• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.70.1-70.1
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• 2012

In-situ X-ray photoelectron spectroscopy (XPS) and infrared (IR) spectroscopy studies of SOFC cathode materials will be discussed in this presentation. The mixed conducting perovskites (ABO3) containing rare and alkaline earth metals on the A-site and a transition metal on the B-site are commonly used as cathodes for solid oxide fuel cells (SOFC). However, the details of the oxygen reduction reaction are still not clearly understood. The information about the type of adsorbed oxygen species and their concentration is important for a mechanistic understanding of the oxygen incorporation into these cathode materials. XPS has been widely used for the analysis of adsorbed species and surface structure. However, the conventional XPS experiments have the severe drawback to operate at room temperature and with the sample under ultrahigh vacuum (UHV) conditions, which is far from the relevant conditions of SOFC operation. The disadvantages of conventional XPS can be overcome to a large extent with a "high pressure" XPS setup installed at the BESSY II synchrotron. It allows sample depth profiling over 2 nm without sputtering by variation of the excitation energy, and most importantly measurements under a residual gas pressure in the mbar range. It is also well known that the catalytic activity for the oxygen reduction is very sensitive to their electrical conductivity and oxygen nonstoichiometry. Although the electrical conductivity of perovskite oxides has been intensively studied as a function of temperature or oxygen partial pressure (Po2), in-situ measurements of the conductivity of these materials in contact with the electrolyte as a SOFC configuration have little been reported. In order to measure the in-plane conductivity of an electrode film on the electrolyte, a substrate with high resistance is required for excluding the leakage current of the substrate. It is also hardly possible to measure the conductivity of cracked thin film by electrical methods. In this study, we report the electrical conductivity of perovskite $La_{0.6}Sr_{0.4}CoO_{3-{\delta}}$ (LSC) thin films on yttria-stabilized zirconia (YSZ) electrolyte quantitatively obtained by in-situ IR spectroscopy. This method enables a reliable measurement of the electronic conductivity of the electrodes as part of the SOFC configuration regardless of leakage current to the substrate and cracks in the film.

• 폴리머
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• 제33권3호
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• pp.263-267
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• 2009

d-PMMA(deuterated poly(methyl methacrylate)) 박막 표면의 친수성을 향상시키기 위해 산소 플라즈마에 노출시켰다. 이 때 모든 조건은 동일하며, 플라즈마에 대한 노출 시간만을 0초에서 180초까지 변화를 주어 노출 시간에 대한 영향을 접촉각과 X-ray 반사율 장치, 중성자 반사율 장치, XPS(X-ray photoelectron spectroscopy)를 이용해 조사하였다. 노출 시간이 증가할수록 물 접촉각은 작아지며, 산소의 조성은 커짐을 확인함으로써 산소의 조성이 친수성 향상에 큰 영향을 미치는 것을 확인할 수 있었다. 또한, X-ray 반사율 장치를 이용해 얻은 에칭률을 통해서 d-PMMA 박막에 대한 산소 플라즈마의 노출 시간에 따른 물리적 특성을 연구하였으며, X-ray 반사율과 중성자 반사율, 그리고 XPS 측정 결과로부터 산소와 탄소의 조성뿐만 아니라 수소의 조성까지도 얻음으로써 플라즈마 처리된 박막의 화학적 성질을 보다 자세히 연구할 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.275-275
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• 2013

Formation and characterization of self-assembled monolayers (SAMs) on various surfaces are the essential basis for many other applications, including molecular switches, biosensors, microfluidics, and fundamental studies in surfaces and interfaces. To improve the performance at these applications, it is a key to control the quantity of each molecule in various mixed SAMs on the surface. In this study, using mixed SAM of carbamate-based hydroquinone (HQ)-PhBr and11-mercaptoundecanol, the quantitative mass spectrometric method of mixed SAM was developed based on comparison study with XPS and FT-IR methods. In addition, our method was applied to another mixed SAM of biotinylated PEG alkane thiol and 11-mercaptoundecanol for verification purpose. Time-of-flight secondary mass spectrometry (ToF-SIMS) analysis was performed to identify and quantify each molecule of mixed SAM along with principal component analysis (PCA). Since there is no matrix effect in the X-ray photoelectron spectroscopy (XPS) and Fourier transform-infrared (FT-IR) techniques, we compared ToF-SIMS results with XPS and FT-IR results. Because PCA results from ToF-SIMS analysis are well matched with XPS and FT-IR results from both mixed SAMs, we are expecting that our method will be useful to identify and quantify each molecule in various mixed SAMs.

• 한국진공학회지
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• 제7권4호
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• pp.320-327
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• 1998

원격 플라즈마 화학기상증착법(Remote Plasma Enhanced-Ultrahigh Vacuum Chemical Vapor Deposition)에 의해 활성화된 질소 원자를 사용하여 사파이어 기판의 표면 을 저온에서 질화처리한 후 표면의 화학적 조성을 조사하였다. 질화처리에 의해 주로 표면 에 형성된 물질은 AIN임을 X-선 광전자 분광방법(X-ray photoelectron spectroscopy:XPS) 을 사용하여 확인하였다. 또한 플라즈마의 RF 출력, 반응 온도 및 시간에 따라서 기판의 Al 과 반응한 질소의 상대적인 양과, 표면 형태를 XPS와 AFM(atomic force microscopy)을 사 용하여 조사하였다. 플라즈마에 의해서 질소는 RF출력에 따라 증가한 후 일정하게 됨을 관 찰하였다. 그러나 질화 처리 온도와 시간의 증가에 따른 AIN의 상대적인 양은 비교적 무관 함을 관찰하였다. 또한 Ar스퍼터링을 통한 XPS의 depth profile을 관찰한 결과 질화층은 깊 이에 따라 3개의 다른 층으로 이루어져 있음을 확인하였다.

• KSTLE International Journal
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• 제2권2호
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• pp.138-141
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• 2001

Tribological behaviors of a borate of triethanolamine in water solution were evaluated using a four-ball wear tester. X-ray photoelectron spectroscopy (XPS) was employed to study tribochemical species on worn scars of steel balls. Results show that a thick deposit layer was produced on the worn scars, which came from the decomposition of the borate. The surface film on the worn scars was mostly consisted with H$_3$BO$_3$, B$_2$O$_3$and large amounts of ferricyanides.

• 통합자연과학논문집
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• 제7권3호
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• pp.183-187
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• 2014

Lead zirconate titanate (PZT) is significant material in electrical and optical devices for their ferroelectric, piezoelectric and dielectric properties. In this research, PZT films were fabricated by reactive RF co-sputtering method using Pb, Zr, and Ti targets. From XPS study, lead, zirconium, and titanium are successfully deposited on Si(100) substrate. Thickness of PZT films was measured with a surface profiler and the thickness was decreased as the oxygen gas ratio increased in the sputter gas.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권5호
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• pp.265-269
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• 2000

$(Ba, Sr)TiO_3$thin films were etched with a magnetically enhanced inductively coupled plasma (MEICP) at different CF4/Ar gas mixing ratios. Experimental was done by varying the etching parameters such as rf power, dc bias and chamber pressure. The maximum etch rate of the BST films was $1800{AA}/min$ under $CF_4/(CF_4+Ar)$ of 0.1, 600 W/350 V and 5 mTorr. The selectivity of BST to Pt and PR was 0.6, 0.7, respectively. X-ray photoelectron spectroscopy (XPS) results show that surface reaction between Ba, Sr, Ti and C, F radicals occurs during the (Ba, Sr)TiO3 etching. To analyze the composition of surface residue after the etching, films etched with different CF_4/Ar$ gas mixing ratio were investigated using XPS and secondary ion mass spectroscopy (SIMS).

• Bulletin of the Korean Chemical Society
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• 제31권2호
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• pp.397-400
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• 2010

Zirconium oxide thin films deposited on the p-type Si(100) substrates by radio-frequency (RF) reactive magnetron sputtering with different plasma gas ratios have been studied by using spectroscopic ellipsometry (SE), atomic force microscopy (AFM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The deposition of the films was monitored by the oxygen gas ratio which has been increased from 0 to 80%. We found that the thickness and roughness of the zirconium oxide thin films are relatively constant. The XRD revealed that the deposited thin films have polycrystalline phases, Zr(101) and monoclinic $ZrO_2$ ($\bar{1}31$). The XPS result showed that the oxidation states of zirconium suboxides were changed to zirconia form with increasing $O_2$ gas ratio.

• 한국결정성장학회지
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• 제13권1호
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• pp.19-23
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• 2003

Polished surface of $CsB_{3}O_{5}$ (CBO) has been observed by reflection high energy electron diffraction (RHEED) and X-ray photoelectron spectroscopy (XPS). For comparison, electronic properties of CBO powder have been studied by XPS. It has been found that the crystal surface is covered by thick amorphous layer with chemical composition closely related to that of CBO. Great enrichment of top surface by cesium, ~30 % in reference to the bulk of the modified layer, has been displayed by depth profiling.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.306.2-306.2
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• 2016

Niobium oxide thin films were synthesized by reactive rf magnetron sputtering. The target was metallic niobium with 2 inch in diameter and the substrate was n-type Si wafer. To control the surface properties of the films, Nb oxide thin films were obtained at various mixing ratios of argon and oxygen gases. Nb oxide thin films were analyzed with alpha step, scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The result of alpha step showed that the thickness of Nb oxide thin films were decreased with increasing the oxygen gas ratios. SEM images showed that the granular morphology was formed at 0% of oxygen gas ratio and then disappeared at 20 and 75% of oxygen gas ratio. The amorphous Nb oxide was observed by XRD at all films. The oxidation state of Nb and O were studied with high resolution Ni 2p and O 1s XPS spectra. And the change in the chemical environment of Nb oxide thin films was investigated by XPS with Ar+ sputtering.