• 전자공학회논문지A
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• 제29A권9호
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• pp.20-28
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• 1992

Dielectric thin film of N/O ($Si_{3]N_{4}/SiO_{2}$) for high density stacked dynamic-RAM cell was formed by LPCVD and oxidation(dry & pyrogenic oxidation methods) of the top 7nm $Si_{3]N_{4}$ film. The thickness, structure and composition of this film were measured by ellipsometer, high resolution TEM, AES and SIMS. The insulating characteristics(I-V characteristics) were investigated by HP 4145, and the characteristics of TDDB (Time Dependent Dielectric Breakdown) were evaluated by using CCST(Current Constant Stress Time) method. In this experiment, The optimum oxidation condition for preparation of good insulating and TDDB characteristics of N/O film was pyrogenic oxidation at 85$0^{\circ}C$ for 30 minutes. The leakage current was reduced from 400pA to 7.5pA when SiO$_{2}$ film with thickness of 2nm was formed on the top of $Si_{3]N_{4}$ film by the pyrogenic oxidation method.

• Bulletin of the Korean Chemical Society
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• 제31권7호
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• pp.1997-2002
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• 2010

ZnSe and ZnS:Mn nanocrystals were synthesized via the thermal decomposition of their corresponding organometallic precursors in a hot coordinating solvent (TOP/TOPO) mixture. The organic surface capping agents were substituted with EDTA molecules to impart hydrophilic surface properties to the resulting nanocrystals. The optical properties of the water-dispersible nanocrystals were analyzed by UV-visible and room temperature solution photoluminescence (PL) spectroscopy. The powders were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), and confocal laser scanning microscopy (CLSM). The solution PL spectra revealed emission peaks at 390 (ZnSe-EDTA) and 597 (ZnS:Mn-EDTA) nm with PL efficiencies of 4.0 (former) and 2.4% (latter), respectively. Two-photon spectra were obtained by fixing the excitation light source wavelengths at 616 nm (ZnSe-EDTA) and 560 nm (ZnS:Mn-EDTA). The emission peaks appeared at the same positions to that of the PL spectra but with lower peak intensity. In addition, the morphology and sizes of the nanocrystals were estimated from the corresponding HR-TEM images. The measured average particle sizes were 5.4 nm (ZnSe-EDTA) with a standard deviation of 1.2 nm, and 4.7 nm (ZnS:Mn-EDTA) with a standard deviation of 0.8 nm, respectively.

• 자원환경지질
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• 제45권2호
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• pp.189-194
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• 2012

생지화학적 반응으로 생성된 광물은 화학적 혹은 구조적 변화를 보여주고 있다. 이러한 광물형성의 메커니즘을 밝히기 위해서는 고해상도를 가진 전자현미경을 이용한 나노스케일 분석이 불가피 하다. 투과전자현미경에 장착되어있는 전자에너지 손실분광 분석법 (EELS)을 이용하여 미생물-광물반응 시 일어나는 현상을 두 가지의 예를 들어서 설명하고자 한다. 1) 철 환원 박테리아에 의한 논트로나이트 의 일라이트 로의 전이; 2) 자철석의 환원으로 인한 능철석의 형성. 특히 철산화/환원의 정량적 분석을 통하여 시간적 변화에 따른 철 산화도 측정은 생지화학적 광물변화에 대한연구를 용이하게 해준다. 따라서 본 논문은 EELS의 분석방법 및 장점을 소개함을 목적으로 한다.

• 한국산업보건학회지
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• 제8권2호
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• pp.254-263
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• 1998

A worker employed in a serpentine mine was found developed mesothelioma as the first case of Korea in 1997. Asbestos was known as a causative agent for mesothelioma. Thus, asbestos contamination in mines could be a big health threat to those workers who were unknowingly exposed. However, there was no report that any minerals found in Korea contained asbestos. This study was carried out to find the presence of any asbestiform fibers in minerals which could be obtained in Korean mines. We examined fifteen minerals from 44 mines which were suspected contaminated with asbestiform fibers. Asbestiform analysis was done with high resolution transmission electron microscope(TEM), with energy dispersive X-ray spectroscope(EDX) and X-ray diffraction(XRD) analyses. Among asbestiform fibers, chrysotile was found in chrysotile, serpentine, talc and pyrophylite specimens from 11 mines. Tremolite was found in tremolite and talc specimens from three mines. Mordenite was found in zeolite specimens from two mines. Wallastonite and sepiolite were found in wallastonite and sepiolite specimens respectively. Crocidolite, antigorite and actinolite were found from talc specimens. But no asbestiform fiber contaminants were found in doromite, vermiculite, limestone, marble, gypsum, kaolin, and clary specimens. Thus, these asbestiform fibers such as such as chrysotile, tremolite, mordenite, crocidolite, antigorite and actinolite could be the responsible agents for the health hazards such as mesothelioma and other cancers.

• Bulletin of the Korean Chemical Society
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• 제31권9호
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• pp.2547-2552
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• 2010

CdS nano-particulate films were prepared at the air/water interface under Langmuir monolayers of arachidic acid (AA) via interfacial reaction between $Cd^{2+}$ ions in the subphase and $H_2S$ molecules in the gaseous phase. The films were made up of fine CdS nanoparticles with hexagonal Wurtzite crystal structure after reaction. It was revealed that the formation of CdS nano-particulate films depends largely on the experimental conditions. When the films were ripened at room temperature or an increased temperature ($60^{\circ}C$) for one day, numerous holes were appeared due to the dissolution of smaller nanoparticles and the growth of bigger nanoparticles with an improved crystallinity. When the films were ripened further, CdS rodlike nanoparticles with cubic zinc blende crystal structure appeared due to the re-nucleation and growth of CdS nanoparticles at the stacking faults and defect structures of the hexagonal CdS grains. These structures were characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and X-ray diffraction (XRD). These results declare that CdS semiconductor nanoparticles formed at the air/water interface change their morphologies and crystal structures during the ripening process due to dissolution and recrystallization of the particles.

• Corrosion Science and Technology
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• 제9권2호
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• pp.81-86
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• 2010

The mechanisms of selective oxidation of intercritically annealed CMnAl TRIP steels in a Continuous Galvanizing Line (GCL) were studied by cross-sectional observation of the surface and sub-surface regions by means of High Resolution Transmission Electron Microscopy (HR-TEM). The selective oxidation and nitriding of an intercritically annealed CMnAl TRIP steel in a controlled dew point 10%$H_2+N_2$ atmosphere resulted in the formation of c-xMnO.$MnO_2$ (1${\leq}$x<3) and c-xMnO.$Al_2O_3$ ($x{\geq}1$) particles on the steel surface. Single crystal c-xMnO.$SiO_2$ ($2{\leq}x{\leq}4$) oxide particles were also observed on the surface. A thin film of crystalline c-xMnO.$SiO_2$ (2${\leq}$x<3) and c-xMnO.$Al_2O_3$ ($x{\geq}1$) was present between these particles. In the sub-surface region, internal oxidation, nitriding and intermetallic compound formation were observed. In the first region, large crystalline c-xMnO.$SiO_2$ ($1{\geq}x{\geq}2$) and c-xMnO.$Al_2O_3$ ($x{\geq}1$) oxides particles were present. In the second region, c-AlN particles were observed, and in a third region, small $MnAl_x$ (x>1) intermetallic compound particles were observed.

• 대한금속재료학회지
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• 제49권4호
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• pp.313-320
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• 2011

100 nm-thick hydrogenated amorphous silicon $({\alpha}-Si:H)$ films were deposited on a glass and glass/30 nm Ni substrates by inductively-coupled plasma chemical vapor deposition (ICP-CVD) at temperatures ranging from 100 to $550^{\circ}C$. The sheet resistance, microstructure, phase transformation and surface roughness of the films were characterized using a four-point probe, AFM (atomic force microscope), TEM (transmission electron microscope), AES (Auger electron spectroscopy), HR-XRD(high resolution X-ray diffraction), and micro-Raman spectroscopy. A nano-thick NiSi phase was formed at substrate temperatures >$400^{\circ}C$. AFM confirmed that the surface roughness did not change as the substrate temperature increased, but it increased abruptly to 6.6 nm above $400^{\circ}C$ on the glass/30 nm Ni substrates. HR-XRD and micro-Raman spectroscopy showed that all the Si samples were amorphous on the glass substrates, whereas crystalline silicon appeared at $550^{\circ}C$ on the glass/30 nm Ni substrates. These results show that crystalline NiSi and Si can be prepared simultaneously on Ni-inserted substrates.

• Advances in nano research
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• 제10권2호
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• pp.191-210
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• 2021

To compare the antifungal effect of two nanomaterials (NMs), nanoparticles of zinc oxide were synthesized by a chemical route and zinc oxide-based nanobiohybrids were obtained using green synthesis in an extract of garlic (Allium sativum). The techniques of X-Ray Diffraction (XRD), Infrared (IR) and Ultraviolet Visible (UV-Vis) absorption spectroscopies and Scanning (SEM) and Transmission Electron Microscopies (TEM) were used to determine the characteristics of the nanomaterials synthesized. The results showed that the samples obtained were of nanometric size (< 100 nm). To compare their antifungal capacity, their effect on Cercospora sp. was evaluated. Test results showed that both nanomaterials had an antifungal capacity. The nanobiohybrids (green route) gave an inhibition of fungal growth of ~72.4% while with the ZnO-NPs (chemical route), inhibition was ~87.1%. Microstructural studies using High Resolution Optical Microscopy (HROM) and ultra-structural analysis using TEM carried out on the treated strains demonstrated the effect of the nanofungicides on the vegetative and reproductive structures, as well as on their cell wall. To account for the antifungal effect presented by ZnO-NPs and ZnO nanobiohybrids on the fungi tested, effects reported in the literature related to the action of nanomaterials on biological entities were considered. Specifically, we discuss the electrical interaction of the ZnO-NPs with the cell membrane and the biomolecules (proteins) present in the fungi, taking into account the n-type nature of the ZnO semiconductor and the electrical behavior of the fungal cell membrane and that of the proteins that make up the protein crown.

• 한국광물학회지
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• 제13권2호
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• pp.53-64
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• 2000

Chlorite from the talc deposits in the Chungnam area, Korea, has been studied using electron microprobe analysis and high resolution transmission electron microscopy (HRTEM), Talc orea are hydrothermal alteration products of serpentinite which was originated from ultramafic rocks. Chlorite occurs in close association with talc ores of with the black alteration zone between talc ore bodies and granitic gneiss. It is the most abundant impurity mineral of talc ores. Chlorite in association with talc is characterized by very high but narrow variation in Mg/(Mg+Fe) ratios (0.784~0.951), significant octahedral substitution (-0.200~0.692), wide variation in Al contents (1.085~3.160 / 14 oxygens), and high Cr and Ni contents. It was formed under a very limited but high Mg/(Mg+Fe) condition in close connection with serpentinite. Chlorite in the black alteration zone is characterized by a high Fe content, wide variation in Mg/(Mg+Fe) ratios (0.378~0.852), narrow octahedral substitution (-0.035~0.525), high narrow Al contents (1.468~2.959), and low Cr and Ni contents. It was formed under a low Mg/(Mg+Fe) and relatively Al-rich condition in close connection with county rocks. Two different chemical modes for chlorite suggest two different origins for two different chlorites. Although most of chlorites show typical 14-$\AA$ lattice fringe images under HRTEM, some chlorites show fringe images of 21-$\AA$ (14$\AA$+7$\AA$) spacings within (001) lattice-fringe images of chlorite (14$\AA$). But brown chlorite from the black zone has high Ti and K contents suggesting that mica was the precursor of brown chlorite. Such possibility is also supported by the fact that lattice-fringe images of brown chlorite show 14-$\AA$ chlorite layers in which 10-$\AA$ mica single layer or packets are interlayered. Partial terminations from 3 mica layers to 2 chlorite layers are often observed. It, therefore, is suggested that the chlorite associated with talc ores is a hydrothermal alteration products of serpentinite, whereas the chlorites in the black alteration zone is a hydrothermal alteration product of granitic gnesis under a partial influence of serpentinite.

• 한국융합학회논문지
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• 제8권8호
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• pp.197-202
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• 2017

본 연구는 미라 모발에 존재하는 멜라닌과립의 보존 상태와 모양을 규명하기 위해서 1250kV의 초고압전자현미경(high voltage electron microscope: HVEM)을 사용하여 3차 구조를 분석하였다. 미라 모발에서 피질에 분포하고 있는 멜라닌과립은 큐티클층에 인접한 바깥쪽 피질에 집중적으로 분포하고 있다. 이들 부위에는 다량의 멜라닌과립들이 무리를 지어 존재하고 있어서 현대인의 정상 모발에 있는 멜라닌과립의 분포양상과 뚜렷한 차이점을 나타내었다. 초고압전자현미경으로 ${\pm}60$도의 범위에서 1도 간격으로 촬영한 결과 멜라닌과립은 길쭉한 타원형의 형태로 크기가 다양하게 관찰되었다. 과립의 크기는 단축 직경이 $0.3-0.6{\mu}m$이고, 장축 직경은 $0.5-1{\mu}m$로 측정되었다. 결론적으로 초고압전자현미경은 일반 투과전자현미경보다 높은 해상도와 투과력을 가져서 두꺼운 절편의 생물 시료 구조분석에 용이하다.