• 폴리머
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• 제30권5호
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• pp.412-416
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• 2006

$FeCl_3$와 $Na_2SO_3,\;NH_4OH$에 의해 제조된 나노 자철광은 강자성체로 화학 흡착에 의해 형성된 표면의 수산기에 의해 표면전하가 변하는 특성이 있다. 본 연구는 이런 나노 자철광을 함유한 poly(acrylic acid) (PAAc) 수화젤의 물성에 대하여 연구하였다. 나노 자철광의 특성은 XRD, AFM, FTIR로 측정하였다. 나노 자철광 표면의 제타전위는 pH 변화에 의해 큰 영향을 받았으며, pH 4 이하에서는 높은(+)전위를 나타내었으며, 등전점은 pH 7에서 확인되었다. pH 4 이하에서 나노 자철광 콜로이드를 PAAc 수화젤에 함유시키면, 강력한 수소결합이 형성되어 젤의 인장강도는 증가하고, 신율 및 팽윤비는 감소하여 기계적인 물성이 증가하였다. 나노 자철광의 함량에 비례하여 나노 자철광을 함유한 PAAc 수화젤의 자기이력은 증가하였다.

• 한국진공학회지
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• 제9권1호
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• pp.36-41
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• 2000

$SnO-2$ thin films for thin film secondary battery anode were deposited n glass substrate with stain-less steel collector and charge/discharge experiments were conducted to investigate feasibility of $SnO-2$ thin film as a new anode material. The as-deposited films were pure $SnO-2$ phase which is not related to deposition condition. The grain size on the surface of as-deposited films increased with increase of oxygen partial pressure. However, the grain size did not show any change above oxygen partial pressure of 80:20. The surface roughness of the as-deposited films increased after decreasing because of resputtering effect of oxygen negative ion in plasma. All films showed typical $SnO-2$ anode characteristics which has a side effect at the first cycle, which is not related to the deposition condition. The charge/discharge experiments of 200cycles indicated that capacity of $SnO-2$ films depended on oxygen contents and surface roughness. The cycle characteristics was determined by initial charge/discharge reaction. The $SnO-2$ film with low initial capacity showed more stable cycle characteristics than film with high initial capacity.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.175.1-175.1
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• 2014

Despite growing interest in Ge as a possible alternative to Si, reliable data on Ge surface has been relatively scarce. Using low temperature scanning tunneling microscopy (STM), we investigate band-bending effects of localized charge traps at Ge(001) surface at 78 K. For this investigation, we prepared nearly defect-free Ge(001) surface by keeping the background pressure to < $1{\times}10^{-10}$ mbar during outgassing. Ge(001) surfaces this obtained exhibit a flat-band condition, and deposition of charge traps induce a distinct, sharp boundary between pinned and depinned surface area in the constant current mode STM images. We will show the tip-surface interaction plays an essential role in producing the boundary, and discuss about the conditions that enable the pinning effect.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.360-360
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• 2010

Very initial stage of oxidation process of Si (001) surface was investigated using large scale molecular dynamics simulation. Reactive force field potential was used for the simulation owing to its ability to handle charge variation associated with the oxidation reaction. To know the detail mechanism of both adsorption and desorption of water molecule (for simulating wet oxidation), oxygen molecule (for dry oxidation) and their atom constituents, interaction of one molecule with Si surface was carefully observed. The simulation is then continued with many water and oxygen molecules to understand the kinetics of oxide growth. The results show that possibilities of desorption and adsorption depend strongly on initial atomic configuration as well as temperature. We observed a tendency that H atoms come relatively into deeper surface or otherwise quickly desorbed away from the silicon surface. On the other hand, most oxygen atoms are bonded with first layer of silicon surface. We also noticed that charge transfer is only occur in nearest neighbor regime which has been pointed out by DFT calculation. Atomic structure of the interface between the oxide and Si substrate was characterized in atomic scale.

• Applied Microscopy
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• 제45권4호
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• pp.214-217
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• 2015

This study introduces metal coating as an effective sample preparation method to remove charge-up caused by the shadow effect during field emission scanning electron microscope (FE-SEM) analysis of dynamic structured samples. During a FE-SEM analysis, charge-up occurs when the primary electrons (input electrons) that scan the specimens are not equal to the output electrons (secondary electrons, backscattered electrons, auger electrons, etc.) generated from the specimens. To remove charge-up, a metal layer of Pt, Au or Pd is applied on the surface of the sample. However, in some cases, charge-up still occurs due to the shadow effect. This study developed a coating method that effectively removes charge-up. By creating a converted sample stage capable of simultaneous tilt and rotation, the shadow effect was successfully removed, and image data without charge-up were obtained.

• Korean Chemical Engineering Research
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• 제50권2호
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• pp.379-384
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• 2012

이산화티탄 표면에 흡착되는 금 입자의 분포 또는 그 반대 경우의 분포에 영향을 끼칠 수도 있는 정전기적 상호작용과 금 입자를 코팅한 Glutathione 층의 표면물성을 규명하였다. 이를 위하여, 원자힘현미경(AFM)으로 Glutathione 층표면과 이산화티탄표면 사이의 표면힘을 염 농도와 pH 값에 따라 측정하였다. 측정된 힘은 Derjaguin-Landau-Verwey-Overbeek(DLVO) 이론으로 해석되어 표면의 정전기적인 특성들이 정량적으로 산출되었다. 이 특성들이 염 농도와 pH에 대하여 나타내는 의존성을 질량보존의 법칙으로 기술하였다. pH 8과 11에서 실험으로 산출된 표면 특성의 염 농도 의존성은 이론적으로 예측했던 결과와 일치하는 것으로 관찰되었다. pH 8과 11에서 Glutathione 층의 표면이 이산화티탄 표면보다 높은 정전기적 특성을 갖는 것이 발견되었는데, 이는 Glutathione 층의 이온화-기능-그룹에 기인한 것으로 생각된다.

• 한국의류학회지
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• 제22권8호
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• pp.1132-1140
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• 1998

The adhesion and removal of $\alpha$-Fe2O3 particles on the from PET fabric in NPE solution with different ionic strength were discussed in terms of interaction of surface charge of particle and substrate. The adhesion of $\alpha$-Fe2O3 particles to PET fabric and its removal from PET fabric were carried out by using water bath shaker and Terg-O-Tometer under various solution conditions. The ζ potential of PET fiber and $\alpha$-Fe2O3 particles in the detergent solution were measured by steaming potential and microelectrophoresis methods, respectively. The adhesion and removal amount of $\alpha$-Fe2O3 particles on the from PET fabric increased with increasing time of adhesion and removal, and the rates of adhesion and removal were high at the initial stage of adhesion and removal, and then the rates decreased with passing time. The adhesion and removal amount of $\alpha$-Fe2O3 particles on and from PET fabric increased with increasing pH of solution regardless ionic strength. The tendencies and degree of adhesion and removal were very similar regardless interaction of surface charge of particle and fiber. Therefore, in the presence of a surfactant and electrolyte, the influence of interaction of surface charge of particle and substrate on the detergency of particulate soil was small.

• Korean Chemical Engineering Research
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• 제49권5호
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• pp.554-559
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• 2011

리튬금속을 음전극으로 사용할 때의 안전성과 전극 특성을 개선하기 위해, 리튬금속 표면에 각기 종류가 다른 3가지의 탄소분말을 리튬금속 표면에 물리적으로 코팅한 전극을 제조하고 이를 리튬 2차전지의 음전극으로 채택하여 충방전 특성을 조사하였다. 일차입자의 입경이 작고 비표면적이 큰 탄소분말로 코팅한 음전극을 채택하는 경우가 충진밀도가 높고 표면 거칠기가 낮으며, 충방전 특성도 우수하게 나타났다. 이러한 탄소분말 코팅 효과는 소형 셀일수록 더욱 유리하게 나타났다.

• Journal of the Korean Wood Science and Technology
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• 제22권1호
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• pp.85-90
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• 1994

The flow properties of binder latices for paper coating were investigated, together with dynamic viscoelastic properties of latex films and electron micrographs of latices, under various conditions. The amphoteric latex, binder pigment latex and anionic latex were used in this work. The amphoteric latex has both anionic and cationic functional group on its surface. The binder-pigment with a core-shell structure has dual functions : plastic pigment and binder. The low shear viscosity of binder latices and clay slurry were measured with Brookfield vis cometer. At low-shear rates. the viscosity decreased with increasing particle size of latex. On the amphoteric latex surface, the carboxyl groups are assumed to be fully dissociated over the region of pH 9~12, but the density of negative groups seems to be increased because of the gradual decrease in the degree of dissociation of amino groups. Since the apparent particle size of latex increases with surface charge, the electroviscous effect can be observed. On the anionic latex surface, the charge density is assumed to be nearly constant above pH 8. However, below pH 8 the coagulation of particles could be observed probably because of the decrease in the charge density.

• Journal of Electrochemical Science and Technology
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• 제7권2호
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• pp.179-184
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• 2016

The interface between the surface of a cathode material and the electrolyte gives rise to surface reactions such as solid electrolyte interface (SEI) and chemical side reactions. These reactions lead to increased surface resistance and charge transfer resistance. It is consequently necessary to improve the electrochemical characteristics by suppressing these reactions. In order to suppress unnecessary surface reactions, we coated cathode material using polypropylene (PP). The PP coating layer effectively reduced the SEI film that is generated after a 4.3 V initial charging process. By mitigating the formation of the SEI film, the PP-coated Li[(Ni_0.6Co_0.1Mn_0.3)_0.36(Ni_0.80Co_0.15Al0.05)_0.64)]O₂(NCS) electrode provided enhanced transport of Li⁺ ions due to reduced SEI resistance (R_SEI) and charge transfer resistance (R_ct). The initial charge and discharge efficiency of the PP-coated NCS electrode was 96.2 % at a current density of 17 mA/g in a voltage range of 3.0 ~ 4.3 V, whereas the efficiency of the NCS electrode was only 94.7 %. The presence of the protective PP layer on the cathode improved the thermal stability by reducing the generated heat, and this was confirmed via DSC analysis by an increased exothermic peak.