• Carbon letters
• /
• v.10 no.1
• /
• pp.5-8
• /
• 2009

We measured the non-carbon content of single-walled carbon nanotubes (SWCNTs) in SWCNT soot using thermogravimetric analysis. The weight increased percentage by the oxidation of metal in the raw soot is well obtained by TGA graph which was confirmed with ICP-AES, XRD, and XPS. This work will be very useful for the purity precise evaluation of SWCNT with UN-vis-NIR spectroscopy.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2011.10a
• /
• pp.32.1-32.1
• /
• 2011

Ultra thin tantalum nitride (TaNx) films with various thicknesses (10 nm to 40 nm) have been deposited by rf magnetron sputtering technique on glass substrates. The as deposited films were systematically characterized by several analytical techniques such as X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, atomic force microscopy, UV-Vis-NIR double beam spectrophotometer and four point probe method. From the XRD results, the as deposited films are in amorphous nature, irrespective of the film thicknesses. The films composition was changed greatly with increasing the film thickness. SEM micrographs exhibited the densely pack microstructure, and homogeneous surface covered by small size grains at lower thickness deposited films. The surface roughness of the films was linearly increases with increasing the films thickness, consequently the transmittance decreased. The absorption edge was shifted towards higher wavelength as the film thickness increases.

• Journal of the Korean Ceramic Society
• /
• v.29 no.1
• /
• pp.48-52
• /
• 1992

Indium tin oxide (ITO) layers are of considerable interest on account of the combination of properties they provide high electrical conductivity, high infrared reflection with high solar energy transmission, high transmission in the visible range. We are concerned about the variation of the spectral transmittances and sheet resistances as the thickness of SiO2-ZrO2 barrier layer and ITO layers and heat treating conditions are changed. Transmittances and reflectivities were studied by measuring UV-VIS-NIR-, FT-IR spectroscopy. ITO films are crack free, homogeneous and of polycrystalline cubic structure. The microstructure of good ITO films shows a narrow grain size distribution and mean value of 100 nm. The selectivity of absorbing properties is improved by increasing the thickness of ITO films. The increase of sheet resistance of ITO films are due to the increase in the reaction between films and glass substrate.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.9
• /
• pp.1729-1731
• /
• 2008

Colloidal solutions of crystalline PbSe nanoparticles have been synthesized by hot solution chemical process using PbO in oleic acid and tributylphosphine (TBP) bonded selenium. The use of TBP as a capping agent along with oleic acid gives a very good yield (around 10% at 180 ${^{\circ}C}$) with an average diameter of particle of about < 6.6 nm. The effects of temperature on size and production yield of PbSe quantum dots are studied. Xray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and UV/VIS/NIR absorption spectroscopy were used to characterize the samples.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.286.2-286.2
• /
• 2013

기존의 이온성 고분자-금속 복합체(IPMC)는 백금(Pt)전극을 이온성 전기활성 고분자(Ionic electroactive polymer)인 나피온에 무전해 도금으로 만들어졌다. 본 연구는 백금전극을 그래핀으로 대체하여 투명 이온성 고분자-그래핀 복합체(IPGC)를 제작하였다. 그래핀은 근적외선 화학기상증착법(NIR-CVD)으로 전이금속 (Cu, Ni) 위에 탄화수소 가스(CH4)를 이용하여 성장하였다. 전이 금속위에 성장된 그래핀을 나피온 양쪽면에 van der Waals 결합력을 이용하는 습식 전이공정으로 전극을 형성하였다. IPGC는 면 저항(4-point probe), 투과도(UV/Vis spectrometer) 및 라만 분광법(Micro Raman spectroscopy)의 측정으로 그래핀 전극의 특성평가를 하였고, 전계방사 주사전자현미경(Field Emisson Scanning Electron Microscope; FE-SEM)을 사용하여 IPGC의 구조적 특성을 확인하였다. 제작된 IPGC의 성능은 백금전극을 이용한 IPMC의 변위(displacement), 힘(force), 작동 주파수(Operating frequency) 분석을 통해 비교 평가하였다.

• Journal of Powder Materials
• /
• v.19 no.3
• /
• pp.177-181
• /
• 2012

Copper composite materials have attracted wide attention for energy applications. Especially $CuInS_2$ has a desirable direct band gap of 1.5 eV, which is well matched with the solar spectrum. $CuInS_2$ nanoparticles could make it possible to develop color-tunable $CuInS_2$ nanoparticle emitter in the near-infrared region (NIR) for energy application and bio imaging sensors. In this paper, $CuInS_2$ nanoparticles were successfully synthesized by thermo-decomposition methods. Surface modification of $CuInS_2$ nanoparticles were carried out with various semiconductor materials (CdS, ZnS) for enhanced optical properties. Surface modification and silica coating of hydrophobic nanoparticles could be dispersed in polar solvent for potential applications. Their optical properties were characterized by UV-vis spectroscopy and photoluminescence spectroscopy (PL). The structures of silica coated $CuInS_2$ were observed by transmission electron microscopy (TEM).

• Journal of the Korean Ceramic Society
• /
• v.52 no.5
• /
• pp.384-388
• /
• 2015

We prepared blocking layers by adding 0.0 ~ 0.6 wt% nano diamond blends (DBs) to $TiO_2$ blocking layers to improve the energy conversion efficiencies (ECEs) of dye sensitized solar cells (DSSCs). TEM and micro-Raman spectroscopy were used to characterize the microstructure and phases of DBs, respectively. Optical microscopy and FE-SEM were used to analyze the microstructure of the $TiO_2$ blocking layer with DBs. UV-VIS-NIR spectroscopy was used to determine the absorbance of the working electrodes. A solar simulator and a potentiostat were used to determine the photovoltaic properties and the impedance of the DSSCs with DBs. From the results of the DBs analysis, we determined a 6.97 nm combination of nano diamonds and graphite. We confirmed that ECE increased from 5.64 to 6.48 % when the added DBs increased from 0.0 to 0.2 wt%. This indicates that the effective surface area and electron mobility increased when DBs were added to the $TiO_2$ blocking layer. Our results indicate that the ECE of DSSCs can be enhanced by adding an appropriate amount of DBs to the $TiO_2$ blocking layers.

• Clean Technology
• /
• v.21 no.4
• /
• pp.235-240
• /
• 2015

In this study, vanadium dioxide was doped with titanium (0~0.5 at %) to improve thermochromic properties. The titanium doped vanadium dioxide (Ti-VO₂) particles were prepared via thermolysis process using vanadyl sulfate, ammonium bicarbonate and titianium chloride as precursors. The crystal structure, morphology, chemical bonding and thermochromic properties were investigated by using XRD, FE-SEM, XPS, DSC and UV-Vis-NIR spectroscopy. It was found that titanium was successfully doped into the crystal lattice of VO₂ and the obtained Ti-VO₂ particles have monoclinic structure. With increasing Ti concentration, the particle size and phase transition temperature of Ti-VO₂ particles decreased and NIR switching efficiency increased.

• Korean Journal of Metals and Materials
• /
• v.46 no.2
• /
• pp.88-96
• /
• 2008

Thermal evaporated 10 nm-$Ni_{50}Co_{50}$/(70 nm-poly)Si films were deposited to examine the energy saving properties of silicides formed by rapid thermal annealing at temperature ranging from 500 to $1,100^{\circ}C$ for 40 seconds. Thermal evaporated 10 nm-Ni/(70 nm-poly)Si films were also deposited as a reference using the same method for depositing the 10 nm-$Ni_{50}Co_{50}$/(70 nm-poly)Si films. A four-point probe was used to examine the sheet resistance. Transmission electron microscopy (TEM) and X-ray diffraction XRD were used to determine cross sectional microstructure and phase changes, respectively. UV-VIS-NIR and FT-IR (Fourier transform infrared spectroscopy) were used to examine the near-infrared (NIR) and middle-infrared (MIR) absorbance. TEM analysis confirmed that the uniform nickel-cobalt composite silicide layers approximately 21 to 55 nm in thickness had formed on the single and polycrystalline silicon substrates as well as on the 25 to 100 nm thick nickel silicide layers. In particular, nickel-cobalt composite silicides showed a low sheet resistance, even after rapid annealing at $1,100^{\circ}C$. Nickel-cobalt composite silicide and nickel silicide films on the single silicon substrates showed similar absorbance in the near-IR region, while those on the polycrystalline silicon substrates showed excellent absorbance until the 1,750 nm region. Silicides on polycrystalline substrates showed high absorbance in the middle IR region. Nickel-cobalt composite silicides on the poly-Si substrates annealed at $1,000^{\circ}C$ superior IR absorption on both NIR and MIR region. These results suggest that the newly proposed $Ni_{50}Co_{50}$ composite silicides may be suitable for applications of IR absorption coatings.

• Food Engineering Progress
• /
• v.13 no.4
• /
• pp.297-301
• /
• 2009

This study was performed to develop a prediction model of sugar content for strawberry. Near-infrared (NIR) spectroscopy has been prevailed for on-line and portable applications for non-invasive quality assessment of intact fruit. This work presents effects of illumination method and coating of reflection surface of light source on prediction result of sugar content. Effect of preprocessing methods was also examined. A low-cost commercially available VIS/NIR spectrometer was used for estimation of total soluble solids content (Brix). To predict sugar contents of strawberry, the best results were obtained with the spectrum data measured under intensive illuminations at three locations induced from the light source with fiber optic bundles. Gold coating of reflection surface of light source lamp gave favorable effect to prediction result. The best results in validation of PLSR model were $r_{SEP}$ = 0.891 and SEP = 0.443 Brix under OSC preprocessing and those of PCR were $r_{SEP}$ = 0.845, SEP $r_{SEP}$= 0.520 Brix, under no preprocessing.