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김창섭,박헌용,양연화,김지영,성백석,김건,Kim, Chang-Seob,Park, Heon-Yong,Liang, Lianhua,Kim, Ji-Young,Seong, Baek-Seok,Kim, Keon 한국전기화학회 2007 한국전기화학회지 Vol.10 No.1
최근 높은 에너지 밀도를 갖고 있는 리튬 이온 이차전지에 대한 관심이 높다. 리튬 이온 이차전지는 이미 휴대용 기기로 널리 적용되고 있으며, 하이브리드 전기자동차와 같은 고출력 전지시스템에 적용을 위해 연구되고 있다. 리튬 이온 이차전지의 전극 소재는 리튬 이온의 이동에 의해서 충전 및 방전되는 현상을 활용한다. 전극으로부터 리튬 이온이 이동될 때 전극내의 구조 변화가 발생한다. 전극의 구조분석은 중성자 또는 X-선을 이용하여 분석할 수 있다. X-선은 분석 시간이 짧고, 쉽게 분석할 수 있다는 장점이 있으나 원자내의 전자구름과의 산란을 응용하므로 전자가 적은 가벼운 원소의 경우 분석이 어려운 단점이 있다. 리튬도 원자량이 작아서 X-선 만으로는 리튬의 정확한 위치에 대한 분석이 어렵다. 중성자 분석기술은 이에 대한 해답이 될 것이다. 본 자료에서는 중성자를 활용한 전극물질의 구조 분석 사례 및 그 원리에 대해서 논의하고자 한다. Lithium ion secondary battery has been applied widely to portable devices, and has been studied for application to high power electric cell system such as power tool or hybrid electronic vehicle. The structure change of the electrodes materials occur when lithium ions move between electrodes. Neutron or X-rays can analyze the structure of electrode. The advantage of X-rays is convenient in test. However X-rays is scattered by electron cloud in atoms. Therefore, The elucidation for correct position of lithium is difficult with X-rays because lithium has small atomic weight. Neutron analysis techniques could solve this problem. In this review, We wish to discuss about structure analysis and the principle of structural characterization method using neutron beam source.
Synthesis and Crystal Structure of Yttria-Stabilized Zirconia
김원사,서일환,박로학,김문집,김헌준,이창희,김용채,성백석,이정수,심해섭,김이경,이진호,Kim, Won-Sa,Suh, Il-Hwan,Bak, Ro-Hak,Kim, Moon-Jib,Kim, Huhn-Jun,Lee, Chang-Hee,Kim, Yong-Che,Seong, Baek-Seok,Lee, Jeong-Soo,Shim, Hae-Seop,Kim, Yi-Kyu 한국지구과학회 1997 韓國地球科學會誌 Vol.18 No.6
등축정계의 결정구조를 지니는 무색 투명한 저코니아($Zr_{0.73}Y_{0.27}O_{1.87}$) 결정을 $Y_2O_3$를 안정제로 사용하여 Bridgman-Stockbager법(또는 Skull 용융법)으로 합성하였다. 육성된 결정은 유리광택을 나타내며 동시에 약간의 지방 광택도 띤다. 저코니아 결정은 편광현미경하에서 등방성을 나타내며 이방성의 징후는 발견되지 않는다. 모스 경도는 $8{\sim}8\frac{1}{2}$이고 비중은 5.85이다. 자외선하에서는 약한 백색 형광을 낸다. 단결정법으로 결정한 저코니아의 결정구조는 등축정계이며, 공간군은 $Fm3m({O^5}_h)$이다. 단위포 상수(a)는 $5.1552(5){\AA}$이며, $V=136.99(5){\AA}$, Z=4, R=0.0488이다. 저코니움 원자는 각 모서리에 산소 원자가 자리잡고 있는 육면체의 중심에 위치하고 있으며, 각 산소 원자는 저코니움 원자로 되어 있는 사면체의 중심에 위치하고 있다. 결국 8:4의 배위수가 성립하는 구조를 하고 있다. Colorless and transparent cubic zirconia($Zr_{0.73}Y_{0.27}O_{1.87}$) crystal has been synthesized by the Bridgman-Stock-bager method(also called Skull melting method). $Y_2O_3$ is used as stabilizer. The crystal shows a vitreous luster with a slight oily appearance. Under a polarizing microscope, it shows isotropic nature with no appreciable anisotropism. Mohs hardness value is measured to be $8{\sim}8\frac{1}{2}$ and specific gravity 5.85. Under ultraviolet light it shows a faint white glow. The crystal structure of yttria stabilized zirconia was determined, using single crystal X-ray diffraction techniques to be a cubic symmetry, space group $Fm\overline{3}m({O^5}_h)$ with $a=5.1552(5){\AA}$, $V=136.99(5){\AA}^3$, Z=4, and R=0.0488 for 29 unique reflections. Each zirconium atom is at the center of eight oxygen atoms situated at the corners of a surrounding cube and each oxygen atom is at the center of a tetrahedron of zirconium atoms. So a coordination of 8:4 holds in the structure.
중성자 회절법에 의한 Ni-W 합금 소결체의 격자상수 측정
김찬중,김민우,박순동,전병혁,장석원,성백석,Kim, Chan-Joong,Kim, Min-Woon,Park, Soon-Dong,Jun, Byung-Hyuk,Jang, Serk-Won,Seong, Baek-Seok 한국분말야금학회 2008 한국분말재료학회지 (KPMI) Vol.15 No.3
Ni-W(1-5 at.%) alloy rods were made by powder metallurgy process including powder mixing, compacting and subsequent sintering. Ni and W powder of appropriate compositions were mixed by a ball milling and isostatically pressed in a rubber mold into a rod. The compacted rods were sintered at $1000^{\circ}C-1150^{\circ}C$ at a reduced atmosphere for densification. The lattice parameters of Ni-W alloys were estimated by a high resolution neutron powder diffractometer. All sintered rods were found to have a face centered cubic structure without any impurity phase, but the diffraction peak locations were linearly shifted with increasing W content. The lattice parameter of a pure Ni rod was $3.5238{\AA}$ which is consistent with the value reported in JCPDS data. The lattice parameter of N-W alloy rods increased by $0.004{\AA}$ for 1 atomic % of W, which indicates the formation of a Ni-W solid solution due to the substitution of nickel atoms by tungsten atoms of larger size.
Four-circle Diffractometer를 이용한 결정방위행렬과 단위포상수 결정
서일환,이진호,심해섭,이정수,성백석,이창희,김문집 순천향대학교 기초과학연구소 1999 순천향자연과학연구 논문집 Vol.5 No.2
A theoretical process to determine the unit cell parameters a, b, c, , β, γ of single crystals and then to collect intensities of ?? using four-circle diffractometer has been shown.
중성자 회절을 이용한 Al 판재의 집합조직 해석과 측정의 정확성
이문규,김성진,이창희,신은주,성백석,박노진 대한금속재료학회(대한금속학회) 2000 대한금속·재료학회지 Vol.38 No.10
The neutron diffraction method is a powerful technique for the texture investigation owing to its high penetration capability, when compared with the X-ray diffraction method. The complete pole figures can be measured and the whole through-thickness texture can be analysed with the neutron diffraction method. Accordingly, the texture measured by means of the neutron diffraction is successfully applied to evaluate the anisotropic properties of the textured materials. Cold rolling of aluminum sheets was carried out with and without lubrication to investigate the formation of inhomogeneous textures as well as to compare the both measurement techniques (neutron and X-ray). The texture of the cold rolled aluminum sheets mainly resides along β-fiber. However, rolling without lubrication led to the formation of the {001}$lt;110$gt;-orientation at the surface layer which was clearly confirmed by X-ray diffraction. With neutron diffraction the whole through-thickness textures were measured. Accuracy of the measurement and texture analysis was estimated using such parameters as RP_(hkl), RP1_(hkl)-value, PF_(hkl)-dispersion and ΔC. It is proved that the texture analysis by the neutron diffraction is more accurate than that by the X-ray diffraction.
徐日煥,李正秀,李珍昊,秋錦洪,成百石,林星秀,柳保盈 충남대학교 자연과학연구소 1992 忠南科學硏究誌 Vol.19 No.2
三斜晶系에는 2個의 空間群이 있고 單斜晶系에는 13個의 空間群이 있다. 本 論解에서는 이 空間群들을 誘導한후 各 空間群에 屬한 一般位置, 原點移動, 特殊座標 및 反射條件들을 說明 하였다. There are two and thirteen space groups in triclinic and monoclinic systems respectively. After derivation of the space groups, the general coordinates, the special coordinates and the reflection conditions of each space group have been discussed and change of origin of certain space groups is also shown.
Suh, Il-Hwan,Choo, Geum-Hong,Lee, Jin-Ho,Lee, Jeong-Soo,Lim, Sung-Su,Ryu, Bo-Young,Seong, Baek-Seok 충남대학교 자연과학연구소 1992 忠南科學硏究誌 Vol.19 No.2
六方晶格子의 點群 3 ̄ml(H)와 6/mmm에 屬한 結晶의 a- 및 b-軸을 따라 撮影한 振動寫眞에는 零層線에 對하여 鏡面對稱이 있다. The existence of the mirror symmetry with respect to the zeroth layer line in the oscillation photographs along a- or b-axis of hexagonal lattices belonging to the point groups 3 ̄ml and 6/mmm has been shown.
이창희,김헌준,이정수,전병칠,호종화,성백석,김용채,심해섭,최병훈 대한금속재료학회(대한금속학회) 1991 대한금속·재료학회지 Vol.29 No.8
The elastic compliance and stiffness constants for hexagonal polycrystalline materials with sheet and fiber texture are calculated in Reuss-Voigt-Hill approximation by averaging corresponding properties of the single cystal weighted with the crystallites orientation distribution function(ODF). They depend only on the first five coefficients in the series expansion of ODF for sheet texture and two for fiber texture. Based on the ODF coefficients obtained by neutron diffraction, anisotropy of Young's modulus was estimated for Zircaloy-4 sheet and tube samples as well as a Zircaloy-2 rod sample.