• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.215-215
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• 2012

급속한 산업의 발달은 심각한 환경오염 및 에너지 문제를 가져왔다. 이를 해결하기 위한 방안으로 수소에너지에 대한 관심이 증가하고 있으며, 수소에너지를 생산하는 방법 중 하나로 태양에너지를 원천으로 하는 광촉매(photocatalyst)에 대한 연구가 점차적으로 증가하고 있는 추세이다. 현재 광촉매로 가장 많이 사용되는 $TiO_2$의 경우, 뛰어난 광활성과 저렴한 가격, 광 안정성, 화학적 안정성을 가짐에도 불구하고, 3.2 eV라는 넓은 band gap을 가지기 때문에 385 nm 이상의 긴 파장을 갖는 가시광선은 흡수할 수 없다. 또한, 광촉매 반응과정 중 recombination으로 인한 효율의 손실이 크기 때문에 이러한 문제들을 해결하기 위해 많은 연구가 진행되어 왔다. 본 연구에서는 ICP-assisted DC magnetron sputtering 방법을 이용하여 높은 결정성을 갖는 $TiO_2$ 박막을 제조하였다. 제작된 $TiO_2$ 박막은 높은 광촉매 특성을 나타냈으며, 또한 $TiO_2$의 anatase phase와 rutile phase의 bilayer structure를 통하여 recombination을 감소시킴으로써 높은 효율을 갖는 광촉매를 제작하였다. 박막의 chemical state와 crystallinity를 확인하기 위하여 X-ray photoelectron spectroscopy와 X-ray diffractometer를 이용하여 분석을 수행하였으며, 물 분해 장치(water splitting device)를 제작하여 수소와 산소 생성시 흐르는 전류를 측정하여 광촉매 특성을 평가하였다.

• Journal of Magnetics
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• 제21권1호
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• pp.46-50
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• 2016

$Fe_2O_3/TiO_2$ nanocomposite were successfully synthesized by co-precipitation method using $Fe(NO_3)_3{\cdot}9H_2O$ and $Ti(SO_4)_2$ as raw materials. Structural and textural features of the mixed oxide samples were characterized by X-ray diffractometer, field emission scanning electron microscopy and energy-dispersive X-ray. The effects of initial concentration of oxytetracycline (OTC), different competitive ions and organics on the photocatalytic degradation rate of OTC by the $Fe_2O_3/TiO_2$ nanocomposite were analyzed under UV and visible light irradiation. The results indicate that the optimized initial concentration of OTC was 50 mg/L to achieve the best photocatalytic efficiency. $Cu^{2+}$, $NH_4{^+}$, $C_3H_8O$ and EDTA in the aqueous suspension were found to suppress the degradation rate of OTC, whereas the effect of $NO_3{^-}$ and $H_2C_2O_4$ can be ignored.

• 전기학회논문지
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• 제59권7호
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• pp.1255-1258
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• 2010

In this paper, the $CoSi_2$ thin films with thicknesses of about $5{\mu}m$ were deposited on n-type silicon (111) substrates by RF magnetron sputtering method using a $CoSi_2$ target (99.99%). The flow rate of argon of 50 sccm, substrate temperature of $100^{\circ}C$, RF power of 60 watts, deposition time of 30 minutes, and the vacuum of $1\times10^{-6}$ Torr. The annealing treatments of the $CoSi_2$ thin film were performed from 500, 700 and $900^{\circ}C$ for 1h in air ambient by an electric furnace. In order to investigate the $CoSi_2$ thin film X-ray diffraction patterns were measured using the X-ray diffractometer (XRD). The structure of the thin films were investigated by using scanning the electron microscope (SEM) were used for review. The surface morphology of the thin films was measured with a atomic force microscopy (AFM). Temperature dependence of sheet resistivity and property of Hall effect was measured in the $CoSi_2$ thin film.

• 펄프종이기술
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• 제44권4호
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• pp.43-50
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• 2012

The crystallinity index is an important characteristic of cellulose. The crystallinity value is different depending on the adopted instrument. In this study, we determined a crystallinity index of cotton and wood celluloses using wide-angle X-ray scattering (WAXS), powder X-ray diffractometer (PXRD), and cross polarization/magic angle spinning solid-state $^{13}C$ nuclear magnetic resonance spectroscopy (CP/MAS solid-state $^{13}C$ NMR). The specimen was prepared in forms of powder, sheet and pallet. With the comparison of the obtained crystallinity indices of the cellulose, the effects of the analysis instrument, the sample preparation and analysis method were investigated. Among three instruments, the crystallinity indices by PXRD and NMR had a good relationship and reproducibility, and WAXS gave the crystallinity index with poor reproducibility. In the case of analysis methods of crystallinity indices, the Segal method showed higher value than that of the Ruland-Vonk method. We expect that this study would be applicable to evaluate the crystallinity index of various cellulose materials with accuracy and reproducibility.

• 대한금속재료학회지
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• 제46권6호
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• pp.370-376
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• 2008

The formation of anodic oxide film of titanium (Ti) was studied at a variety of electrolyte concentrations and current density to clarify their effects on morphology, microstructure and composition of Ti oxide layer. For the analysis of the Ti oxide films, a scanning electron microscopy (SEM), X-ray diffractometer (XRD), and X-ray photoelectron spectroscopy (XPS) were used. The results showed that the concentration of phosphoric acid played a crucial role in the crystalline structure of the Ti oxide layer while the current density gave a critical effect on the thickness and diameter of its pore. In particular, the crystalline anatase phase with a thickness larger than $2{\mu}m$, which is quite desirable for a dental implant application, could be readily prepared at the phosphoric acid concentration of 0.5 M and current density higher than $2.0A/dm^2$.

• Bulletin of the Korean Chemical Society
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• 제15권12호
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• pp.1108-1112
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• 1994

25-Acetoxy-26,27,28-trimethoxycalix[4]arene was synthesized by the treatment of calix[4]arene trimethyl ether with acetyl chloride in the presence of NaH. The solution conformation was inferred as a partial cone conformation based on the $^1H$-and $^{13}C$ NMR spectra. The crystal structure has been determined by X-ray diffraction method. The crystals are monoclinic, space group $P2_1$/n, a=8.186 (1), b=17.137 (2), c=19.878 (3) ${\AA}$, ${\beta}$=95.67 (1)$^{\circ}$, Z=4, V=2774.90 ${\AA}^3$, $D_c$= 1.22 g $cm^{-3}$, $D_m$=1.23 g $cm^{-3}$. The intensity data were collected on an Enraf-Noninus CAD-4 Diffractometer with a graphite monochromated $Cu-K{\alpha}$ radiation. The structure was solved by direct method and refined by full-matrix least-squares methods to a final R value of 0.054 for 3675 observed reflections. The molecule possesses a partial cone conformation with one flattened phenyl unit, in which one anisol ring, distal to the ester ring, is inverted. The acetoxyphenyl ring is flattened.

• Journal of the Korean Physical Society
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• 제73권9호
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• pp.1351-1355
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• 2018

The photocurrent characteristics of zinc-oxide (ZnO) thin-film transistors (TFTs) prepared using radio-frequency sputtering and spin-coating methods were investigated. Various characterization methods were used to compare the physical and the chemical properties of the sputtered and the spin-coated ZnO films. X-ray photoelectron spectroscopy was used to investigate the chemical composition and state of the ZnO films. The transmittance and the optical band gap were measured by using UV-vis spectrometry. The crystal structures of the prepared ZnO films were examined by using an X-ray diffractometer, and the surfaces of the films were investigated by using scanning electron microscopy. ZnO TFTs were prepared using both sputter and solution processes, both of which showed photocurrent characteristics when illuminated by light. The sputtered ZnO TFTs had a photoresponsivity of 3.08 mA/W under illumination with 405-nm light while the solution-processed ZnO TFTs had a photoresponsivity of 5.56 mA/W. This study provides useful information for the development of optoelectronics based on ZnO.

• 한국군사과학기술학회지
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• 제4권1호
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• pp.198-206
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• 2001

X-선 /회절법으로 3-nitro-1,2,4-triazol-5-one(NTO)와 Yb의 금속착물인 $[Yb(NTO)_3(H_2O)_4].5H_2O$의 결정구조를 조사하였다. 결정계는 단사정계, C2/c, a=36.925(2)${\AA},$ b=6.6770(4)${\AA},$ c=25.6376(15)${\AA},$ ${\beta}=130.978(1)^{\circ},$ V=4772.0(5)${\AA}^3,$ Z=8, $D_c=1.952 \;Mg/m^3$ 이다. 회절반점들의 세기는 CCD 면적 검출장치를 장착한 Bruker SMART diffractometer로 얻었으며 Mo $K\alpha$ X-선을 사용하였다. 분자구조는 직접법으로 풀었으며 최소자승법으로 정밀화하였다. 최종신뢰도 R값은 4727개의 독립회절반점으로 335개의 파라메타에 대하여 0.0424 이었다. 4개의 배위 물분자와 NTO 음이온의 3개 카르보닐기는 pentagonal bipyramid를 이루며 $Yb^{3+}$ 양이온과 연결되어 있고 또한 5개의 물분자가 결정수의 형태로 분자구조에 포함되어 있다.

• 한국결정학회지
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• 제15권2호
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• pp.93-98
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• 2004

X-선 회절법을 이용하여 C_{28}H_{41}N_4O_4Br\;{\cdo}t\;2H_2O$의 분자 및 결정구조를 해석하였다. 이 결정의 결정계는 Triclinic이고 공간군은 Pl이며, 단위포 상수 a=9.000(1) $\AA$, b=9.312(3) $\AA$, c=9.344(2) $\AA$, $\alpha=89.37(20)^{\circ},\;\beta=68.81(3)^{\circ},\;\gamma=84.70(4)^{\circ},\;V=726.7(8){\AA},\;T=298K,\;Z=1,\;D_c=1.402Mgm^{-3}$이다. 회절반점들의 세기는 Enraf-Nonius CAD4 Diffractometer로 얻었으며 사용한 X-선은 graphite로 단색화한 $MoK{\alpha}$선$(\lambda=0.71073\;{\AA}$을 사용하였다. 분자구조는 Direct method로 풀었으며, $F_o>4{\sigma}(F_0)$인 2521개의 독립 회절 데이터에 대하여 최소 자승법으로 370개의 변수를 정밀화하여 최종 신뢰도 값 $R=5.95\%$를 얻었다.

• 한국결정학회지
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• 제10권1호
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• pp.1-8
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• 1999

Two conformational isomers of p-tert-butylcalix[4]arene hexanoate were prepared from the reaction of-p-tert-butylcalix[4]arene and hexanoly chloride in the presence of AlCl3 in CH2Cl2 and their structures were determined by NMR spectra and X-ray diffraction as a cone and a 1,3-alternate conformer, respectively. The crystal of cone conformer (C68H96O8·(CH3)2CO) is triclinic, P, a=15.066(1) , b=16.063(1) , c=16.365(1) , α=79.75(2)o, β=109.95(2)o, γ=80.32(0)o, V=3602.7(4) 3, Z=2. The intensity data were collected on Simens SMART diffractometer/CCD area detector. The structure was solved by direct method and refined by least-squares calculations to a final R value of 0.144 for 4638 observed reflections. The molecular conformation is distorted symmetric cone with the flattening A and D phenyl rings. The crystal of 1,3-alternate conformer (C68H96O8·2CHCl3) is orthorhombic, Pca21, a=34.586(5) , b=10.207(3) , c=20.394(4) , V=7199(3) 3, Z=4. The intensity data were collected on an Enraf-Noninus CAD-4 Diffractometer with a graphite monochromated Mo-K radiation. The structure was solved by direct method and refined by least-squares calculations to a final R value of 0.152 for 2241 observed reflections. The molecule has a pseudo mirror symmetric 1,3-alternate conformation.