Electron Dispersive X-ray Spectrometer Research Articles

Influence of the Voltage on Pore Diameter and Growth Rate of Thin Anodic Aluminium Oxide (AAO) Pattern on Silicon Substrate

By applying dual anodization procedures of aluminum (Al) thin film over silicon substrate under controlled anodizing process conditions, a thin anodic alumina (AAO) pattern with hexagonal honeycomb-like arrangement nano-pores and highly-regular aligned arrays was created. Anodizing DC voltage was thought to have an effect on pore size dimensions. With anodizing DC voltage, the pore diameter (30 - 110nm) showed a linear change. The rate of vertical growth of the nanopores was found to be proportional to the anodizing voltage. To achieve open-through pore nanostructure and ensure homogeneous electrochemical deposition of various nanostructures onto AAO pattern, a bottommost barrier layer of the AAO pattern was detached during dropping the DC voltage in the final period of the anodization process, followed by a pore widening wet treatment for numerous minutes at ambient temperature atmosphere. The features of the AAO pattern were inspected by using the field emission scanning microscope (FESEM) linked with an electron dispersive x-ray spectrometer (EDX) for chemical elements investigation.

Nanolitography based on electrospun and etched nanofibers

In this study, we propose a new type of nanolithography procedure to fabricate orderly patterned metallic nanostructures using the electrohydrodynamic method and the reactive ion etching process. The electrohydrodynamic process parameters were tuned so as to create patterning with precision, and fibers in nanoscale on silver-coated substrates. We also studied reactive ion etching with different durations on the well-patterned samples. The experiments show that applying a voltage of 400 V resulted in straight patterned fibers with a diameter of 208.7 ± 30.3 nm. The statistical analysis on scanning electron microscope (SEM) images showed a significant difference in the diameter of the fibers fabricated at 400 V compared to those at 500 V and 600 V. We also confirm that the etching process has no affect on the fiber diameter. Moreover, electron dispersive X-Ray spectrometer (EDX) results suggest that an etching duration of 7 min is sufficient to remove the silver coating that is not covered with the fibers, and protect the silver nanostructures underneath the fibers. Utilizing a low-cost nanolithography procedure, we obtain the orderly patterned silver nanostructures for possible integration into miniaturized devices.

SiO2-kaolinite affecting the surface properties of ternary poly(vinyl chloride)/silica/kaolinite nanocomposites

The products from the dispersion of nanoscale particulates such as the layered clays or the spherical inorganic minerals within the polymeric matrices are called polymeric nanocomposites. In this paper, we prepared poly(vinyl chloride) (PVC) based nanocomposites containing SiO2-kaolinite by melt compounding. The influence of SiO2-kaolinite on the surface properties of PVC was investigated by the use of various surface analysis techniques including a ttenuated total reflectance spectroscopy (ATR), wide angle X-ray diffractometry (WAXD), atomic force microscopy (AFM), scanning electron microscopy (SEM), electron dispersive X-ray spectrometer (EDX), contact angle measurement (CAM), and reflectance spectroscopy (RS). ATR spectroscopy showed possible interaction between layered kaolinite and PVC at surface. Microscopic methods illustrated an increased surface roughness compared to the pure PVC. Contact angle measurements of the resultant PVC nanocomposites demonstrated that the wettability of substrates depends on the surface interactions between kaolinite layers and PVC matrix. Optical properties of nanocomposite films were finally measured by the aid of reflectance spectrophotometer. It can be seen from optical studies that reflectance values were increased after incorporation of SiO2-kaolinite in nanocomposite.

Composition of agglomerates in fluidized bed reactors for thermochemical conversion of biomass and waste fuels: Experimental data in comparison with predictions by a thermodynamic equilibrium model

Controlled combustion tests of biomass were performed in the 12MWth circulating fluidized bed (CFB) boiler located on the campus of Chalmers University of Technology. The aim was twofold: to investigate the composition of agglomerated material and also to highlight the reasons for sintering and agglomeration during thermochemical conversion of biomass and wastes in fluidized bed reactors using quartz sand as bed material. Bed ash from three different tests regarding fuel or fuel mixtures (wood with straw, bark, and bark with refused derived fuel) was analysed to determine the ash elements using: (a) inductive coupled plasma (ICP) equipped with optical emission spectroscopy (OES) and (b) scanning electron microscopy equipped with an electron dispersive X-ray spectrometer (SEM–EDX). Chemical equilibrium calculations were also performed to support the interpretation of the experimental findings. It was found that the combination of (i) well controlled full-scale tests in a fluidized bed boiler, (ii) the use of line-scans by the EDX spectrometer of the SEM on bed samples and (iii) thermodynamic equilibrium modelling is a powerful tool in understanding the phenomena of bed agglomeration using quartz sand.

UV radiation inducing succinic acid/silica–kaolinite network on cellulose fiber to improve the functionality

The aim of this research was to embed silica–kaolinite on a cotton surface using succinic acid (SA) as a cross-linking agent and sodium hypophosphite (SHP) as a catalyst. The influence of inorganic particles on the performance of the cellulose fiber was investigated using Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermo-gravimetric analyzer (TGA), scanning electron microscope (SEM), electron dispersive X-ray spectrometer (EDX), water contact angle (WCA) and reflectance spectroscopy (RS). ATR showed the possible interactions between silica, kaolinite, the cross-linking agent and cellulose functional groups on the surface. The results obtained from the thermal measurements demonstrated that the stabilized silica–kaolinite particles can significantly improve the thermal stability of the cotton fiber. This research suggests a successful method for stabilization and compatibility of various inorganic particles on cotton.

Photocatalytic Reaction of SiO<sub>2</sub>/TiO<sub>2</sub> Composite Core-Shell Structured Powders

In this study, SiO2/TiO2 core-shell powders were prepared by 2 steps of modified sol-gel method. Silica cores were firstly prepared. In this step, polyethylene glycol was introduced in order to control shape and size. At the second step, Zn, N co-doped TiO2 sols were prepared to coat on SiO2 cores by dipping method. The synthesized core-shell structured powders were characterized using scanning electron microscopy, electron dispersive X-ray spectrometer, X-ray diffractometer and Fourier-transformed infrared spectrophotometer. Photocatalytic activity was evaluated by means of degradation of methylene blue solution. The effect of polyethylene glycol utilized for controlling size and shape of silica cores was studied together with the effect of calcinations temperature and amount of Zn doping on anatase phase, morphology, and crystallite size and photocatalytic property. Silica cored particles are spherical shape having particle size of 300 nm. TiO2 coating resulted in a rough and textured surface of the core-shell particles and particle size about 400 nm. It was found that calcination temperature has a significant effect on degree of crystallinity of anatase phase, leading to enhancement of photocatalytic activity.

Synthesis and Characterization of Silver Immobilized on Glass Fibers

Silver nano-particles (AgNPs) films were prepared and coated on glass fibers by reduction of [Ag(NH3)2]+ complex with sucrose at temperature of 400-600°C. The effect of AgNO3 solution used as a source of silver was also investigated. The synthesized films were characterized by scanning electron microscopy (SEM), X-ray diffractometer (XRD) and electron dispersive X-ray spectrometer (EDX). It was found that both concentration and temperature have an effect on crystal growth, morphology and hydrophobic property of silver nanoparticles on surfaces of glass fibers. High temperature synthesis can partially cause grain coarsening of AgNPs on the films. The hydrophobic property of these silver coarsened grains was found to increase at the calcined temperature of 600°C, leading to easily removed from the surface coating.

Deposition of silver nanoparticles on carbon nanotube by chemical reduction method: Evaluation of surface, thermal and optical properties

Silver was stabilized on multi-walled carbon nanotubes (MWCNTs) by chemical-reduction technique using N,N-dimethylformamide (DMF) as a reducing agent. The influence of silver on the performance of carbon nanotubes (CNTs) was investigated by employing Fourier-transform infrared spectra (FTIR), Raman spectroscopy (RAS), thermal gravimetric analysis (TGA), zeta potential measurement, scanning electron microscope (SEM), electron dispersive X-ray spectrometer (EDX), transmission electron microscopy (TEM), and reflectance spectroscopy (RS). FTIR as well as RS methods evidenced the synthesis procedure using chemical reduction method was successful. Performing TGA of the samples under oxygen atmosphere demonstrated that the silver nanoparticles (Ag NPs) generated on MWCNTs surface can decrease the thermal stability of the particles by the catalytic oxidation of CNTs. In contrary, the thermal stability of the MWCNTs has improved under nitrogen atmosphere. EDX results showed the presence of Ag, Au and Co on the surface of deposited sample. The synthesised silver multi-walled carbon nanotubes (Ag–MWCNTs) were found to have higher UV reflection activity compared with untreated particles. The Ag–CNTs can be used in producing anti-UV composites.

Cr(VI) adsorption from electroplating plating wastewater by chemically modified coir pith

Coir pith samples were chemically modified by grafting with acrylic acid for the removal of Cr(VI) from electroplating wastewater. The presence of acrylic acid on the coir pith surface was verified by a scanning electron microscope with an electron dispersive x-ray spectrometer (SEM/EDX), Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TG). The carbonyl groups (C==O) from the carboxylic acids (COOH) increased on the coir pith surface after grafting with acrylic acid. In addition, the thermal stability of the acrylic acid-grafted coir pith also improved. The optimum conditions for grafting the acrylic acid on the coir pith consisted of 2 M acrylic acid and 0.00125 M ceric ammonium nitrate (CAN, as an initiator). The maximum Cr(VI) removal (99.99 ± 0.07%) was obtained with the following conditions: a 1.3% (w/v) dosage of acrylic acid-grafted coir pith, a system pH of 2, a contact time of 22 h, a temperature of 30 °C, a particle size of <150 μm and an initial Cr(VI) of 1,171 mg l(-1). At system pH of 2, Cr(VI) in the HCrO(4)(-) form can be adsorbed with acrylic acid-grafted coir pith via an electrostatic attraction. The adsorption isotherm of 2 M acrylic acid-grafted coir pith exhibited a good fit with the Langmuir isotherm. The maximum Cr(VI) adsorption capacity of the 2 M acrylic acid-grafted coir pith was 196.00 mg Cr(VI) g(-1) adsorbent, whereas for coir pith without grafting, the maximum Cr(VI) removal was 165.00 mg Cr(VI) g(-1) adsorbent. The adsorption capacity of the acrylic acid-grafted coir pith for Cr(VI) was higher compared to the original coir pith. This result was due to the enhancement of the carbonyl groups on the coir pith surface that may have involved the mechanism of chromium adsorption. The X-ray absorption near edged structure (XANES) and desorption studies suggested that most of the Cr(III) that presented on the acrylic acid-grafted coir pith was due to the Cr(VI) being reduced to Cr(III) on the adsorbent surface. FTIR confirmed the involvement of the carbonyl groups (C==O) and the methoxy groups (OCH3) in the mechanism of chromium adsorption. Thermodynamic study, such as enthalpy (ΔH), free energy (ΔG) and entropy change (ΔS) indicated that the overall adsorption process was endothermic, spontaneous and randomness. In addition, the adsorption process was favored at high temperatures.

Synthesizing tertiary silver/silica/kaolinite nanocomposite using photo-reduction method: Characterization of morphology and electromagnetic properties

Silver was loaded on silica/kaolinite by photo-reduction technique. The present study investigated the effects of the UV irradiation on different characteristics of the particles employing X-ray diffraction (XRD), Fourier-transform infrared spectra (FTIR), UV–vis spectrophotometer (UVS), Brunauer–Emmett–Teller specific surface area method (BETM), zeta potential measurement (ZPM), thermal gravimetric analysis (TGA), scanning electron microscope (SEM), electron dispersive X-ray spectrometer (EDX) and electromagnetic transition instrument (ETI). XRD, FTIR as well as UV absorption methods evidenced that synthesizing procedure was successful under UV irradiation. TGA results demonstrated that the Ag nanoparticles (AgNPs) generated on the silica/kaolinite surface can decrease thermal stability of particles due to proton delocalization of hydroxyl groups and Hofmann–Klemen effect. EDX results showed the presence of chemical elements namely Fe, Al, Si, Mg, K, Ti, Ag, Ca and Fe on the surface of tertiary nanocomposite. The synthesized silver/silica/kaolinite particles were found to have a higher electromagnetic absorption activity compared with silica/kaolinite. As a result, they can be used in polymer-based composites for preparing high performance electromagnetic interference shielding materials.

Structural, optical and electromagnetic properties of aluminum–clay nanocomposites

Aluminum pillared and exchanged bentonite particles were synthesized by the ion exchange method. The characteristics of the particles were investigated by Fourier-transform infrared spectra (FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), scanning electron microscope (SEM), electron dispersive X-ray spectrometer (EDS), reflectance spectrophotometer (RS) and electromagnetic transition instrument (ETI). FTIR spectra showed a successful incorporation of Al complexes into the clay interlayer. The TGA result demonstrated an improvement in thermal stability of the Al-pillared clay compared with the untreated particles. SEM and EDX results showed the presence of aluminum aggregates on the surface of clay. It was also found that Al ions affect electromagnetic properties of the clay particles.

Optical and electromagnetic characteristics of clay–iron oxide nanocomposites

Fe-pillared bentonite clay-based nanoadsorbent was synthesized by the thermal aging technique. The characteristics of the nanocomposite were detected by X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), thermal gravimetric analysis (TGA), scanning electron microscope (SEM), electron dispersive X-ray spectrometer (EDX), reflectance spectrophotometer (RS), and electromagnetic transition instrument (ETI). The TGA result demonstrated that the Fe particles generated on the clay surface can significantly improve the thermal stability of clay particles. The SEM and EDX results showed the presence of chemical elements of Fe, Al, and Si on the surface of clay. In this research, the successful synthesis of Fe-pillared clay nanocomposite can be concluded from the FTIR spectra.

Synthesis and characterization of novel Ag-polypyrrole@poly(styrene-co-methacrylic acid) nanocomposite particles

Novel raspberry-like Ag-polypyrrole/poly(styrene-co-methacrylic acid) (Ag-PPy/P(St-co-MAA)) colloidal nanocomposite particles were prepared by aqueous oxidative polymerization of pyrrole using AgNO 3 as the oxidant. The polymerization was carried out in the pre-synthesized polymer-emulsion of P(St-co-MAA) with emulsifier-free P(St-co-MAA) latex particles serving as both the templates and the stabilizers. Without any extra surfactants or polymer stabilizers, the polymerization proceeded steadily with the in-situ produced Ag-PPy nanocomposites depositing on the surface of the template particles. The obtained product is typical of raspberry-like morphology, whose nanostructures and compositions were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and electron dispersive X-ray spectrometer (EDS), respectively. The results confirmed that the surface of the P(St-co-MAA) latex was coated by Ag-PPy nanocomposite particles with a size range from 2 nm to 50 nm. Most of Ag nanoparticles are encapsulated by the PPy sheath or dispersed in the PPy layer.

Adsorption and visible-light-derived photocatalytic kinetics of organic dye on Co-doped titania nanotubes prepared by hydrothermal synthesis

A hydrothermal treatment combined with metal doping was employed to prepare highly porous Co-doped TiO 2 nanotubes (TNTs) for enhancement of adsorption and visible-light-driven photocatalysis capabilities of basic violet 10 (BV10) from liquid phase. The specific surface area of prepared TNTs can reach the maximal value of ∼379 m 2/g. These tubes are hollow scrolls with a typical outer diameter of about 10–15 nm, inner diameter 5–10 nm and length of several micrometers. The anatase-type of TNTs has an average Co-dopant concentration of 5 × 10 20 ions/cm 3, determined by an electron dispersive X-ray spectrometer. The adsorptive surface coverage on TNTs was found to be ca. 7.61–7.63%, showing a low affinity between BV10 molecules and TNTs. A pseudo-second-order reaction model was used to fit with the experimental data of adsorption and photocatalystic kinetic curves. The adsorption rate constant has one order higher than the photocatalytic rate constant, reflecting that the photocatalysis of the basic dye is the rate-determining step during the adsorption/photocatalysis process. These novel Co-doped TNTs are believed to be a promising candidate in a variety of photocatalysis applications because of the combination effect of a high porosity with a photocatalysis under visible illumination.

ASTM C 1260 실험에 의한 국내 골재의 알칼리-실리카 반응 팽창 특성

The concrete pavement at Seohae Expressway in Korea has suffered from serious distress, only after four to seven years of construction. The deterioration of ASR has seldom been reported per se in Korea, because the aggregate used for the cement concrete has been considered safe against alkali-silica reaction so far. The purpose of this study is to examine the expansion behavior of aggregates of Korea due to alkali-silica reaction by ASTM C 1260 standard method of the accelerated mortar bar test (AMBT), stereo microscopic analysis, scanning electronic microscope (SEM) analysis, and electron dispersive X-ray spectrometer (EDX) analysis. The results are presented as it follows. The accelerated mortar bar test (AMBT) showed that mica granite and felsite of igneous rocks, aroke, red sandstone and shale of sedimentary rocks, slate of metamorphic rock, and dendrite and quartz of mineral rock showed more expansion than 0.1% at 14 days. But, some sedimentary rocks and metamorphic rocks expanded more than 0.1% at 28 days even though they were less than 0.1% at 14 days. The mortar bars, which showed more than occurred 0.1% expansion, resulted in cracking on surface. SEM and EDX analysis confirmed that the white gel was a typical reaction product of ASR. The ASR gel in Korea mainly consisted of Silicate (Si) and Potassium (K) from the cement. The crack in the concrete pavement was caused by ASR. It seems that Korea is no longer safe zone against alkali-silica reaction.

A Case Study of Concrete Pavement Deterioration by Alkali-Silica Reaction in Korea

The concrete pavement of the Seohae Highway in Korea has suffered from serious distress, only four to seven years after construction. Deterioration due to Alkali-Silica Reaction (ASR) has seldom been reported per se in Korea, because the aggregate used for the cement concrete has been considered safe against alkali-silica reaction so far. The purpose of this study is to examine the deterioration caused by an alkali-silica reaction of concrete pavement in Korea. The investigation methods included visual inspection and Automatic Road Analyzer (ARAN) analysis of surface cracks, coring for internal cracks, stereo microscopic analysis, scanning electronic microscope (SEM) analysis, and electron dispersive X-ray spectrometer (EDX) analysis. The results are presented as follows: the crack pattern of the concrete pavement in Korea was longitudinal cracking, map cracking or D-cracking. Local areas of damage were noticed four to five years after construction. The cracks started from edges or joints and spread out to slabs. The most intensive cracking was observed at the intersection of the transverse and longitudinal joints. Where cracking was the most intense, pieces of concrete and aggregate had spalled away from top surface and joint interface area. The progress of deterioration was very fast. The reaction product of alkali-silica gel was clearly identified by its generally colorless, white, or very pale yellow hue seen through a stereo optical microscopy. The typical locations of the reaction product were at the interface between aggregate and cement paste in a shape of a rim, within aggregate particles in the cracks, and in the large void in the cement paste. Most of the white products were found at interface or internal aggregates. SEM and EDX analysis confirmed that the white gel was a typical reaction product of ASR. The ASR gel in Korea mainly consisted of Silicate (Si) and Potassium (K) from the cement. The crack in the concrete pavement was caused by ASR. It seems that Korea is no longer safe from alkali-silica reaction.