bluuebunny/crossref_metadata_2025 huggingface dataset:
Dielectric and Piezoelectric Properties of Zirconium-Doped Bismuth Sodium Titanate Ceramics
Authors: Watcharapasorn Anucha , Jiansirisomboon Sukanda
Published: March 2009

Zirconium-doped bismuth sodium titanate ceramics were prepared using the conventional processing method. X-ray diffraction analysis indicated the materials were single phase with a systematic shift due to increased unit cell size. The measured densities and grain size of the ceramic samples were found to range from 5.79-6.03 g/cm3 and 0.5-1.6 µm, respectively. The dielectric constant as a function of temperature became broader as Zr content increased. The piezoelectric constant was found to decrease with increasing Zr. Within the range of the solid solutions investigated, the materials seem to be promising for high temperature applications where stable dielectric constant is required.
Synthesis of Na0.5Bi0.5TiO3 Submicron Particles in Molten Salt
Authors: Setasuwon Paisan , Kijamnajsuk S.
Published: March 2009

Powder size is a major factor determining the characteristics of processing variables and end-products of ceramic materials. Na0.5Bi0.5TiO3 is one of the potential candidates for non-lead piezoelectric materials, synthesis of Na0.5Bi0.5TiO3 particles in molten salt was studied. Two salt systems, NaCl-KCl and Na2SO4-3K2SO4 were investigated. Only at 850°C and above, BNT was completely formed without any secondary phases in both eutectic chloride and sulfate salt. By substituting chloride with sulfate, the particle size of BNT could be greatly reduced to a few hundreds nanometer at 850°C. Submicron particles of SrTiO3 could also be synthesized in eutectic sulfate salt at 850°C, It is evident that molten salt synthesis could be employed to produce submicron particles of Na0.5Bi0.5TiO3 and SrTiO3. Molten salt synthesis is low-cost and capable to produce fine powders of various complex-oxides.
Fabrication of Barium Stannate Tatanate Ceramics via Combustion Technique
Authors: Wattanawikkam C. , Bongkarn Theerachai
Published: March 2009

The effect of firing temperatures on phase formation and microstructure of barium stannate titanate [Ba(Sn0.1Ti0.9)O3; BST10] ceramics were investigated. BST10 was synthesized via a combustion method, at various calcination and sintering temperatures. It was found that, a single perovskite of BST10 powders was obtained with a calcinations temperature of 1200 oC. The percent of the perovskite phase and the lattice parameter were increased with increasing calcination temperatures. The average particle size was increased from 0.48 to 1.69 µm by increasing the calcined temperature from 600 to 1200 oC. The average grain sizes were increased from 0.99 to 17.77 µm by increasing the sintering temperature from 1250 to 1450 oC. The maximum density and dielectric constant were observed in sintered samples at 1350 oC.
The Preparation of Barium Stannate Titanate Ceramics via Solid State Reaction Method
Authors: Bongkarn Theerachai , Khiawwangthong W.
Published: March 2009

In this work, the optimum conditions for the preparation of barium stannate titanate (Ba(Sn0.05Ti0.95)O3 ; BST5) ceramics by solid state reaction method were investigated. The samples were heated at calcination temperatures from 600 to 1200 oC for 4 h and sintering temperatures from 1250 to 1400 oC for 2 h. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were used to evaluate the optimum conditions for calcination. The phase formation was carried out by X-ray diffractometer (XRD). The microstructure was studied by using a scanning electron microscope (SEM). It was found that, a high purity of perovskite powders were obtained with a calcinations temperature at 1200 oC. The percent of the perovskite phase and lattice parameter a were increased by increasing the calcination temperatures. The average particle size was increased from 0.6 to 1.0 µm when increasing the calcination temperatures from 600 to 1200 oC. A pure cubic perovskite phase was found in all the sintered samples. The average grain size is in the range of 1.2 to 43.3 µm when increasing of sintering temperatures from 1250 to 1400 oC. The maximum of density and dielectric constant was observed in a 1400 oC sintered pellet.
Phase Formation and Microstructure of PBZT Powders Prepared via Mixed Oxide Method
Authors: Bongkarn Theerachai , Thiangchit C.
Published: March 2009

In this study, lead barium zirconate titanate [(Pb0.975Ba0.025)(Zr1-xTix); (PBZT)] powders with 0 £ x £1 were prepared via the mixed oxide method. The calcinations were performed between 800 and 1000 oC for 1 h. The phase formation and microstructure was studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that the structural phase indexed in the orthorhombic phase for x = 0. The tetragonal phase was detected in 0.25 £ x £ 1 samples. TG and DTA curves corresponded to XRD results. The SEM result indicated that the particle size of the powders were nonconsistant and ranged from ~0.5 to ~1.3 µm.
Effect of Calcination Temperatures on Microstructure and Phase Formation of Ba(Zr0.25Ti0.75)O3 Powders
Authors: Bongkarn Theerachai , Phungjitt N. , Vittayakorn Naratip
Published: March 2009

In this work, the effect of calcination temperatures on the microstructure and phase formation of Ba(Zr0.25Ti0.75)O3 (BZT) powders were investigated. The BZT powders were prepared via the solid state reaction method under various calcination temperatures. It was found that the second phases such as BaCO3, ZrO2, BaZrO3 and Ba2ZrO4 existed in samples with calcination temperature below 1200 oC. Homogeneity and a highly pure perovskite phase of the BZT powders were obtained with calcination condition at 1300 oC for 4 h. Lattice parameter a and the percentage of cubic perovskite phase tended to increase with increasing calcination temperatures. The TG-DTA results corresponded to the XRD investigation. The microstructures of calcined powders exhibited an almost-spherical morphology and had a porous agglomerated form in all samples. The average particle sizes were increased from 0.2 to 1.1mµ when calcination temperatures were increased from 800 to 1350 oC.
Assessment of Mechanical Properties and Transformation Behavior of Locally-Made Ni-Ti Alloys Used in Orthodontics
Authors: Chiranavanit Nattiree , Khantachawana Anak , Anuwongnukroh N. , Dechkunakorn Surachai
Published: March 2009

Ni-Ti alloy wires have been widely used in clinical orthodontics because of their properties of superelasticity (SE) and shape memory effect (SME). The purpose of this study was to assess the mechanical properties and phase transformation of 50.7Ni-49.3 Ti (at%) alloy (NT) and 45.2Ni-49.8Ti-5.0Cu (at%) alloy (NTC), cold-rolled with various percent reductions. To investigate SE and SME, heat-treatment was performed at 400°C and 600°C for 1 h. The specimens were examined using an Energy-Dispersive X-ray Spectroscope (EDS), Differential Scanning Calorimeter (DSC), Universal Testing Machine (Instron), Vickers Hardness Tester and Optical Microscope (OM). On the three-point bending test, the superelastic load-deflection curve was seen in NTC heat-treated at 400°C. Furthermore, NT heat-treated at 400°C with 30% reduction produced a partial superelastic curve. For SME, no conditions revealed superelasticity at the oral temperature. Micro-hardness value increased with greater percentage reduction. The average grain size for all specimens was typically 55-80 µm. The results showed that locally-made Ni-Ti alloys have various transformation behaviors and mechanical properties depending on three principal factors: chemical composition, work-hardening (the percent reduction) and heat-treatment temperature.
Determination of Mn Site in BaTiO3 by X-Ray Absorption Spectroscopy
Authors: Yimnirun Rattikorn , Tangsritrakul Jirapa , Rujirawat Saroj , Limpijumnong Sukit
Published: March 2009

In this work, an experimental X-ray Absorption Spectroscopy (XAS) measurement was employed to determine the local structure of Mn in BaTiO3. Synchrotron X-ray absorption near-edge structure (XANES) experiments were performed on Mn-doped BaTiO3 samples. The BaTi0.8Mn0.2O3 powders were used for the XAS experiment. XAS spectra at the Mn K-edge were recorded in transmission mode. The spectra were collected at ambient temperature with a Ge(111) double crystal monochromator and recorded after performing an energy calibration. The features of the measured Mn K-edge XANES were consistent with Mn on the Ti site and inconsistent with Mn on other sites. The clear agreement was the strongest evidence of Mn substituting for Ti in BaTiO3.
Effect of Platinum Impregnation on ZnO Tetrapods for Ethanol Sensor
Authors: Hongsith Niyom , Choopun Supab
Published: March 2009

Platinum impregnated ZnO tetrapods were prepared and studied for the detection of ethanol vapor. ZnO tetrapods were synthesized by oxidation reaction technique by heating a mixer of zinc powder (99.99%) and hydrogen peroxide solution (30 wt.%) at 1,000oC in air. Platinum was impregnated by dropping hydrogen hexachloroplatinate (IV) hydrate, H2Cl6Pt.aq, solution with different concentration on ZnO tetrapods and then, heated at 350oC for 1 hr. The platinum impregnated ZnO tetrapods were characterized by field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS) for morphology and chemical composition, respectively. The particles were observed on the surface of ZnO tetrapods. The EDS spectrum suggested that the particles were platinum. Platinum impregnated ZnO tetrapods were tested ethanol sensing properties under ethanol concentration of 50-1,000 ppm. The ethanol sensing results indicated that the sensitivity of the sensors depended on the platinum impregnated concentration. Moreover, the sensors based on platinum impregnated ZnO tetrapods of 0.035 wt.% exhibited higher sensitivity compare to those of non-impregnation ZnO tetrapods.
Structural and Optical Study of Nano-Structured CdS-CBD Thin Films on CdTe Substrates Grown by Various Temperatures Deposited
Authors: Suwattanaphiboon C. , Suttisiri N. , Hoonnivathana Ekachai , Kunsombat C.
Published: March 2009

Cadmium sulphide (CdS) thin films have been deposited by chemical bath deposition method (CBD) on CdTe substrates. The temperature of the deposition was varied from 40 oC to 70oC under stirring, pH of complexing agent about 10-11.5 and doping by CdCl2. The morphology was composed of small columnar crystals, characterized by SEM. The crystallographic structure contains a mixture of hexagonal and cubic structures were study by TEM. The energy gap values 2.395 eV were found calculated by reflectance spectra using UV-VIS spectrometer. This study showed the correlation of deposition temperature, grain size, energy gap and observed some properties of CdS nanocrystal in the films.
Transparent Glass Ceramics from 65LiNbO3-35SiO2 Glass Composition
Authors: Prapitpongwanich Pattamaporn , Harizanova Ruzha , Rüssel Christian , Pengpat Kamonpan
Published: March 2009

Transparent glass with composition 65LiNbO3-35SiO2 was fabricated via the conventional melt-quenching technique. Glass-ceramics containing nanoscale (less than 100 nm) rhombohedral lithium niobate crystals were successfully produced by annealing the respective glass at various temperatures (600, 650 700 and 975 °C) for 1 h. The result of optical transmission spectra shows that the quenched sample is optically transparent. Transparent samples should possess crystals << 200 nm and have a narrow distribution of crystal sizes.
Structural and Optical Properties of Zn0.8Co0.2O Ceramics
Authors: Sujinnapram S. , Onreabroy Wandee , Nantawisarakul T.
Published: March 2009

The Zn0.8Co0.2O ceramics were synthesized by the solid state reaction method with the mixture of ZnO and CoO powders. The mixed powders were sintered at 1200 °C and 1300 °C for 4 hours. It was found that the X-ray diffraction patterns of Zn0.8Co0.2O ceramics were similar to that of the pure ZnO one. The crystal structure of Zn0.8Co0.2O ceramics were then determined using the Rietveld full-profile analysis method to indicate a single phase with a wurtzite-like structure. Their microstructures were examined using the scanning electron microscopy. The results showed that their grain sizes were increased with increasing both the sintering temperatures and the doping effect. Moreover, the optical absorption spectra using UV-Vis spectrometer showed that there were several extra absorption bands appearing in the Zn0.8Co0.2O samples. This confirms that Co2+ is substituted Zn2+ in the wurtzite structure.
Effect of WC Addition on Phase Formation and Microstructure of TiC-Ni Composites
Authors: Wora-uaychai Nawarat , Poolthong Nuchthana , Tongsri Ruangdaj
Published: March 2009

In this research, titanium carbide-nickel (TiC-Ni) composites, with tungsten carbide addition, were fabricated by using a powder metallurgy technique. The TiC-Ni mixtures containing between 0-15 wt. % tungsten carbide (WC), were compacted and then sintered at 1300°C and 1400°C, respectively. The phase formation and microstructure of the WC-added TiC-Ni composites have been investigated by X-ray diffraction and scanning electron microscopy techniques. Mechanical properties of these composites were assessed by an indentation technique. The X-ray diffraction patterns showed no evidence of tungsten rich phases in the sintered WC-added cermets. This indicates that during the sintering process, tungsten carbide particles were dissolved in metallic binder phase (Ni phase) via dissolution/re-precipitation process during liquid phase sintering. The liquid phase formed during sintering process could improve sinterability of TiC-based cermets i.e., it could lower sintering temperatures. The TiC-Ni composites typically exhibited a core-rim structure. The cores consisted of undissolved TiC particles enveloped by rims of (Ti, W)C solid solution phase. Hardness of TiC-Ni composites increased with WC content. Sintering temperature also had a slight effect on hardness values.
Thermoplastic Polyurethane (TPU) Honeycomb Air Cushion Combined with Polylactic Acid (PLA) Nonwoven Fabric for Impact Protection
Authors: Lee Cho Hsun , Lou Ching Wen , Hsing Wen Hao , Tsai I.J. , Lin Jia Horng
Published: March 2009

Honeycomb structures are widely used in various engineering fields, including construction, the auto industry, packaging, the aerospace industry, medicine, and sports. The hexagon cells generate excellent structures and reduce material waste. Honeycomb structures have very good mechanical properties and are low cost. Nonwoven fabric is widely used in many applications because the manufacturing process for nonwoven fabric is easy and fast. In this study, Polylactic Acid (PLA) nonwoven fabric and Thermoplastic Polyurethane (TPU) honeycomb air cushion (TPU-HAC) materials were combined in a sandwich structure for impact protection. The PLA fibers and low-melting-point PLA fibers were used as raw materials to create PLA nonwoven fabric. The PLA fibers and low-melting-point PLA fibers were mixed at weight ratios of (10%, 20%, 30%, 40%, 50%). The mixed fibers were processed using needle punching and thermal bonding to create PLA nonwoven fabric. Additionally, the TPU-HACs were layered to generate various thicknesses (2/8/10 mm, 4/6/10 mm, 6/4/10 mm, 8/2/10 mm). The layered TPU-HAC materials was clamped between two PLA nonwoven fabrics to form a sandwich structure. Impact resistance was assessed using a falling- weight impact-resistance machine. Experimental findings indicate that impact resistance of the sandwich structure of the TPU-HAC materials improved when thin TPU-HAC material was placed on the thick TPU-HAC material. This study demonstrates that the sandwich structure of TPU-HAC materials as excellent impact absorption.
Investigation of Aluminium Diffusion into an Amorphous Silicon Thin Film at High Temperature by In Situ Spectroscopic Ellipsometry
Authors: Luangtip W. , Rotbuathong S. , Chindaudom P. , Horphatum M. , Patthanasetthakul V. , Eiamchai P. , Srikirin Toemsak
Published: March 2009

This work is to study the diffusion of Al into amorphous silicon (a-Si) thin film at the elevated temperature by in-situ Spectroscopic Ellipsometry (SE). The sputtered a-Si film 60 nm thick on an optically opaque Al (100 nm) layer on silicon wafer was heated in a temperature controlled heating sample stage from room temperature to 300°C and slowly cooled down to room temperature while the dynamic SE data were measured. It was found that the ∆ and Ψ spectra began to change quickly at 200°C until the temperature reached 250°C, then continue to changed very slowly until 300°C. No significant change could be observed while the sample was cooling down to room temperature. The full spectral SE measurements were also taken at every 50°C steps and used to model the diffusion of Al into the top a-Si film. The interface layer due to diffusion was modeled by Bruggeman Effective Medium Approximation (EMA) theory as the mixture of Al and Si.
Self-Cleaning Properties of TiO2 Films Deposited by Reactive Magnetron Sputtering Using Smooth D.C. and Pulsed D.C. Source
Authors: Pudwat S. , Rakkwamsuk P. , Damrongrattana S.
Published: March 2009

he TiO2 films were prepared by reactive smooth d.c. and pulsed d.c. magnetron sputtering on glass slide substrates. A metallic titanium target was reactively sputtered in a mixture of argon and oxygen. The influence of smooth d.c. and pulsed d.c. discharge power on films thickness, crystallinity, surface morphology, photocatalytic activity (methylene blue degradation) and hydrophilic activity were studied. At pulsed d.c. sputtering, plasma generator has been used to provide the asymmetric pulsed d.c. bias of the target at 100 kHz and pulsed off-time 4016ns. The structures of the films at 100nm and 300nm thick showed nano-grain size structure. The pulsed d.c. mode deposition exhibited a considerably lower surface roughness, but higher grain size compared to the films deposited with the smooth d.c. mode. At film thickness about 300 nm, the XRD peaks indicated that the dominant structure was anatase for which the preferred orientation was in (101) plane. It did not show any definite change of phase between the films deposited in the smooth d.c. mode and the film deposited in the pulse d.c. mode. For the photocatalytic activity, it was clearly seen that the films deposited by smooth d.c. mode showed a higher photocatalytic activity. The hydrophilic activity test, after the films had been irradiated by an ultraviolet light source for 30 min., the smooth d.c. mode films (thickness 300 nm) showed that a water contact angle can be less than 10°. In this study, the TiO2 films of smooth d.c. mode sputtering could be applied for a self-cleaning glass application.
Fabrication of Ferroelectric Bismuth Titanate Glass-Ceramic by Incorporation Method
Authors: Pengpat Kamonpan
Published: March 2009

In this work the fabrication of glass-ceramics containing ferroelectric BIT crystals was carried out by incorporation method. The BIT powder was prepared by conventional ceramic method with calcination temperature of 800°C. In order to prepare bismuth titanate glass ceramic by incorporation method, the BIT powder was mixed with 25 - 95 mol% B2O3 as a glass former. The batches were melted in an air atmosphere using an electric furnace, at 1150°C for 15 minutes. After that, the melts were quenched between the stainless steel plates at room temperature. It was found that crystallization of unexpected Bi2Ti4O11 phase occurred in most of the glass – ceramics with the amount of B2O3 less than 70 mol%. This may cause from the evaporation of Bi2O3 during melting. Besides, glass could only be obtained from the melt of 80 mol% B2O3 batch. In this glass, however, the small amount of TiO2 crystals was detected using SEM technique. The glasses with the amount of B2O3 more than 80% shows severe phase separation and crystallization of TiO2 and B2O3. The glasses of 80 mol% B2O3 composition were subjected to heat – treatment processes at 300 to 500°C. It was found that the crystallization of Bi2Ti4O11 phase occurred at 500°C while at 300°C and 400°C the glasses were still amorphous. The maximum dielectric constant (er) of the heat treated glass ceramics was found in the range of 22 – 30.
Attosecond Pulse and Beyond Generation Based on Multi-Stage Micro Ring Resonators
Authors: Mitatha S. , Dejhan K. , Chaiyasoonthorn S. , Yupapin P. Preecha
Published: March 2009

We firstly propose the simple system of an attosecond light pulse generation by using a soliton pulse circulating in the integrated micro ring devices. The ultra short pulse in the atto scale regime and its beyond can be easily generated. Simulation results obtained have shown that the generation of a very narrow pulse and sharp tip is achieved. In principle, light pulse known as soliton pulse is input into a three stage micro ring resonators, where the ring radii are within the range from 5-15 microns. With some selected parameters such as ring radius, coupling ratio and nonlinear refractive index, the attosecond pulse is generated and achieved. The potential applications of using such a narrow pulse for new generation optical lithography, high density CD writing, high resolution interferometer, surface roughness and high speed optical computing, quantum computing are discussed.
Chitosan Clad Manganese Doped Zing Sulphide Nanocrystallites for Biolabeling
Authors: Baruah S. , Tumcharern Gamolwan , Dutta Joydeep
Published: March 2009

The synthesis of fluorescent nanocrystals is receiving a lot of attention for potential application in biological labeling as well as phosphors for field emission devices. Zinc sulphide doped with manganese (ZnS:Mn2+) is one of the most efficient electroluminescent phosphor displaying a wide emission band centred around 590 nm resulting from the intra-ionic transition in Mn2+ ions. We report a unique synthesis of zinc sulphide nanoparticles doped with manganese using a biocompatible passivating agent ‘chitosan’, with bright luminescence peaking at 590 nm. This high luminescence efficiency of the synthesized nanocrystals are ideal for quantum dot based bio-labeling applications. Synthesis of the nanoparticles was carried out by precipitation reaction in aqueous media of zinc acetate and sodium sulphide where manganese acetate was added as the dopant. The obtained nanoparticles were around 4 to 6 nm in size and were found to be stable for months of shelf life. The photoluminescence intensity did not degrade when the colloid was heated up to 65 oC for prolonged periods.
Electrical Characterization of Diamond-Like Carbon Films Synthesized by Plasma Enhanced CVD Technique
Authors: Paosawatyanyong Boonchoat , Honglertsakul K. , Rujisamphan N. , Bhanthumnavin Worawan
Published: March 2009

Diamond-like carbon (DLC) films have been deposited on silicon substrates using microwave plasma enhanced chemical vapor deposition (PE-CVD) process of CH4 in H2 gas mixture. The well-faceted good quality DLC film with distinct diamond Raman spectroscopic characteristics are found at low CH4 concentration. Schottky barrier diode (SBD) structures are fabricated onto the grown DLC films using Ti/Au and Al as ohmic and rectifying contacts, respectively. The responses of DLC-SBD to DC and time varying signals have been studied. The frequency dependent response results are compared to models, which includes as input parameters the depletion and bulk regions resistances and capacitances trap effects, and SBD parameters of which extracted from the DC I-V characteristics. It is found that the frequency dependent properties of DLC-SBD can be associated with deep trap states inside the DLC material rather than with only the SBD geometrical structure.
Niobium and Antimony-Modified Titanium Dioxide/Epoxy Thin Film for Proton Exchange Membrane Fuel Cell
Authors: Kuanchaitrakul Tanita , Chirachanchai S. , Manuspiya H.
Published: March 2009

Inorganic Mesoporous Membrane is a new alternative to improve high-temperature fuel cell performance in proton exchange membrane fuel cells (PEMFCs) to substitute for Nafion. It possess high porosity and high specific surface areas, resulting in high proton conductivity. In this study, niobium-modified titania and antimony/niobium-modified titania ceramic were prepared via the sol-gel technique. The various contents of antimony, 0 to 3 wt%, and 3% niobium are incorporated into titania to improve the porous surface condition of the ceramic particles. The xerogels were heated at about 500°C. Inorganic membranes were prepared by using the spin-coating technique using epoxy resin as a binder. The physical, chemical, and electrical properties of these membranes were investigated. The XRD and Raman results showed that pure TiO2 and doped TiO2 nanoparticles obtained possess an anatase structure with mesoporosity. The specific surface area of the doped TiO2 was higher than that of pure TiO2 and it is worth pointing out that the doping of antimony affected the surface areas more than the doping of niobium in TiO2. Moreover, these membranes were also tested to evaluate their potential use as an electrolyte in PEMFC by using impedance spectroscopy, TGA, mechanical properties and water uptake.
Microstructure and Characterizations of Portland-Bottom Ash-Silica Fume Cement Pastes
Authors: Wongkeo W. , Thawornson W. , Chaipanich Arnon
Published: March 2009

This research investigated the microstructure and characterization of Portland-bottom ash-silica fume cement pastes. Bottom ash, a by – product from coal-fired thermal power plants, was obtained from Mae Moh power plant, Lampang, Thailand. It currently exists as waste approximately 1.5 MT per year and has not been put to use. Unlike its counterpart, fly ash, which is recognized as an alternative material used to replace part of Portland cement. Silica fume, a nanomaterial from ferrosilicon industry, is nanoparticle and highly amorphous. It is highly pozzolanic reaction and could improve properties of Portland-bottom ash cement pastes. Thus, this research investigated the effect of silica fume on microstructure and characterization of Portland-bottom ash-silica fume cement pastes. The ratios of bottom ash used to replace Portland cement were 0, 10, 20 and 30 percent by weight and silica fume was added at 5 and 10 percent by weight. Compressive strength test was then carried out. SEM and TGA were used to study the microstructure of Portland-bottom ash-silica fume cement pastes. The results show that, the compressive strength of Portland-Bottom ash-silica fume cement pastes increased with added silica fume at 5 and 10 percent. SEM micrographs show C-S-H gel and silica fume around the cement particle in Portland-bottom ash-silica fume cement pastes which gives a highly dense and less porous microstructure. TGA graphs show Ca(OH)2 decreased with silica fume content.
Investigation of Nanomaterials Prepared by Thermal Evaporation of Carbon-ZnO Mixtures
Authors: Polsongkram D. , Kasian P. , Limsuwan Pichet , Tipparach Udom , Samran S. , Chow Lee , Pukird Supakorn
Published: March 2009

ZnO and other nanomaterials were synthesized by thermal evaporation process by carbon assisted method using powder ZnO as a precursors at temperature 1200 oC in one atmosphere of nitrogen for 3 hours. The diameter of nanofibers and nanowires vary from 50 nm to 200 nm and length of several ten micrometers. The size of nanorods vary from 20 nm to 100 nm and length of a few micrometers. The stereo microscope with an image analyzer and scanning electron microscope instruments are used to characterize these nanostructured materials.
Synthesis and Characterization of Nanostructured Materials Prepared from SiO2 and GeO2 Mixture by Carbon Assisted Method
Authors: Chamninok Pattanasuk , Kasian P. , Limsuwan Pichet , Tipparach Udom , Samran S. , Chow Lee , Pukird Supakorn
Published: March 2009

Nanostructured materials were synthesized by thermal evaporation process using silicon dioxide and carbon from coconut shell charcoal or graphite mixed with GeO2 by the ratio of 5:1:1 at temperature 1200 oC in one atmosphere of nitrogen for 3 hours. The nanostructured materials were characterized by the stereo microscope (image analyzer) and scanning electron microscope. The diameters of nanowires vary from 10 nm to 50 nm and length of several 10 micrometers. Length of nanorods was around 15 micrometers and diameters vary from 10 nm to 100 nm.
Zn2TiO4 Nanostructures Prepared by Thermal Oxidation Method
Authors: Santhaveesuk T. , Wongratanaphisan D. , Mangkorntong N. , Choopun Supab
Published: March 2009

Zn2TiO4 nanostructures were synthesized by the thermal oxidation method. Zn with 0, 10, 20, and 30 mol% TiO2 mixed powder were blended in polyvinyl alcohol and coated on an alumina substrate to form thick films. The thick films were heated at temperature of 600, 700, and 800°C under normal atmosphere for 24 hrs. FE-SEM images showed belt-liked nanostructures with the length of 0.3-30 µm, the width of 30-1800 µm, and the thickness ranging in the order of nm. Ti was incorporated into the nanostructures with ZnO to form Zinc titanate compound, indicated by EDS. Raman spectra and XRD results suggested that phase of Zinc titanate is cubic Zn2TiO4. The oxidation temperature and TiO2 content are critical to the phase quality of the nanostructures.
Fabrication of Gold Nanocubes by the Electrochemical Method
Authors: Huang Chien Jung , Chiu Pin Hsiang , Wang Yeong Her , Chen Kan Lin
Published: March 2009

This paper demonstrates synthesis of gold nanocubes with uniform size about 30 nm by a simple electrochemical method. The surfactant cetyltrimethylammonium bromide (CTAB) and tetradodecylammonium bromide (TTAB) were used as the stabilizer and micelle template to control the size and shape of gold nanocubes. In this study, acetone solvent was injected to the electrolyte solution with surfactant, changing the surfactant micelle-template, leading to the formation of gold nanocubes. The gold nanocubes have a surface plasmon resonance (SPR) band at a wavelength of about 530 nm. The gold nanodumbbells have been determined to be single-crystalline with a face-centered cubic (fcc) structure by X-ray diffraction (XRD) analysis.
Synthesis of Gold Nanodogbones by the Seed Mediated Growth Method with Addition of Vitamin C Solvent
Authors: Chiu Pin Hsiang , Huang Chien Jung , Wang Yeong Her , Chen Chern Hwa
Published: March 2009

A simple seeded mediated growth (SMG) method with addition of vitamin C solvent to prepare novel gold nanodogbones is reported. In SMG method, gold nanodogbones are produced in reasonable yield by chemical reducing HAuCl4 in surfactant solution, with small seed gold particles added as nucleation centers for the preparation of large size nanoparticles. Besides, the surfactant absorbs strongly (as a bilayer) along the crystal face of the nanoparticle. The surfactant is usually considered to be a soft micelle-template, which controls the size and shape of the nanoparticles. In this study, the role of vitamin C is found to alter gold nanoparticles shape from rod structures to dogbone-like structures. The aspect ratio of gold nanodogbones can be easily controlled by addition amount of vitamin C solvent from 10 to 30 µL.
Chiral Helices in a 3D Network of Zn2(en)V2O7 (en = Ethylenediamine)
Authors: Krachodnok S. , Haller K.J. , Williams I.D.
Published: March 2009

An inorganic-organic hybrid vanadate complex, Zn2(en)V2O7 (en = ethylenediamine) has been hydrothermally synthesized and characterized by single-crystal X-ray crystallography, TG analysis, IR spectroscopy, and elemental analysis. The title compound crystallizes in the monoclinic space group P21 with a = 7.0885(7), b = 8.6040(9), c = 8.1869(8) Å, b = 112.224(2)° and V = 462.22(8) Å3, T = 298±2 K and R1[I>2s(I)] = 0.0291 for 2170 observed reflections. The structure consists of undulating sheets constructed from helical chains that share Zn coordination centers with repeating units propagated into a helix by the two-fold screw axes at 0, y, ½ and pillared with alternating VO4 tetrahedra to generate a 3D chiral network. Neighboring helices are interconnected by µ2-O bridges to form the three-dimensional network. The strength of the network is reinforced by hydrogen bonding. TG analysis shows thermal stability of the network up to 283 °C.
Chemical Resistant Improvement of Natural Rubber and Nitrile Gloves by Coating with Hydrophobic Film
Authors: Atthi N. , Nimittrakoolchai O. , Jeamsaksiri W. , Supothina Sitthisuntorn
Published: March 2009

In this paper, we report innovative gloves that are coated with hydrophobic film such that the outer surface of the gloves is hydrophobic. A coating precursor containing polymethyl hydrogensiloxane, silica nanoparticle, semifluorinated silane and Pt-catalyst was painted onto the gloves. The coated gloves were kept at room temperature for 12 h to make the film dry, and then tested for their chemical resistance with 10 M NaOH, conc. HCl, conc. H2SO4 and conc. HNO3 solutions, as well as the standard buffered solutions (pH = 1, 4, 10, and 12) at 25oC by dropping the chemicals onto the coated gloves. It was found that the nitrile gloves had similar contact angles to the latex gloves when tested with the standard buffered solutions while the nitrile gloves had higher contact angles compared to the latex gloves when tested with different aqueous-based hazardous chemicals. The nitrile gloves coated with the hydrophobic film showed high acid droplet contact angle, leaving behind much lesser damage from hazardous chemicals.
Effect of Nano-Porous Alumina Filler on Thermal and Electrical Transport Properties of Solid Polymer Electrolyte (PEO)12LiBF4
Authors: Pitawala H.M.J.C. , Dissanayake M.A.K.L. , Seneviratne V.A. , Mellander B.E. , Albinsson I.
Published: March 2009

onic conductivity, dielectric and thermal properties of (PEO)12LiBF4 solid polymer electrolyte, dispersed with nanoporous Al2O3 have been studied. Out of seven different compositions studied, the (PEO)12LiBF4 polymer-salt complex showed the highest conductivity with σ25 oC = 8.27 × 10-6 S cm-1. Dispersion of different weight ratio of nano-porous alumina fillers to this electrolyte showed that the composite electrolyte composition with 15 wt. % Al2O3 gave the highest conductivity with σ25 oC = 6.05 × 10-5 S cm-1. The glass transition temperature, Tg decreased from -35.3 oC to -43.2 oC and the PEO crystallite melting temperature, Tm decreased from 64.5 oC to 58.8 oC due to the incorporation of 15 wt. % Al2O3 filler, suggesting that the interaction between the PEO backbone and the Al2O3 filler have affected the main chain dynamics of the host polymer. As the presence of the filler results in an increased conductivity mainly due to an increased amount of amorphous phase in the electrolyte above Tm, another mechanism, directly associated with the filler particles, appears to contribute to the observed conductivity enhancement. A possible mechanism for this could be the creation of additional hopping sites and favorable conducting pathways for migrating ionic species though Lewis acid-base type interactions between ionic species and O/OH sites on the filler grain surface. Results of the dielectric relaxation spectroscopy agree with the suggestion that the increased mobility is largely responsible for the obtained conductivity enhancement caused by the nano- porous filler.
Surface Treatment of Polystyrene Films with Inductively Coupled Plasma System
Authors: Nakhowong R. , Srikhirin Toemsak , Osotchan Tanakorn
Published: March 2009

The surface of polystyrene (PS) thin films in argon plasma was modified to study the hydrophilicity properties. An inductively coupled plasma (ICP) system was used to generate the argon plasma. In the experiment, the effect of RF power levels, gas flow rate and treatment time was investigated. The surface morphology of PS films was examined by the atomic force microscopy (AFM), also the contact angle goniometry was used for measuring the wettability of PS films before and after plasma treatment. After the plasma treatment, AFM images of PS revealed the increasing of the surface roughness as increasing the power levels and treatment times. Moreover, after treated with argon plasma, the contact angles of polystyrene films also decrease where the power levels and treatment times were increased. It is clear that the effects of power levels and treatment time improve the wettability of PS films. It can also be observed that by placing the sample in air after plasma treatment, the contact angle gradually increases probably due to moisture absorption in the PS films.
Ring-Opening Polymerization of ε-Caprolactone Using Novel Tin(II) Alkoxide Initiators
Authors: Kleawkla A. , Molloy Robert , Naksata W. , Punyodom Winita
Published: March 2009

Two novel tin(II) alkoxides, namely: tin(II) hexoxide, Sn(OC6H13)2, and tin(II) octoxide, Sn(OC8H17)2, have been synthesized for use as coordination-insertion initiators in the bulk ring-opening polymerization of ε-caprolactone. The kinetics of the polymerization reactions were studied at 140 °C by dilatometry. It was found that both alkoxides were slow to dissolve in the ε-caprolactone monomer due to their molecular aggregation in the solid state. As a result, the slow solubilization of the initiators gave rise to deviations from the expected first-order kinetics. Instead, the kinetic results adhered more closely to zero-order kinetics with apparent zero-order rate constants k0 of 6.58 x 10-2 and 4.63 x 10-2 mol l-1 min-1 for the hexoxide and octoxide respectively
Extraction of Defect in Doping Silicon Wafer by Analyzing the Lifetime Profile Method
Authors: Pengchan W. , Phetchakul T. , Poyai Amporn
Published: March 2009

The total leakage current in silicon p-n junction diodes compatible with 0.8 µm CMOS technology is investigated. The generation lifetime is a key parameter for the leakage current, which can be obtained from the current-voltage (I-V) and the capacitance-voltage (C-V) characteristics. As will be shown, the electrically active defect from ion implantation process generated in p-n junction can be extracted from the generation current density.
Effect of Palladium on Photocatalytic Activity of SnO2 Nanoparticles
Authors: Janmanee R. , Pirakitikulr P. , Wetchakun Natda , Liewhiran Chaikarn , Phanichphant Sukon
Published: March 2009

SnO2 nanoparticles were successfully synthesized with either the presence (PS) or absence (NPS) of the Broussonetia papyrifera (L.) Vent Pulp as the dispersant by the precipitation coupling with the thermal decomposition methods using tin tetrachloride pentahydrate (Sn4Cl.5H2O) and ammonium hydroxide (NH4OH) as the starting material and precipitant respectively. The pulp was soaked in SnCl4 solution and NH4OH was slowly added dropwise. The white gelable precipitate of Sn(OH)4 was obtained. Afterward, the white precipitate was filtered and washed until it was free from chloride. The white precipitate was then dried at 80°C for 24h and calcined for 1h at 600°C, 650°C, and 700°C respectively. The synthesized products were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and Brunauer-Emmett-Teller (BET) measurement of specific surface area. The crystallite sizes of SnO2 nanoparticles with the presence and absence of the pulp were found to be ranging from 5-15 nm and 5-30 nm respectively. The specific surface areas (SSABET) were 62.53 m2/g and 26.60 m2/g for PS and NPS samples respectively. SnO2 nanoparticles were doped with palladium in the range from 0.25-1.00 mol% by the impregnation method. The photocatalytic activity of SnO2 and Pd-doped SnO2 nanoparticles were investigated for the degradation of sucrose and glucose under UVA-light irradiation. The results showed that the photocatalytic activity of Pd-doped SnO2 was higher than pure SnO2 and the best photocatalytic activity for the degradation of sucrose and glucose were obtained in the case of Pd-doped SnO2 nanoparticles with 0.5 mol % and 1.0 mol % Pd loading respectively.
Simple Thermoelectric Module
Authors: Kumpeerapun T. , Scherrer Hubert , Kosalathip V. , Sripichai I.
Published: March 2009

The short-time-consumption melting and hot pressing processes were used to synthesize n-type and p-type Bi-Sb-Te thermoelectric materials. The synthesis materials were characterized and used for the module fabrication. The aluminium substrate was used instead of alumina substrate because it is easy to cut and to avoid fragility of the module. The performance of 20 x 20 mm2 prototype thermoelectric module consists of 7 pairs of n-type and p-type Bi-Sb-Te thermoelectric materials was investigated and then compared its performance to 40 mm x 40 mm commercial module. The output power densities as a function of temperature difference across the devices and open circuit voltages from the module are reported.
Sulphate-Based Flame-Retardant for Handmade Mulberry Paper
Authors: Naksata W. , Naksata Manoch
Published: March 2009

Handmade mulberry paper was coated with flame retardants reagent: ammonium sulphate, at the various concentrations. The properties of mulberry paper, i.e. rate of water absorption, rate of flammability, flash point and mechanical properties expressed as Young’s modulus were studied. Mulberry paper coated with sulphate-based compound was not flammable and the rate of water absorption was decreased, while the elasticity was increased.
Hydrothermal Synthesis of Zinc Oxide (ZnO) Microparticle
Authors: Pookmanee Pusit , Khuanphet S. , Phanichphant Sukon
Published: March 2009

Zinc oxide (ZnO) microparticle was synthesized by hydrothermal route using zinc acetate and ammonium hydroxide as the starting precursors in the mole ratio of 1:6. The final mixture solution was adjust with pH of 9 and treated in PTFE-line autoclave at 100 oC for 2, 4 and 6 h. The precipitate was washed with deionized water until the final pH solution of 7 and then dried at 100 oC for 4h. The phase structure was examined by X-ray diffraction (XRD). A single phase hexagonal structure was obtained without calcination step. Microstructure was investigated by scanning electron microscopy (SEM). The particle size of ZnO was in the range of 0.15-1.5 µm with irregular in shape. The chemical composition was identified by energy dispersive X-ray spectroscopy (EDXS). The elemental composition of ZnO showed the characteristic X-ray energy value as follows: zinc of Lα = 1.012 keV, Kα = 8.630 keV and Kβ = 9.570 keV and oxygen of Kα = 0.525 keV, respectively.
Enhancement of the Photocatalytic Performance of Ru-Doped TiO2 Nanoparticles
Authors: Wetchakun Khatcharin , Wetchakun Natda , Phanichphant Sukon
Published: March 2009

Pure TiO2 nanoparticles were synthesized by the modified sol-gel method using titanium tetraisopropoxide (TTIP) precursor dissolved in absolute ethanol. A pouch type cellophane membrane was employed as barrier between the precursor solution and the mixture of absolute ethanol (1:1 v/v) and distilled water with 0.5-1.0 % concentrated of ammonia in order to fix the reaction activity inside the pouch and control diffusion rate of hydrolysis and condensation reaction. The doping of TiO2 nanoparticles with 0.1, 0.2, 0.5, 1.0 and 2.0 at.% Ru was performed by the impregnation method using ruthenium acetyl acetonate in toluene as dopant. The properties of the all samples were characterized by X-ray diffraction (XRD), Brunauer, Emmett and Teller (BET)-specific surface area, Scanning electron microscopy-Energy dispersive spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). The crystalline size of pure TiO2 and Ru-doped TiO2 nanopaticles were found to be in the range of 10-20 nm. The photocatalytic mineralization of formic acid, oxalic acid, sucrose and glucose was investigated using Degussa P25, pure TiO2 and Ru-doped TiO2 nanoparticles as photocatalysts in aqueous solutions under UVA irradiation. The rate of 50% mineralization of formic acid by 0.1 at.% Ru-doped TiO2 was 1.53 times and 1.34 times higher than that of pure TiO2 and Degussa P25, respectively showing the enhancement of the photocatalytic performance of TiO2 by doping with an optimum amount of ruthenium.
Synthesis, Phase Formation and Characterization of Co4Nb2O9 Powders Synthesized by Solid-State Reaction
Authors: Chaiyo N. , Muanghlua R. , Ruangphanit A. , Vittayakorn Wanwilai C. , Vittayakorn Naratip
Published: March 2009

A corundum-type structure of cobalt niobate (Co4Nb2O9) has been synthesized by a solid-state reaction. The formation of the Co4Nb2O9 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 Co3O4 tend to form together with the columbite CoNb2O6 phase at a low calcination temperature and short dwell time. It seems that the single-phase of Co4Nb2O9 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.
Effects of Potassium Fluoride Salt Additive on the Sintering Temperature and Dielectric Properties of BaFe0.5Nb0.5O3 Ceramics
Authors: Intatha Uraiwan , Sathitada K. , Eitssayeam Sukum , Pengpat Kamonpan , Rujijanagul Gobwute , Thavornyuttakarn P. , Tunkasiri Tawee
Published: March 2009

BaFe0.5Nb0.5O3 (BFN) exhibits very high dielectric constant over a wide temperature range. However, these materials normally require high-temperature sintering to achieve a maximum densification. The aim of this study is to determine the effect of potassium fluoride salt on the sintering and dielectric properties of BFN ceramics. The results show that KF additive lower the sintering temperature by 100-200°C without affecting the formation of BFN phase. Ceramics doped with 1% KF show optimum densities of about 95% of the theoretical value when sintered at 1300°C. The addition of fluoride salt in the BFN ceramics causes very broad dielectric constant curves over a wide temperature range indicating the diffuse phase transition characteristic. Furthermore, this addition also reduces in the dielectric loss when compared with pure BFN ceramics
Effect of ZrO2 Doping in Physical Properties of Barium Iron Niobate Ceramics
Authors: Intatha Uraiwan , Eitssayeam Sukum , Pengpat Kamonpan , Rujijanagul Gobwute , Tunkasiri Tawee
Published: March 2009

In this work, preparation conditions and effect of ZrO2 doped BaFe0.5Nb0.5O3 ceramics were studied. Relationship between structure and dielectric properties was investigated. Single-phase cubic BFN powder was synthesized by solid-state reaction at 1200°C for 4 hours with heating and cooling rate of 5°C/min. Various amount of ZrO2 doped from 0.1 to 0.5 %weight were used for doping. After that BFN ceramics were formed via uniaxial pressing and sintered at 1300°C for 4 hours with heating and cooling rate of 5°C/min. Physical properties, microstructure, phase evolution and dielectric properties were studied to find out the optimum conditions for high voltage capacitor applications.
Influence of Structural and Electrical Properties of ITO Films on Electrochromic Properties of WO3 Films
Authors: Aiempanakit K. , Dumrongrattana Supattanapong , Rakkwamsuk P.
Published: March 2009

Indium tin oxide (ITO) films had been deposited on glass substrate without substrate heating and then tungsten oxide (WO3) films were deposited on ITO films by DC magnetron sputtering. In this work, we present the annealing ambient effect of ITO substrate on electrochromic properties of WO3 films. The ITO films were annealing in air and in vacuum at 350°C before coating with WO3 films. The structural, optical, and electrical properties of ITO films for as-deposited, annealing in air and in vacuum were investigated by X-ray diffraction, UV-VIS-NIR spectroscope and four point probe. The ITO films had a better crystallinity and lager grain size after annealing in air and in vacuum. The resistivity of ITO films increase with annealing in air, but decrease with annealing in vacuum. The WO3 films show difference surface morphology with higher grain size and surface roughness when coating on annealed ITO films in both cases. The electrochemical properties of film systems were characterized by cyclic voltammetry. The film systems of ITO plus WO3 showed that the charge capacity of ITO substrate annealing in vacuum was higher than the as-deposited ITO substrate and the ITO substrate annealing in air, respectively. This result corresponded to electrical conductivity of each ITO substrate.