• Applied Microscopy
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• v.45 no.1
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• pp.16-22
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• 2015

The reaction kinetics of the growth of Ni germanide in the Ni/Zr-interlayer/Ge system was investigated using isothermal in situ annealing at three different temperatures in a transmission electron microscope. The growth rate of Ni germanide in the Ni/Zr-interlayer/Ge system was determined to be diffusion controlled and depended on the square root of the time, with the activation energy of $1.04P{\pm}0.04eV$. For the Ni/Zr-interlayer/Ge system, no intermediate or intermixing layer between the Zr-interlayer and Ge substrate was formed, and thus the Ni germanide was formed and grew uniformly due to Ni diffusion through the diffusion path created in the amorphous Zr-interlayer during the annealing process in the absence of any intermetallic compounds. The reaction kinetics in the Ni/Zr-interlayer/Ge system was affected only by the Zr-interlayer.

• Corrosion Science and Technology
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• v.14 no.6
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• pp.301-312
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• 2015

Corrosion of zirconium fuel cladding is known to limit the lifetime and reloading cycles of fuel in nuclear reactors. Oxide layers formed on ZIRLO4^{TM}$ cladding samples, after immersion for 300-hour and 50-day in a simulated primary water chemistry condition ($360^{\circ}C$ and 20 MPa), were analyzed by using the scanning transmission electron microscopy (STEM), in-situ transmission electron microscopy (in-situ TEM) with the focused ion beam (FIB) technique, and X-ray diffraction (XRD). Both samples (immersion for 300 hours and 50 days) revealed the presence of the ZrO sub-oxide phase at the metal/oxide interface and columnar grains developed perpendicularly to the metal/oxide interface. Voids and micro-cracks were also detected near the water/oxide interface, while relatively large lateral cracks were found just above the less advanced metal/oxide interface. Equiaxed grains were mainly observed near the water/oxide interface.

• Applied Microscopy
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• v.36 no.spc1
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• pp.19-24
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• 2006

The alumina-aluminum solid-liquid interfaces were directly observed at atomic scale by heating the alumina single crystal in high-voltage electron microscope (HVEM) owing to the electron beam damage processes, Atomic ordering in the first several layers of the liquid was clearly resolved adjacent to the alumina surface and its relevance to the single crystal growth was examined with the real-time observations.

• Applied Microscopy
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• v.49
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• pp.3.1-3.7
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• 2019

Graphene, which is one of the most promising materials for its state-of-the-art applications, has received extensive attention because of its superior mechanical properties. However, there is little experimental evidence related to the mechanical properties of graphene at the atomic level because of the challenges associated with transferring atomically-thin two-dimensional (2D) materials onto microelectromechanical systems (MEMS) devices. In this study, we show successful dry transfer with a gel material of a stable, clean, and free-standing exfoliated graphene film onto a push-to-pull (PTP) device, which is a MEMS device used for uniaxial tensile testing in in situ transmission electron microscopy (TEM). Through the results of optical microscopy, Raman spectroscopy, and TEM, we demonstrate high quality exfoliated graphene on the PTP device. Finally, the stress-strain results corresponding to propagating cracks in folded graphene were simultaneously obtained during the tensile tests in TEM. The zigzag and armchair edges of graphene confirmed that the fracture occurred in association with the hexagonal lattice structure of graphene while the tensile testing. In the wake of the results, we envision the dedicated preparation and in situ TEM tensile experiments advance the understanding of the relationship between the mechanical properties and structural characteristics of 2D materials.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1081-1086
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• 2005

Dynamic behavior of carbon nanotubes (CNTs) in an electric field is directly observed by in-situ transmission electron microscopy (TEM). The CNT field emitters examined by in-situ TEM are multiwalled, double-walled and single walled CNTs. Threshold fields for electron emission and sustainable emission currents depending on the structure of CNTs are presented, and degradation mechanism of the CNT field emitters is discussed. In addition to the microscopy studies on individual CNTs, our recent development in surface treatment of CNT layers grown by chemical vapor deposition, which brings about high density of emission current and high uniformity, is also presented.

• Clean Technology
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• v.19 no.3
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• pp.327-332
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• 2013

Space- and time-resolved in-situ optical and fluorescence microspectroscopy techniques have been applied to investigate the coke formation during aromatization of C5 paraffin and olefin over H-ZSM-5 crystal. In-situ UV/vis absorption measurement offers space- and time-resolved information for the coke formation. Different coking trends have been observed with respect to the location of a crystal as well as the reactant types. From in-situ confocal fluorescence microspectroscopy study, it is revealed that the concentration of certain species photo-excited at 488 nm becomes high at the central region, whereas the compounds emitting fluorescence by 561 nm laser move towards the boundary region of the crystal. The different fluorescence patterns obtained varying excitation lasers suggest the existence of distinct fluorescence emitting species having different degree of coke growth.

• Applied Microscopy
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• v.50
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• pp.19.1-19.9
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• 2020

Deformation twinning, one of the major deformation modes in a crystalline material, has typically been analyzed using generalized planar fault energy (GPFE) curves. Despite the significance of these curves in understanding the twin nucleation and its effect on the mechanical properties of crystals, their experimental validity is lacking. In this comparative study based on the first-principles calculation, molecular dynamics simulation, and quantitative in-situ tensile testing of Al nanowires inside a transmission electron microscopy system, we present both a theoretical and an experimental approach that enable the measurement of a part of the twin formation energy of the perfect Al crystal. The proposed experimental method is also regarded as an indirect but quantitative means for validating the GPFE theory.

• Applied Microscopy
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• v.48 no.4
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• pp.128-129
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• 2018

Soft ferromagnetic materials are utilized for various electromagnetic devices such as magnetic recording heads and magnetic shielding. In situ observation of magnetic microstructures and domain wall motions are prerequisite for understanding and improving their magnetic properties. In this work, by the Fresnel (out-of-focus) method of Lorentz microscopy, we observe the domain wall motions of polycrystalline Ni/Ti thin film layers triggered by single-shot laser pulse. Random motions of domain walls were visualized at every single pulse.

• 한국전자현미경학회:학술대회논문집
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• 2005.11a
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• pp.95-98
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• 2005

• Korean Journal of Veterinary Research
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• v.36 no.4
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• pp.845-858
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• 1996

The purpose of this study was to establish early diagnostic methods for the detection of Aujeszky's disease viral antigens and nucleic acid in nasal cells, and buffy coats from experimentally infected living pigs by a combination of immunocytochemistry, in situ hybridization with digoxigenin(DIG)-labled probe and electron microscopy. Forty days old piglets were inoculated intranasally with $10^{7.0}TCID_{50}$ of Aujeszky's disease virus (ADV, NYJ-1-87 strain). The viral antigens and nucleic acid of ADV were detected in nasal cells, and buffy coat for 20 days after inoculation by immunocytochemistry, in situ hybridization with DIG-labeled probe and electron microscopical method. The results were compared with conventional methods such as a porcine Aujeszky's disease serodiagnostic(PAD) kit, neutralization test(NT) and virus isolation. 1. The viral antigens, nucleic acids and capsids of ADV were detected in nasal cells, buffy coats from 3 days to 20 days after inoculation by immunocytochemistry, in situ hybridization with DIG-labeled probe and electron microscopy, respectively. 2. When viral antigens were detected by the immunocytochemical technique, a diffuse brown deposit was observed in the nucleus and cytoplasm of nasal cells, buffy coats and PK-15 cells under a microscope. 3. DIG-labeled DNA probe was prepared by amplification of conserved sequence of recombinant ADV-gp50 clone with polymerase chain reacction. When ADV-DNA was detected by ISH with DIG-labeled probe, purplish blue pigmentation were observed in the nuclei and cytoplasms of ADV-infected cells under a microscope. Positive signals were observed in nasal cells and in the buffy coat and PK-15 cells at the first day after inoculation. 4. Where ADV-capsids were detected by transmission electron microscopical method, aggregation of capsids was observed in the nuclei and cytoplasms of nasal cells, buffy coats and PK-15 cells. The results suggested that these methods were considered as the highly sensitive and reliable tools for rapid and confirmative diagnosis of Aujeszky's disease in living pigs.