• Applied Microscopy
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• v.50
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• pp.8.1-8.7
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• 2020

Two thickness measurement methods using an electron energy loss spectroscopy (EELS) and 10a convergent beam electron diffraction (CBED) were compared in an Fe-18Mn-0.7C alloy. The thin foil specimen was firstly tilted to satisfy 10a two-beam condition. Low loss spectra of EELS and CBED patterns were acquired in scanning transmission electron microscopy (STEM) and TEM-CBED modes under the two-beam condition. The log-ratio method was used for measuring the thin foil thickness. Kossel-Möllenstedt (K-M) fringe of the $13{\ba{1}}$ diffracted disk of austenite was analyzed to evaluate the thickness. The results prove the good coherency between both methods in the thickness range of 72 ~ 113 nm with a difference of less than 5%.

• Journal of the Korean Ceramic Society
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• v.34 no.2
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• pp.139-144
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• 1997

Structurally, the rare earth cuprate superconductor of Nd2-xCexCuO4-$\delta$ has T' structure and has been known as having a quite complicated microstructural phenomena, so far. In order to be superconductivity, both small amount of cation substitution of Nd3+ by Ce4+ and oxygen reduction are required. In the present study the crystallographic study on the structural transition for the Nd2-xCexCuO4-$\delta$ crystal has been con-ducted by observing the CBED (Convergent Beam Electron Diffraction) pattern with STEM(Scanning Transmission Electron Microscope). Three different samples of Nd2CuO3,Nd1.85Ce0.15CuO4 and Nd1.85Ce0.15CuO3.965 were prepared by solid-state sintering and their CBED patterns were observed by STEM to study the structural transition accompanying the substitution of Ce and the reduction of oxygen. Experimental HOLZ lines of these samples were compared with those plotted by a computer-programmed simulation to de-termine the lattice parameter of Nd2-xCexCuO4-$\delta$ crystal.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.176-177
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• 2014

The new algorithm was proposed to quantify symmetry recorded in convergent beam electron diffraction (CBED) patterns and symmetry mapping. The proposed algorithm is based on the normalized cross-correlation coefficient (${\gamma}$) for quantifying the amount of symmetry in a CBED pattern. The quantification and mapping procedures are automatically controlled by the script implemented in Gatan Digital Micrograph$^{(c)}$. We apply the quantitative CBED measurement to a strained Si sample to test the sensitivity to defects.

• Journal of the Mineralogical Society of Korea
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• v.17 no.4
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• pp.327-338
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• 2004

XRD studies on annealed Na-feldspar (Amelia albite) at $1100^{\circ}C$ showed rapid structural changes due to Si-Al disordering, which resulted in phase transformations from low albite to high albite by 4-days annealing test. TEM SAED analyses on the annealed samples revealed a trend of structural changes, but estimation of the structural state was difficult due to a large deviation of the SAED data. Optimum conditions of CBED analyses on albite was established by employing a cooling specimen holder, 120 kV of acceleration voltage, 37 Jim of condenser aperture size and 25 nm of spot size. A proper orientation showing distinct changes of HOLZ lines corresponding to the structure changes of albite turned out to be close to the [418] direction with $-1.2^{\circ}$ tilting, where the width of two HOLZ lines in low albite was opposite to those in high albite.

• Proceedings of the Mineralogical Society of Korea Conference
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• 2002.05a
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• pp.51-53
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• 2002

• 한국전자현미경학회:학술대회논문집
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• 2001.05a
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• pp.58-60
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• 2001

• 한국전자현미경학회:학술대회논문집
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• 2001.11a
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• pp.83-83
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• 2001

• 한국전자현미경학회:학술대회논문집
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• 1993.06a
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• pp.25-25
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• 1993

• Journal of the Korean Society of Industry Convergence
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• v.4 no.2
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• pp.149-155
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• 2001

The use of primitive cell volume and zero order Laue (ZOLZ) pattern is proposed to identify phase in a complex microstructure. Single convergent beam electron pattern containing higher order Laue zone ring from a nanosized region is sufficient to calculate the primitive cell volume of the phase, while ZOLZ pattern is used to determine the zone axis of the crystal. A computer program is used to screen out possible phases from the value of measured cell volume from convergent beam electron diffraction (CBED) pattern. Indexing of ZOLZ pattern follows in the program to find the zone axis of the identification from a single CBED pattern. An example of the analysis is given from the rapidly solidified $Al-Al_3Ti$ system.

• Analytical Science and Technology
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• v.6 no.5
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• pp.515-520
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• 1993

By the real use of Rene 80 cast blades at high temperature ${\gamma}^{\prime}$ precipitates in the matrix(${\gamma}$) mainly due to the operating temperature. These precipitates play main role for strenthening of the blades. Generally known that dislocation density increases due to ${\gamma}-{\gamma}^{\prime}$ mismatch by the generation and growth of the precipitates, because the lattice parameter of ${\gamma}^{\prime}$ is higher than that of ${\gamma}$. These lattice parameters of ${\gamma}$ and ${\gamma}^{\prime}$ are determined through the CBED(Convergent Beam Electron Diffraction) method by STEM(Scanning Transmission Electron Microscope) in this work. And also studied, whether and how much the dislocation density increases by the generation and growth of the precipitates.