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Mossbauer 분광법에 CoCrxFe₂-xO₄의 연구
채광표(Kwang Pyo Chae),이혁진(Hyuck Jin Lee),이재광(Jae Gwang Lee),이성호(Sung Ho Lee),이영배(Young Bae Lee) 한국자기학회 2000 韓國磁氣學會誌 Vol.10 No.2
The CoCr_xFe_(2-x)O₄(0.0≤x≤1.0) ferrites have been fabricated by sol-gel method. The crystallographic and magnetic properties of the samples were investigated by means of x-ray diffraction, scanning electron microscophy, Mossbauer spectroscopy and vibrating sample magnetometry. The structure of all the samples is cubic spinel type and the lattice constant decrease with increasing Cr content. The substituted Cr ions were located only in the B-site. The particle size also decreases with increasing Cr content. The Mossbauer spectra consist of two sextets due to Fe³+ ions at A- and B sites for 0.0≤x≤0.6, while, a paramagnetic doublet appears for 0.8≤x≤1.0. The magnetic hyperfine field decreases with increasing Cr content. The relaxation spectra was shown at 0.8≤x≤1.0 in CoCr_xFe_(2-x)O₄. The coercivity decreases drastically, while, the saturation magnetization decreases linearly with increasing x.
Cu₁-xGe₁-yFex+yO₃계의 자기적 및 Mossbauer 분광학적 연구
채광표(Kwang Pyo Chae),권우현(Woo Hyun Kwon) 한국자기학회 1999 韓國磁氣學會誌 Vol.9 No.3
Magnetic properties and crystallographic properties of Cu_(1-x)Ge_(1-y)Fe_(x+y)O₃ system were studied by using x-ray diffraction, superconducting quantum interference device (SQUID) and Mossbauer spectroscopy. All the samples have orthorhombic structure and the lattice constants some decreased as the substituted iron contents increasing. The spin-Peierls (SP) transition temperatures of our samples are about 12.5 K and these temperatures lowered as increasing substituted iron contents. The Mossbauer spectra consisted with two Zeeman sextets and one doublet due to Fe³+ ions. The jump up of magnetic hyperfine field of 2nd Zeeman sextet and the increasing of the values of quadrapole splitting and isomer shift of doublet below SP transition temperature could be interpreted with the variation of the superexchange interaction, the symmetry of lattice sites and the covalency of bonds due to the atomic displacements.
Co - Ti으로 치환한 Ba - 페라이트(BaFe₁₂-₂xCoxTixO19)의 결정학적 및 자기적 특성 연구
채광표(Kwang Pyo Chae),이우천(Woo Chun Lee),이재광(Jae Gwang Lee),이성호(Sung Ho Lee),이영배(Young Bae Lee) 한국자기학회 2000 韓國磁氣學會誌 Vol.10 No.4
Crystallographic and magnetic properties of the Co and Ti-doped BaFe_(12-2x)Co_xTi_xO_(19)(0.0≤x≤1.0) system have been investigated by means of x-ray diffractometry, Mossbauer spectroscopy, and vibrating sample magnetometer. The structure of the system was found to be the magnetoplumbite structure, and the lattice parameter a is nearly constant and c increase as the doped Co-Ti contents increasing. We found that the saturation magnetization nearly unchanged but the coercivity rapidly decreased between x=0.0 and x=0.2 with increasing x in BaFe_(12-2x)Co_xTi_xO_(19). From the Mossbauer spectra analysis Co-Ti ions prefer 12k, 4fvi and 2b sites.
Orthoferrite LaFeO₃에서의 Mn 치환 효과
채광표(Kwang Pyo Chae),이성환(Sung Hwan Lee),이성호(Sung Ho Lee),이영배(Young Bae Lee) 한국자기학회 2000 韓國磁氣學會誌 Vol.10 No.2
Crystallographic and magnetic properties of the Mn-doped orthoferrite LaFe_(1-x)Mn_xO₃ (0.0≤x≤0.4) system have been investigated by means of x-ray diffractometry, Mossbauer spectroscopy, vibrating sample magnetometer and superconducting quantum interference device. The structure of the system was found to be orthorhombic distorted perovskite structure. At room temperature, the Mossbauer spectra for x=0.0 consists of one Zeeman sextets from Fe³+ ions at octahedral sites. The Mossbauer spectra of two Zeeman sextets (x≤0.1) change one Zeeman sextets and a paramagnetic doublet (x=0.4). The saturation magnetization increases but the coercivity decreases with increasing x in LaFe_(1-x)Mn_xO₃.
Mossbauer 분광법에 의한 Al0.2CoFe1.8O₄ 분말의 자기적 특성 연구
채광표(Kwang Pyo Chae),이재광(Jae-Gwang Lee),권혁수(Hyuck Su Kweon),이영배(Young Bae Lee) 한국자기학회 2003 韓國磁氣學會誌 Vol.13 No.6
The Al_(0.2)CoFe_(1.8)O₄ ferrite powders have been prepared by the sol-gel method. The crystallographic and magnetic properties of the sample depending on annealing temperature have been investigated by means of x-ray diffraction, FE SEM, Mossbauer spetroscopy and vibrating sample magnetometry. The x-ray diffractions of all samples annealing temperature above 873 K clearly indicate the presence of spinel structure, the lattice constant decrease from 8.425 Å at 873 K to 8.321 Å at 1073 K, whereas the particle size rapidly increase from about 39 ㎚ at 673 K to about 108 ㎚ at 1073 K. The Mossbauer spectra annealed above 873 K could be fitted as the superposition of two sextets due to Fe³+ at A-site and B-site. The isomer shift (IS) and quadruple splitting (QS) values nearly constant with annealing temperature, whereas magnetic hyperfine field (Hhf) of A-site slowly in crease and that of B-site fastly increases with increasing annealing temperature. The magnetic behaviour of powders shows that the saturation magnetization increase from 0.7 emu/g at 473 K to 72.1 emu/g at 1073 K while the coercivity decrease from 0.951 kOe at 673 K to 0.374 kOe at 1073 K with increasing annealing temperature.
Mossbauer 분광법에 의한 Co₁+xFe₂-₂xTixO₄ 페라이트 분말의 연구
채광표(Kwang Pyo Chae),정성근(Sung Keun Chung),김원기(Won Ki Kim),이성호(Sung Ho Lee),이영배(Young Bae Lee) 한국자기학회 2000 韓國磁氣學會誌 Vol.10 No.5
Ultra-fine Co_(1+x)Fe_(2-2x)Ti_xO₄ ferrite powders have been prepared by the sol-gel method. The crystallographic and magnetic properties of the sample have been investigated by means of x-ray diffraction, Mossbauer spetroscopy and vibrating sample magnetometry. The formation of nano crystallized particles is confirmed. The x-ray diffractions of all samples with various compositions clearly indicate the presence of spinel structure. The Mossbauer spectra could be fitted as the superposition of two sextets due to Fe³+ at A-site and B-site. The is and QS values nearly constant with substituted Co-Ti contents, whereas Hhf of B-site decreases with increasing Co-Ti substitution in Co_(1+x)Fe_(2-2x)Ti_xO₄. The magnetic behaviour of powders shows that the saturation magnetization and the coercivity decrease with increasing x in Co_(1+x)Fe_(2-2x)Ti_xO₄.
Mossbauer 분광법에 의한 Cu0.95Ge0.95Fe0.1O₃의 연구
채광표(Kwang Pyo Chae),권우현(Woo Hyun Kwon),이영배(Young Bae Lee) 한국자기학회 2000 韓國磁氣學會誌 Vol.10 No.1
Magnetic properties and crystallographic properties of Cu_(0.95)Ge_(0.95)Fe_(0.1)O₃ were studied by using x-ray diffraction, superconducting quantum interference device (SQUID) and Mossbauer spectroscopy. Our sample has orthorhombic structure and the lattice constants are a=4.795 Å, b=8.472 Å, c=2.932 Å. The spin-Peierls (SP) transition temperatures of our sample is 13 K. The Mossbauer spectra consisted with two Zeeman sextets and one doublet due to Fe³+ ions. The Zeeman sextets come from tetrahedral Fe³+ ions and the doublets come from octahedral Fe³+ ions. The jump up of magnetic hyperfine field of 2nd Zeeman sextet and the increasing of the values of quadrupole splitting and isomer shift of doublet below SP transition temperature could be interpreted related with the atomic displacements. The N el temperature is 715 K, the Debye temperature are 540 K for octahedral site and 380 K for tetrahedral site, respectively.
치환된 YIG, Y(3-x)Gd(x)Fe4.8in0.2O12(x=0.2, 0.4, 0.6)계에 관한 Mossbauer 분광학적 연구
채광표 ( Kwang Pyo Chae ),이영배 ( Young Bae Lee ),김한석 ( Han Seok Kim ),이성호 ( Sung Ho Lee ) 건국대학교 기초과학연구소 1995 理學論集 Vol.20 No.-
치환된 yttrium iron garnet Y(3-x)Gd(x)Fe4.8In0.2O12계를 제조하여 X-선 회절법과 Mossabuer분광법을 이용, 결정구조와 초미세 상호작용을 연구하였다. X-선 회절 실험결과 결정구조는 모든 조성비영역에서 cubic garnet 구조를 가지며 격자상수는 조성비 x가 증가함에 따라 약간씩 증가하였다. Mossabuer specturm은 octahedral(a) sites과 두개의 tetrahedral sites(d, d`)의 Fe3+ 이온에 의한 세 개의 Zeeman pattern이 나타났다. 일차적으로 각 이론들의 site 선호도를 고려하여 이온 분포식을 결정하고, 이를 다시 이론적 격자상수 및 실험치와 비교 확인하였다. The Y(3-x)Gd(x)Fe4.8In0.2O12(x=0.2, 0.4, 0.6) systems have been investigated by means of X-ray diffractometry and Mossbauer spectroscopy. The specimens have been found to be the garnet structure in the entire composition range, and the lattice constants slightly increased with increasing x. The Mossbauer spectrum consists of three Zeeman sextets at room temperature, one due to the Fe3+ on octahedral (a) sites and the others due to the Fe3+ on the tetrahedral sites(d, d`), respectively. We firstly have set up the cation distribution considering the site preference of the ions, which has again been compared with the theoretically as well as experimentally confirmed lattice parameters.
Sol Gel 방법으로 제조한 Al0.2CoFe1.8O₄ 분말과 박막의 열처리 효과
채광표(Kwang Pyo Chae),이재광(Jae-Gwang Lee),권혁수(Hyuck Su Kweon),김정훈(Jung Hoon Kim),이영배(Young Bae Lee) 한국자기학회 2005 韓國磁氣學會誌 Vol.15 No.3
The Al_(0.2)CoFe_(1.8)O₄ ferrite films and powders were prepared by the sol-gel method. The crystallographic and magnetic properties of the samples were examined with annealing temperature by X-ray diffraction, Mossbauer spetroscopy and vibrating sample magnetometry. The powder samples showed the presence of spinel structure at annealing temperatures above 673 K, while the film samples indicated the spinel structure above 873 K, also the particle size increased with rising annealing temperatures. The Mossbauer spectra of Al_(0.2)CoFe_(1.8)O₄ powder annealed above 873 K could be fitted as the superposition of two Zeeman sextets due to ferrimagnetic phase. And the spectra of annealed at 673 K exhibited the superposition of ferrimanetic and paramagnetic phase and those of annealed at 473 K showed only a paramagnetic phase. The magnetic behaviour of powders appeared that the coercivity increased until annealed at 673 K but decreased above this temperature. The coercivity of the film samples decreased from 1.084 kOe at 873 K to 0.540 kOe at 1073 K with increasing annealing temperatures.
채광표,Chae, Kwang Pyo The Korean Welding and Joining Society 2005 대한용접·접합학회지 Vol.23 No.5
The effective charge number and the critical current density of electromigration in eutetic SnPb and Pb Free $(SnAg_{3.8}Cu_{0.7)$ flip chip solder bumps are studied. The effective charge number of electromigration in eutectic SnPb solder is obtained as 34 and the critical current density is $j=0.169{\times}({\delta}_{\sigma}/{\delta}_x})\;A/cm^2,\;where\;({\delta}_{\sigma}/{\delta}_x})$ is the electromigration-induced compressive stress gradient along the length of the line. While the effect of electromigration in Pb free solder is much smaller than that in eutectic SnPb, the product of diffusivity and effective charge number $DZ^{\ast}$ has been assumed as $6.62{\times}10^{-11}$. The critical length for electromigration are also discussed.