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김응찬(E. C. Kim),이상율(S. R. Lee),김성진(S. J. Kim),한국화(G. H. Han) 한국자기학회 2007 韓國磁氣學會誌 Vol.17 No.1
Ti0.96Co0.02Fe0.02O₂의 자기적 특성을 알아보기 위해 온도와 Ti-getter를 변화시켜 XRD(X-ray Diffraction)와 VSM(Vibrating Sample Magnetometer)을 이용하여 실험하였다. 실험은 먼저 Host 물질로 TiO₂를 사용하고 여기에 두 가지 전이 금속인 Fe와 Co를 첨가하여 직접합성법(solid state reaction)으로 시료를 제작하였다. Ti0.96Co0.02Fe0.02O₂의 결정학적 구조를 알기 위해 XRD 측정을 해 본 결과 tetragonal 구조의 순수 rutile 상을 보였다. 또한 온도에 무관하게 Ti-getter를 넣은 시료는 Fe 2차상이 동일하게 나왔으며, Ti-getter를 넣지 않은 시료는 Fe₂TiO?가 검출 되었다. 그리고 VSM(Vibrating Sample Magnetometer)을 이용하여 자기적 특성을 측정하였다. 상온에서 자기이력곡선(M-H)는 강자성을 보이며, 0.8T에서 CoFe 원자당 자기 모멘트는 약 1.3 ?B/CoFe가 측정 되었다. 그러나 Ti-getter를 넣지 않고 실험한 시료에서는 약 0.02 ?B/CoFe가 측정 되었다. The samples were synthesized by using a solid state reaction. The X-ray diffraction pattern for Ti0.96Co0.02Fe0.02O₂ showed a pure rutile phase with tetragonal structures. Mixtures of the proper proportions of the elements sealed in evacuated quartz ampoule were heated at 870~930 ℃ for one day and then slowly cooled down to room temperature at a rate of 10 ℃/h. In order to obtain single phase material, it was necessary to grind the sample after the first firing and to press the powders into pellets before annealing them for a second time in evacuated and sealed quartz ampoule. Magnetic properties have been investigated using the vibrating sample magnetometer (VSM). Room temperature magnetic hysteresis (M-H) curve showed an obvious ferromagnetic behavior and the magnetic moment per Fe atom under the applied of 0.8T was estimated to be about 1.3 ?B/CoFe. But the magnetic moment per Fe atom under the applied of 0.8T was estimated to be about 0.02 ?B/CoFe without Ti-getter.
Zn<SUB>1−x</SUB>Fe<SUB>x</SUB>O의 뫼스바우어 분광학적 연구
김성진(S. J. Kim),이상률(S. R. Lee),박철수(C. S. Park),김응찬(E. C. Kim),조영걸(Y. G. Joh),김동호(D. H. Kim) 한국자기학회 2008 韓國磁氣學會誌 Vol.18 No.2
Recently, the - semiconductor ZnO, normally n-type, doped with magnetic impurities was reported to be ferromagnetic above room temperature. Since ZnO is optically transparent, ferromagnetic Zno should a transparent magnet as well. The purpose of this study was to carry out Mossbauer, X-ray and magnetic-susceptibility measurements on ZnO<SUB>0.99</SUB>Fe<SUB>0.01</SUB>O to examine its magnetic properties and to separate the contributions of the ferromagnetic and the paramagnetic phases to the magnetization. The X-ray diffraction (XRD) data for Zn<SUB>0.99</SUB>Fe<SUB>0.01</SUB>O showed a typical hexagonal structure, with no indication of a secondary phase. The magnetic hysteresis (M-H) curve at room temperature showed an obvious ferromagnetic behaviour, and the magnetic moment per Fe atom under an applied field of 0.8 T was estimated to be about 2 μB, suggesting a low spin configuration of Fe ions. Mossbauer spectra of Zno<SUB>0.99</SUB>Fe<SUB>0.01</SUB>O have been taken at various temperatures ranging from 100 to 300 K. The Mossbauer spectrum of Zn<SUB>0.99</SUB>Fe<SUB>0.01</SUB>O consists of a ferromagnetic (six-Lorentzian) and a paramagnetic phase (doublet).
Ti-Getter가 Ti<SUB>0.96</SUB>Co<SUB>0.02</SUB>Fe<SUB>0.02</SUB>O₂의 자기적 특성에 미치는 영향
남효덕(H. D. Nam),김성진(S. J. Kim),백종근(J. K. Baek),이상률(S. R. Lee),박철수,김응찬(E. C. Kim) 한국자기학회 2008 韓國磁氣學會誌 Vol.18 No.3
The samples were synthesized by using a solid state reaction. The X-ray diffraction pattern for Ti<SUB>0.96</SUB>Co<SUB>0.02</SUB>Fe<SUB>0.02</SUB>O₂ showed a pure rutile phase with tetragonal structure, Mixtures of the proper proportions of the elements sealed in evacuated quartz ampoule were heated at 870~930 ℃ for one day and then slowly cooled down to room temperature at a rate of 10 ℃/h. In order to obtain single phase material, it was necessary to grind the sample after the first firing and to press the powders into pellets before annealing them for a second time in evacuated and sealed quartz ampoule. Magnetic properties have been investigated using the vibrating sample magnetometer (VSM). Room temperature magnetic hysteresis (M-H) curve showed an obvious ferromagnetic behavior and the magnetic moment per Fe atom under the applied of 0.8 T was estimated to be about 1.5 μB/CoFe. But the magnetic moment per Fe atom under the applied of 0.8 T was estimated to be about 0.02 μB/CoFe without Ti-getter. Size of particles is about 1 ㎛ using the transmission electron microscope (TEM). The ingredients of sample are distributed irregular in particles. Only Fe get shown on the surface of particles.
Ni₁-xZnxFe₂O₄(0≤x≤1) Ferrite의 자기적 성질 연구
조익한(I. H. Cho),양재석(J. S. Yang),김응찬(E. C. Kim),강신규(S. G. Kang) 한국자기학회 1996 韓國磁氣學會誌 Vol.6 No.6
The magnetic properties of Ni_(1-x)Zn_xFe₂O₄ have been studied by X-ray diffractometry and Mossbauer Spectroscopy at room temperature. The X-ray diffraction study show that spinel structure is formed in all x, lattice constants linearly increased from 8.3111 Å to 8.4184 Å(± 0.0003) with increasing x from 0 to 1, and oxygen parameter increase with increasing x. Mossbauer spectrum shows that Ni_(1-x)Zn_xFe₂O₄(x=0) has two antiparallel magnetic structure due to Fe³+ octahedral site and Fe³+ tetrahedral site. Ni_(1-x)Zn_xFe₂O₄ with 0.2≤x≤0.6 has magnetic structure of Yafet and Kittel, in particularly, specimen with x=0.6 shows relaxation effect. Specimen with x≥0.8 show paramagnetic quadrupole splitting. The isomer shift is independent of x, but quadrupole splittings decrease with increasing x in the range of 0.8≤x≤1, and nuclear magnetic fields decrease with increasing x in the range of 0≤x≤0.6. The magnetic properties of Ni_(1-x)Zn_xFe₂O₄ change from ferrimagnetics to paramagnetics with increasing x.
Stainless steel공장 발생분진의 효과적인 재활용을위한·분리 ·집진 기술개발
남효덕,김응찬 嶺南大學校 基礎科學 硏究所 1998 基礎科學硏究 Vol.18 No.-
A new concept of magnetic filtering technique was embodied by manufacturing an electromagnetic type magnetic filter. This device has been built and identified as a tool for separating the magnetic oxide. particles from non-magnetic particles produced from stainless steel melting process. Preliminary studies were carried out to conform the filtering recovery as a function of magnetic field strength. The recovery yield of magnetic oxides particles was found to be almost constant regardless of the applied magnetic field as far as both the pair of magnetic poles are parallel each, other. The recovery yield of magnetite oxides such as(Zn, Cu, Fe)(Ni,Fe)O₄composition was 94∼96 wt.% and the rest were non-magnetic oxides in(Fe,Cr)₂O₃, (Fe, Mn)O type or CaO based slags. During the course of present research a ?? spectroscopy to find out an exact composition of magnetic oxides particles has been established.