Cu 기판위에 성장한 MgO, MgAl₂O₄와 MgAl₂O₄/MgO 박막의 집속이온빔을 이용한 스퍼터링수율 측정과 이차전자방출계수 측정

정강원(K. W. Jung),이혜정(H. J. Lee),정원희(W. H. Jung),오현주(H. J. Oh),박철우(C. W. Park),최은하(E. H. Choi),서윤호(Y. H. Seo),강승언(S. O. Kang) 한국진공학회(ASCT) 2006 Applied Science and Convergence Technology Vol.15 No.4

MgAl₂O₄ 막은 MgO 보호막 보다 단단하며 수분 흡착 오염문제에 상당히 강한 특성을 가진다. 본 연구에서 AC-PDP의 유전체보호막으로 사용되는 MgO 보호막의 특성을 개선하기 위해 MgAl₂O₄/MgO 이중층 보호막을 제작하여 특성을 조사하였다. 전자빔 증착기를 사용하여 Cu 기판에 MgO와 MgAl₂O₄을 각각 1000 Å 두께로 증착, MgAl₂O₄/MgO을 200/800 Å 두께로 적층 증착 후, 이온빔에 의한 충전현상을 제거하기 위해 Al을 1000 Å 두께로 증착하였다. 집속 이온빔(focused ion beam ; FIB)장치를 이용하여 10 ㎸에서 14 ㎸까지 이온빔 에너지에 따라 MgO는 0.364 ~ 0.449 값의 스퍼터링 수율에서 MgAl₂O₄/MgO을 적층함으로 24 ~ 30 % 낮아진 0.244 ~ 0.357 값의 스퍼터링 수율이 측정되었으며, MgAl₂O₄는 가장 낮은 0.088 ~ 0.109 값의 스퍼터링 수율이 측정되었다. g-집속이온빔(g-FIB)장치를 이용하여 Ne? 이온 에너지를 50 V에서 200 V까지 변화 시켜 MgAl₂O₄/MgO와 MgO는 0.09 ~ 0.12의 비슷한 이차전자방출 계수를 측정 하였다. AC-PDP셀의 72시간 열화실험 후 SEM 및 AFM으로 열화된 보호막의 표면을 관찰하여 기존의 단일 MgO 보호막과 MgAl₂O₄/MgO의 적층보호막의 열화특성을 살펴보았다. It is known that MgAl₂O₄ has higher resistance to moisture than MgO, in humid ambient MgO is chemically unstable. It reacts very easily with moisture in the air. In this study, the characteristic of MgAl₂O₄ and MgAl₂O₄/MgO layers as dielectric protection layers for AC-PDP (Plasma Display Panel) have been investigated and analysed in comparison for conventional MgO layers. MgO and MgAl₂O₄ films both with a thickness of 1000 Å and MgAl₂O₄/MgO film with a thickness of 200/800 Å were grown on the Cu substrates using the electron beam evaporation. 1000 Å thick aluminium layers were deposited on the protective layes in order to avoid the charging effect of Ga? ion beam while the focused ion beam(FIB)is being used. We obtained sputtering yieds for the MgO, MgAl₂O₄ and MgAl₂O₄/MgO films using the FIB system. MgAl₂O₄/MgO protective layers have been found th show 24 ~ 30% lower sputtering yield values from 0.244 up to 0.357 than MgO layers with the values from 0.364 up to 0.449 for irradiated Ga? ion beam with energies ranged from 10 ㎸ to 14 ㎸. And MgAl₂O₄ layers have been found to show lowest sputtering yield values from 0.88 up to 0.109. Secondary electron emission coefficient(g) using the γ-FIB. MgAl₂O₄/MgO and MgO have been found to have similar g values from 0.09 up to 0.12 for indicated Ne+ ion with energies ranged from 50 V to 200 V. Observed images for the surfaces of MgO and MgAl₂O₄/MgO protective layers, after discharge degradation process for 72 hours by SEM and AFM. It is found that MgAl₂O₄/MgO protective layer has superior hardness and degradation resistance properties to MgO protective layer.

Effect of Network Polymerization on the Pressure-Induced Structural Changes in Sodium Aluminosilicate Glasses and Melts: ²⁷Al and ¹⁷O Solid-State NMR Study

Lee, Sung Keun,Yi, Yoo Soo,Cody, George D.,Mibe, Kenji,Fei, Yingwei,Mysen, Bjorn O. American Chemical Society 2012 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.116 No.3

<P>Probing the pressure-induced structural changes and the extent of disorder in aluminosilicate glasses and melts at high pressure remains a challenge in modern physical and chemical sciences. With an aim of establishing a systematic relationship between pressure, composition, and glass structures, we report <SUP>27</SUP>Al and <SUP>17</SUP>O 3QMAS NMR spectra for sodium aluminosilicate glasses [Na<SUB>2</SUB>O:Al<SUB>2</SUB>O<SUB>3</SUB>:SiO<SUB>2</SUB> = 1.5:0.5:2<I>n</I> with <I>n</I> = 1 (NAS150520, <I>X</I><SUB>SiO2</SUB> = 0.5), 2 (NAS150540, <I>X</I><SUB>SiO2</SUB> = 0.67), and 3 (NAS150560, <I>X</I><SUB>SiO2</SUB> = 0.75)], quenched from melts at pressures up to 8 GPa. We also explore the stability of the <SUP>[4]</SUP>Al–O–<SUP>[4]</SUP>Al cluster in the highly depolymerized, NAS150520, glass at high pressure. For given glass composition, the <SUP>[5,6]</SUP>Al peak intensity increases with increasing pressure. The population of <SUP>[5,6]</SUP>Al increases linearly with <I>X</I><SUB>SiO2</SUB> from NAS150520 (<I>X</I><SUB>SiO2</SUB> = 0.5) to NAS150560 glass (<I>X</I><SUB>SiO2</SUB> = 0.75) at both 6 and 8 GPa. The <SUP>[5,6]</SUP>Al/<I>X</I><SUB>SiO2</SUB> ratio also tends to increase with pressure, indicating a possible relationship between <SUP>[5,6]</SUP>Al fraction and <I>X</I><SUB>SiO2</SUB> that depends on pressure. The effect of pressure on the network connectivity in the sodium aluminosilicate glasses is manifested in the increase in <SUP>[4]</SUP>Si–O–<SUP>[5,6]</SUP>Al peak intensity and the decrease in the nonbridging oxygen (NBO) fraction with increasing pressure. The fraction of <SUP>[4]</SUP>Si–O–<SUP>[5,6]</SUP>Al in NAS150520 is smaller than in NAS150560. Taking into consideration the pressure-induced Al coordination transformation in the fully polymerized glass (albite, Na<SUB>2</SUB>O:Al<SUB>2</SUB>O<SUB>3</SUB>:SiO<SUB>2</SUB>= 1:1:6, NBO/T = 0), the fraction of <SUP>[5,6]</SUP>Al at a given pressure varies <I>nonlinearly</I> with variations of NBO/T. <SUP>[5,6]</SUP>Al fraction at 8 GPa increases with decreasing degree of melt polymerization from ∼8% for fully polymerized albite melt (NBO/T = 0) to ∼37% for partially depolymerized melt (NAS150560, at NBO/T = 0.29). Then it gradually decreases to ∼15% for NAS150520 with further increase in NBO/T of 0.67. This observed trend in the densification behavior at a given pressure indicates competing densification mechanisms involving steric hindrance vs changes of NBO fraction in the silicate melts. The NMR results also suggest that both NBO and BO, particularly <SUP>[4]</SUP>Si–O–<SUP>[4]</SUP>Si, interact with Na<SUP>+</SUP>, and thus the Na<SUP>+</SUP> distribution is likely to be homogeneous around both NBO and BO at high pressure without spatial segregation of silica-rich and alkali-rich domains for the glass compositions studied here. The presence of the <SUP>[4]</SUP>Al–O–<SUP>[4]</SUP>Al cluster is distinct in the NMR spectrum for NAS150520 glass at both 6 and 8 GPa. A new scheme of pressure-induced structural transitions in silicate melts involving <SUP>[4]</SUP>Al–O–<SUP>[4]</SUP>Al includes the formation of <SUP>[4]</SUP>Al–O–<SUP>[5]</SUP>Al.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2012/jpccck.2012.116.issue-3/jp206765s/production/images/medium/jp-2011-06765s_0008.gif'></P>

Pb(Zr_0.56 Ti_0.44)O₃+ x[wt%]Cr₂O₃세라믹스의 길이진동에 대한 온도안정성

김동오,한성훈,이개명 濟州大學校 情報通信硏究所 1999 情報通信硏究所論文集 Vol.2 No.-

Recently mobile communication fields need piezoelectric ceramic resonators and filters as possible as small. The length-extensional vibration mode of a rectangular piezoelectric ceramic plate has the advantage of the small size. but the mode has not been studied sufficiently because it was not used extensively until now. In this paper. PZT + x[wt%] Cr₂O₃ ceramics with rhombohedral phase were fabricated. And temperature stability for the mode of the ceramic specimen was investigated. Contrary to our expectations. addition of the stabilizer. Cr₂O₃did not promote the temperature stability for the mode in the PZT ceramic specimen with rhombohedral phase.

A study of nerve agent model organophosphonate binding with manganese-A₂B-corrole and -A₂B₂-porphyrin systems

Kim, K.,Kim, I.,Maiti, N.,Kwon, S.J.,Bucella, D.,Egorova, O.A.,Lee, Y.S.,Kwak, J.,Churchill, D.G. Pergamon Press 2009 Polyhedron Vol.28 No.12

Herein the synthesis and binding studies of novel trans-A<SUB>2</SUB>B-corrole and trans-A<SUB>2</SUB>B<SUB>2</SUB>-porphyrin derivatives are presented in comparing manganese(III)-organophosphonate (OP) binding (e.g., M<SUP>n+</SUP>←O?PR(OR)<SUB>2</SUB>) capabilities. H<SUB>3</SUB>(PFP-VC) [PFP-VC=5,15-di(pentafluorophenyl)-10-(3-vinylphenyl)corrolate] was synthesized by way of literature procedures and was characterized by a variety of 2-D NMR spectroscopic techniques and single-crystal X-ray diffraction. These compounds represent the first example of 3-vinyl-phenyl-containing meso-substituted corroles or porphyrins. Mn(PFP-VC) (3) was treated separately with (CH<SUB>3</SUB>CH<SUB>2</SUB>O)<SUB>2</SUB>P?O(C<SUB>3</SUB>H<SUB>6</SUB>NMe<SUB>2</SUB>), (C<SUB>4</SUB>H<SUB>9</SUB>O)<SUB>2</SUB>P?O(Me), (C<SUB>2</SUB>H<SUB>5</SUB>O)<SUB>2</SUB>P?O(CH<SUB>2</SUB>COCH<SUB>3</SUB>), (CH<SUB>3</SUB>CH<SUB>2</SUB>O)<SUB>2</SUB>P?O(Me), to give 1:1 adducts, as determined by UV-Vis spectroscopy (Job Plot), giving a red shift; Ph<SUB>3</SUB>P?O, was also found to bind, but very weakly. The trans-A<SUB>2</SUB>B<SUB>2</SUB>-porphyrin analogue Mn(PFP-VP) (4) was also prepared by way of a literature procedure; related binding studies gave 1:1 organophosphonate-Mn(PFP-VP) adducts (Job Plot). A clean blue shift occurred for the Mn-porphyrins at higher organophosphonate loadings (K<SUB>a</SUB> values: 6.7 (0.9)-11.9 (0.4)M<SUP>-1</SUP>). DFT geometry optimizations of O?P(OMe)<SUB>2</SUB>Me binding and formal Mn-O or P-O cleavage products in the unsubstituted neutral Mn-corrolato and -porphyrinato systems with a range of metal-based spin states revealed greatest stability in formal phosphoryl oxygen binding (energies: 11-13kcal/mol) for the Mn-corrole (singlet); the Mn-porphyrin (sextet) was also quite stable.

Influence of Annealing Temperature on Magnetoelectric Properties of CoFe2O4/Pt/Pb(Zr0.3Ti0.7)O3 Thin Films

Eum, Y.J.,Hwang, S.-O.,Ryu, J.,Kim, J.-W.,Koo, C.Y.,Lee, J.-Y.,Lee, H.Y. Taylor Francis 2014 Ferroelectrics Vol.465 No.-

<P>CoFe2O4/Pt/Pb(Zr0.3Ti0.7)O-3 thin films were grown on Pt/Ti/SiO2/Si substrate in order to investigate the magnetoelectric properties of ferromagnetic/ferroelectric multilayer thin films. Thin Pt layer was introduced to prevent inter-diffusion between CoFe2O4 and Pb(Zr0.3Ti0.7)O-3 (PZT) layers. PZT thin film was grown directly on top of Pt substrate by utilizing sol-gel spin coating technique. In order to investigate the possible annealing effect on film microstructure and magnetoelectric properties, multilayer thin film stack was heat-treated at different temperatures ranging from 550 degrees C to 650 degrees C. The structural properties of the films were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Ferroelectric and ferromagnetic behaviors were analyzed by measuring polarization and magnetization - electric and magnetic field hysteresis. Magnetoelectric coefficients were calculated by measuring magnetoelectric voltages using magnetoelectric measurement system. Both the magnetoelectric properties and the coupling effect of CoFe2O4/Pt/PZT films on ferromagnetic and magnetoelectric properties are discussed as a function of heat-treatment temperature.</P>

피스톤의 편심이 O-ring의 변형특성에 미치는 영향

이준혁(J. H. Lee),이준오(J. O. Lee),박태조(T. J. Park) 유공압건설기계학회 2012 유공압건설기계학회 학술대회논문집 Vol.2012 No.6

O-ring seal is widely used in various mechanical devices to prevent mainly leakage of working fluid and incursion of foreign particle. When O-ring is used as a piston seal, the sealing performances are determined by various design parameters such as initial interference, fluid pressure and the clearance gap between piston and cylinder. In this paper, a nonlinear problem solver, MARC, is adopted to analyze the effect of piston eccentricity and fluid pressure on the deformation characteristics of O-ring seal. The results show that the eccentricity of piston can reduce highly the ability of the seal, and then cause easily leakage of fluid.

Magnetoelectric Coupling of CuFe2O4/Pt/Pb(Zr0.52Ti0.48)O3 Multilayer Thin Films

Hwang, S.-O.,Eum, Y.J.,Kim, J.-W.,Ryu, J.,Koo, C.Y.,Lee, J.-Y.,Lee, H.Y. Taylor Francis 2014 Ferroelectrics Vol.465 No.-

<P>CuFe2O4/Pt/Pb(Zr0.52Ti0.48)O-3 (PZT) multilayer thin films were grown on (111)-oriented Pt/TiO2/SiO2/Si < 100 > substrate. PZT layer was fabricated by the sol-gel method. Afterwards, Pt layer was deposited by ion beam sputtering method. Finally, CuFe2O4 layer were deposited using pulsed laser deposition method (PLD). The film structure is tri-layered type, where the bottom PZT layer covered the whole substrate, while Pt and CuFe2O4 layers were deposited through circular shadow masks to measure ferroelectric and magnetoelectric properties. Film microstructure was observed using XRD and FE-SEM. Magnetoelectric coefficients were calculated by measured magnetoelectric voltages using magnetoelectric measurement system.</P>

Effects of Pressure and Electrode Length on the Abatement of N2O and CF4 in a Low-Pressure Plasma Reactor

Hur, M.,Lee, J. O.,Lee, J. Y.,Kang, W. S.,Song, Y. H. Springer Science + Business Media 2016 Plasma chemistry and plasma processing Vol.36 No.6

<P>The emission of greenhouse gases, such as N2O and fluorinated gases, has been increasingly regulated in the semiconductor industry. Pressure effects on the abatement of N2O and CF4 were investigated in a low-pressure plasma reactor by using Fourier transform infrared (FTIR) spectroscopy. The destruction and removal efficiency (DRE) of N2O and CF4 was significantly lowered below 0.2 Torr. When the pressure was increased, the DRE of CF4 with H2O as the reactant gas increased continuously, but that with O-2 or without any reactant gas first increased and then decreased. A larger electrode length yielded a higher DRE of N2O and CF4, especially at lower pressures. To understand this phenomenon, the electrical waveforms for the discharge in N2O were analyzed in conjunction with its optical emission profiles, and the rotational temperatures for different electrode lengths were compared using the N-2 (+) ion band (lambda = 391.4 nm). They provided insights into the mechanism involved in terms of plasma property and gas residence time.</P>

Dimethyl Phthalate의 오존산화 반응에 관한 연구

이철규(Cheal Gyu Lee),송준오(Jun O Song) 大韓環境工學會 2013 대한환경공학회지 Vol.35 No.10

실험실적 규모의 순환형 회분식 반응기에서 Dimethyl phthalate (DMP)성분을 효율적으로 제거하기 위하여 Al₂O₃촉매의 주입 그리고 반응온도의 조건을 달리하여 오존산화 반응을 수행하였다. 산화 반응에서 오존의 유량은 1.0 L min-1, 오존 농도를 300 ± 10 mg L-1로 일정하게 유지 하였으며, 산화 반응이 진행되는 60분 동안 10분 간격으로 pH, CODCr와 TOC를 측정하여 이를 비교 분석하였다. O₃/Al₂O₃에서는 O₃ 단독 공정에 비해 CODCr 및 TOC 측정값에 기초한 제거효율은 증가하였으며, 20℃에서 CODCr 및 TOC의 반응속도상수는 3.65 × 10-4 sec-1, 2.52 × 10-4 sec-1, 활성화 에너지는 0.75 kcal·mol-1, 0.70 kcal·mol-1로 각각 나타났다. Ozonation was performed under various experimental conditions that Al₂O₃ catalysts dosage and temperature for removal of DMP in laboratory scale batch reactor. Flow rate of ozone 1.0 L min-1 and ozone concentration of 300 ± 10 mg L-1 were maintained constantly, and the pH, CODCr and TOC was measured in 10 min intervals during the 60 min at oxidation processes. As a result, the presence of the Al₂O₃ than only ozonation increased the removal efficiency of both CODCr and TOC in solution. The pseudo first-order rate constants for the elimination of CODCr and TOC were 3.65 × 10-4 sec-1, 2.52 × 10-4 sec-1, and activation energy was 0.75 kcal·mol-1 and 0.70 kcal·mol-1 at 20℃, respectively.

고온가스정제공정의 후류 연료가스를 이용한 SO₂의 직접환원에 관한 연구

박노국,김봉석,이종대,전진혁,류시옥,이태진 한국공업화학회 2003 응용화학 Vol.7 No.2

The catalytic reactivity for the direct sulfur recovery from the produced SO₂in the regeneration process to element sulfur with the slip-stream fuel gas of hot gas desulfurization process as reductant was studied. The the catalyst for directly sulfur recovery process was used Ce_(0.8)Zr_(0.2)O₂, and the SO₂conversion and the element sulfur yield were investigated with the change of a reaction conditions, such as the amount of H₂O(2-10vol%), the reaction temperatures(400-600℃) and the mole ratio of reactants([reductant]/[SO₂]〓 1.0-3.0). The SO₂conversion and the element sulfur yield decreased by increasing the amount of H₂O in the slip-stream fuel gas using as reductant and increased by increasing the reaction temperature and the mole ratio of reactants. From TPR experiment result, reason that the SO₂conversion and the element sulfur yield becomes low by H₂O was confirmed because that the water-gas shift reaction(CO + H₂O → CO₂+ H₂). Specially, the element sulfur yield was fallen due to that created hydrogen to the water-gas shift reaction is converted to H₂S reacting with element sulfur.