
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Phase transition, mechanical, dielectric and piezoelectric properties of perovskite (Pb1-xBax)ZrO3 ceramics
(2007-01-01)
Vittayakorn, Naratip
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Bongkarn, Theerachai
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Rujijanagul, Gobwute
(Pb<inf>1-x</inf>Ba<inf>x</inf>)ZrO<inf>3</inf> ceramics were prepared in the composition range 0.00≤x≤0.30 by the mixed oxide solid-state reaction method. The samples were kept at the calcination temperature 1000 °C for 1 h and at the sintering temperature 1300 °C for 3 h. The structural phase transitions and the dielectric properties were studied. It was found that the density of the ceramics decreases with increasing amount of Ba2+, whilst the average grain size is in the range 1-2.3 μm. The structure of as-calcined powder reveals that the fraction of the orthorhombic phase is decreasing with increasing Ba2+ content. The values of Vickers and Knoop hardness are in the range of 4.10-6.48 and 4.15-5.67 GPa, respectively. Dielectric measurements show that the antiferroelectric phase (AFE)-ferroelectric phase (FE) and the FE to paraelectric phase (PE) phase transformation temperatures decrease with increasing Ba2+ concentration. The AFE-FE phase transformation is detected for compositions 0.00≤x≤0.075. The maximum dielectric constant gradually increases with increasing composition up to x=0.20. For higher Ba2+ concentrations, the lowering of the maximum dielectric value is accompanied by a progressive broadening of the permittivity peak. The d<inf>33</inf> values of the samples increase from ∼0 to 87 pC/N with increasing Ba2+ concentration from x=0.00 to 0.30. © 2006 Elsevier B.V. All rights reserved.
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Sonochemical synthesis and characterization of copper oxide nanoparticles
(2011-01-01)
Wongpisutpaisan, Narongdet
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Charoonsuk, Piyanut
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Vittayakorn, Naratip
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Pecharapa, Wisanu
Copper oxide (CuO) nanoparticles were synthesized by a sonochemical process using copper nitrate and sodium hydroxide in the presence of polyvinyl alcohol (PVA) as a starting precursor. The precipitated product was calcined at various temperature ranging from 400-700°C. The physical microstructure and morphology of as-calcined nanoparticles were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). From XRD observation, it is evident that the high purity CuO nanoparticles were obtained by this synthesis process. It was additionally revealed that its crystallization and particle size was strongly dependent on the reaction time and calcination temperature. © 2011 Published by Elsevier Ltd.
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Investigation on ferromagnetic and ferroelectric properties of (La, K)-doped BiFeO3-BaTiO3 solid solution
(2013-05-01)
Prasatkhetragarn, Anurak
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Muangkonkad, Pantip
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Aommongkol, Parichart
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Jantaratana, Pongsakorn
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Vittayakorn, Naratip
Multiferroic materials of BiFeO<inf>3</inf>-BaTiO<inf>3</inf> solid solution have been fabricated in order to improve ferromagnetic and ferroelectric properties. The effects of La (1 mol%) and K (varied from 0.5-5 mol%) doped 0.75BiFeO<inf>3</inf>-0.25BaTiO<inf>3</inf> on phase formation, ferromagnetic and ferroelectric properties have been investigated and discussed. The rhombohedral perovskite phase of specimens was characterized by XRD technique. Fracture morphology reveals the grain growth characteristics with increasing K content. (La, K)-doped 0.75BiFeO<inf>3</inf>-0.25BaTiO<inf>3</inf> with La=1 mol% and K=3 mol% exhibits the highest remnant polarization and remnant magnetization. © 2012 Elsevier Ltd and Techna Group S.r.l.
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Physical properties and phase transitions in perovskite Pb[Zr 1-x(Ni1/3Nb2/3)x]O3 (0.0 ≤ x ≤ 0.5) ceramics
(2008-06-21)
Wirunchit, Supamas
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Laoratanakul, Pitak
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Vittayakorn, Naratip
A solid solution of lead zirconate-lead nickel niobate ceramics, Pb[Zr <inf>1-x</inf>(Ni<inf>1/3</inf>Nb<inf>2/3</inf>)<inf>x</inf>]O<inf>3</inf> (PZNN) with x = 0.0-0.5, was synthesized via the columbite precursor method. The crystal structures as well as the thermal and dielectric properties were investigated in terms of the lead nickel niobate (PNN) concentration. X-ray diffraction indicated that all samples exhibited a single-phase perovskite structure. At room temperature, Pb[Zr<inf>1-x</inf>(Ni<inf>1/3</inf>Nb <inf>2/3</inf>)<inf>x</inf>]O<inf>3</inf> is orthorhombic for a composition where x = 0, rhombohedral for the compositions where x = 0.1, 0.2 and 0.3 and pseudo-cubic for compositions where x = 0.4 and 0.5. The results of the addition of lead nickel niobate to the lead zirconate ceramic showed enhancement of the room-temperature dielectric permittivity. Lead nickel niobate substitution also led to lower transition temperatures. Furthermore, this transition from normal to relaxor FE ceramics was typified by a quasi-linear relationship between the diffuseness parameter δ<inf>γ</inf> and the PNN mole fraction x. © 2008 IOP Publishing Ltd.
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CaTiO3 induced ferroelectric phase coexistence and low temperature dielectric relaxation in BaTiO3–BaZrO3 ceramics
(2018-05-01)
Sutapun, Manoon
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Charoonsuk, Thitirat
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Kolodiazhnyi, Taras
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Vittayakorn, Naratip
The series of 0.86BaTiO<inf>3</inf>–(0.14−x)BaZrO<inf>3</inf>–xCaTiO<inf>3</inf> (abbreviated as BT–BZ–xCT) ceramics with 0.03 ≤ x ≤ 0.11 were studied to obtain high piezoelectric properties. Rietveld refinement analysis indicated that the BT–BZ–CT compositions follow a gradual rhombohedral (R) → orthorhombic (O) + R → O + tetragonal (T) → T phase transformation with increasing x. Clear evidence of the series of ferroelectric phase transitions was also found in the dielectric results. The R-O and O-T transition temperature shifted close to ambient temperature, while the Curie temperature slightly increased with increasing x. In addition to the dielectric loss peaks associated with the structural phase transitions, a broad low-temperature dielectric loss peak was detected in the R phase at T = 90-150 K. This dielectric relaxation was attributed to the domain wall freezing and fits well to the Vogel-Fulcher model with activation energy E<inf>a</inf> ≈ 60-300 meV and freezing temperature T<inf>VF</inf> ≈ 75-140 K. High piezoelectric strain coefficient (d<inf>33</inf>*) of about 1030 pm/V at 10 kV was achieved at x = 0.07, and a high Curie temperature (T<inf>C</inf>) was maintained at about 375 K.

Vittayakorn, Naratip

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