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Papers by Wandee Onreabroy

Coatings

Magnetic resonance imaging (MRI) is an imaging technique that is widely used for the identificati... more Magnetic resonance imaging (MRI) is an imaging technique that is widely used for the identification of internal organs, and for the medical diagnosis of tumors and cancer in the body. In general, gadolinium is used as a contrast agent to enhance image contrasting in MRI. In this study, chitosan-coated Co0.5Zn0.5Fe2O4 nanoparticles were synthesized using a co-precipitation method with a calcination temperature of 500 °C. The nanoparticles were then coated with chitosan and treated under an external magnetic field of 400 mT. X-ray diffractometer results showed that the chitosan-coated Co0.5Zn0.5Fe2O4 nanoparticles had a pure phase of Co0.5Zn0.5Fe2O4 at the (3 1 1) plane, with an average particle size of 26 nm. The presence of chitosan on the Co0.5Zn0.5Fe2O4 nanoparticles was confirmed by Fourier transform infrared spectroscopy, which showed the primary amine and secondary amine functional groups of chitosan. Here, coating the nanoparticle with chitosan not only prevented nanoparticle ...

2018 IEEE International WIE Conference on Electrical and Computer Engineering (WIECON-ECE), 2018

As the electric motorcycles are widely used, thus the charging system is important to be more con... more As the electric motorcycles are widely used, thus the charging system is important to be more convenient due to short driving range. Normally, there are two types of charging systems as conductive and wireless power transfer systems. Since the short driving range problem for electric motorcycle, thus wireless power transfer is necessary to study for increase of driving range with convenient charging application. In this study, 25 kHz of induction cooker was applied as transmitter part. The receiving part was designed for charging small electric motorcycle battery with maximum voltage of 60V and maximum current of 10A. As the receiving part, the design of receiving coil was studied with effect of parameters which were consisted of wire diameter, radius of receiving coil, number of turns, and number of wire per core. The results showed that decreasing of receiving coil radius brought about lower induction voltage due to characteristics of magnetic field in transmitter. The greater dia...

Japanese Journal of Applied Physics

Materials Science Forum

This study aims to provide the photocatalytic approach for treatment of some hazard air pollutant... more This study aims to provide the photocatalytic approach for treatment of some hazard air pollutants such as benzene, toluene, ethylbenzene and xylene (BTEX) under visible light. Silver doped titanium dioxide (Ag/TiO2) thin films with various molar ratios (0.01, 0.05, 0.1 and 0.2 mol) were synthesized via sol-gel method and dipped on polyvinyl chloride (PVC) sheet before curing with UV lamp. The X-ray diffractograms showed the composite of TiO2 anatase and nanosilver. The effect of silver doping on decreasing of band gap energy of TiO2 was observed from the absorption edge shift to higher wave length, analyzed by UV-visible spectrometer. The results from hydrophilicity test indicated that hydrophilicity of TiO2 thin film was increased by doping silver. The morphology of the Ag/TiO2 thin film studied by Scanning Electron Microscope equipped with an Energy Dispersive Spectrometer revealed well dispersed nanosilver on the smooth thin film. The BTEX degradation was carried out in a batch reactor with the initial concentration of mixed BTEX gas [25 ppm]. The remaining BTEX was examined by Gas Chromatography equipped with flame ionization detector. Among Ag/TiO2 thin films, the 0.1 Ag/TiO2 thin films exhibited the best performance for gaseous BTEX degradation under visible light. The maximum degradation efficiency was belong to xylene (89%), followed by ethylbenzene (86%), toluene (83%) and benzene (79%).

วารสารวิจัยและพัฒนา มจธ, 2012

Ce 3+ -doped silica glass was prepared by impregnation of Ce ions into a porous silica glass foll... more Ce 3+ -doped silica glass was prepared by impregnation of Ce ions into a porous silica glass followed by high temperature sintering in a CO reducing atmosphere. The characteristic emission of Ce 3+ 5d → 4f transition peaking around 375 nm is observed in the luminescence spectra under UV and X-ray excitation. The photoluminescence decay is governed by a few tens of nanoseconds decay time. The integral scintillation efficiency under X-ray irradiation is comparable to that of a Bi 4 Ge 3 O 12 (BGO) crystal while the light yield of about 16% of that of the BGO is obtained under γ-ray excitation.

Advanced Materials Research, Aug 20, 2014

AIP Conference Proceedings, 2009

Zn1-xCoxO (with x = 0, 0.01, 0.10 and 0.20) were synthesized by solid-state reaction method sinte... more Zn1-xCoxO (with x = 0, 0.01, 0.10 and 0.20) were synthesized by solid-state reaction method sintered at 600° C for 12 hours. The samples were studied by X-ray diffraction (XRD), optical absorption (UV-Vis) and Photoluminescence (PL). Structural analysis by Rietveld method using XRD showed that the peaks of secondary phase Co3O4 with a cubic structure were visible in the high-doped

Advanced Materials Research, 2015

Solid State Ionics, 2006

The electrical properties, microstructures and phase content of a ZnO -CoO -Bi 2 O 3 varistor hav... more The electrical properties, microstructures and phase content of a ZnO -CoO -Bi 2 O 3 varistor have been characterised. High-resolution TEM and selected area electron diffraction provided detailed information on the distribution and structure of the intergranular Bi-rich phase. Triple points between the ZnO matrix grains contained crystallites that could be indexed to tetragonal h-Bi 2 O 3 , cubic g-Bi 2 O 3 and y-Bi 2 O 3 , or corresponding isostructural ZnO-Bi 2 O 3 phases. Thin-film, 1 -2 nm grain boundaries were found to be amorphous, but for the first time, crystalline precipitates (with the h-Bi 2 O 3 type structure) were also detected in some thicker, 4 -5 nm films. D

Materials Science Forum, 2012

ABSTRACT

Advanced Materials Research, 2013

Advanced Materials Research, 2014

Materials Science and Engineering: B, 2006

The microstructures and electrical properties of ZnO-Bi 2 O 3 -CoO (ZBC), ZnO-Bi 2 O 3 (ZB) and Z... more The microstructures and electrical properties of ZnO-Bi 2 O 3 -CoO (ZBC), ZnO-Bi 2 O 3 (ZB) and ZnO-CoO (ZC) ceramics were investigated. Cobalt oxide addition could reduce bismuth loss at high sintering temperature. The same amount of cobalt within ZnO grains was found in both specimens, ZBC and ZC, suggesting that bismuth had no effect on the dissolution of cobalt in ZnO and cobalt substitution for zinc in the ZnO structure. The highest nonlinear coefficient of about 19 was found in the ZBC varistor sintered at 1000-1100 • C. For the ZC specimens, nonlinear properties could also be obtained in this sintering temperature range.

Materials Letters, 2005

Nonlinear current–voltage properties of zinc oxide-bismuth oxide varistors doped with cobalt oxid... more Nonlinear current–voltage properties of zinc oxide-bismuth oxide varistors doped with cobalt oxide were investigated. The composition of ZnO doped with 0.5 mol% Bi2O3 and 0.75 mol%CoO was prepared and sintered in two different surroundings, zinc oxide–bismuth oxide–cobalt oxide powder and alumina powder. Microstructures and element tracing were studied using scanning electron microscopy with X-ray microanalysis, electron probe microanalysis and X-ray

Journal of Materials Science, 2000

Varistors are voltage dependant resistors which are used widely in current-over-surge protection ... more Varistors are voltage dependant resistors which are used widely in current-over-surge protection circuits . The ceramics are highly resistive below a certain threshold field, but become conducting when this field is exceeded. The threshold or switching field is usually referred to as the breakdown field, E b . Immediately above E b , the relation between current and field may be expressed in terms of a power-law, J ∝ E α , where J is current density and E the applied field . The parameter α, is referred to as the nonlinearity exponent .

Ceramics International, 2012

M-type strontium ferrites, Sr 0.8 La 0.2 Fe 12 O 19 have been synthesized by conventional ceramic... more M-type strontium ferrites, Sr 0.8 La 0.2 Fe 12 O 19 have been synthesized by conventional ceramic process. The effects of lanthanum addition and sintering temperature on microstructures and magnetic properties of SrFe 12 O 19 and Sr 0.8 La 0.2 Fe 12 O 19 samples were investigated. Microstructural analysis of the SrFe 12 O 19 and Sr 0.8 La 0.2 Fe 12 O 19 specimens, sintered at different temperatures revealed that average grain sizes of SrFe 12 O 19 ferrites were larger than that of Sr 0.8 La 0.2 Fe 12 O 19 ferrite and increased with increasing sintering temperature. The X-ray diffraction (XRD) results confirmed the strontium hexagonal ferrite phase of SrFe 12 O 19 and Sr 0.8 La 0.2 Fe 12 O 19 compounds. A maximum coercivity value of 4850 Oe and maximum saturation magnetization value of 102 emu/g were obtained for the SrFe 12 O 19 ferrite sintered at 1150 8C and for the SrFe 12 O 19 and Sr 0.8 La 0.2 Fe 12 O 19 ferrites sintered at 1300 8C, respectively. The remanence (Mr) of Sr 0.8 La 0.2 Fe 12 O 19 sample sintered at 1200 8C possesses the maximum value of 60 emu/g.