• Journal of the Korean Ceramic Society
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• v.38 no.11
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• pp.1008-1014
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• 2001

Nanosize YIG powders added by Cerium which is exellent element in magneto-optical effect were synthesized by Sol-Gel method using Ethylene Glycol solvent. In 120 to 150 minute reaction time, stable sol solution which showed no change in viscosity, pH, and aging time was obtained. Monolithic YIG was synthesized at 80$0^{\circ}C$ with DTA and XRD measurement and its lattice parameter had a tendency to increase from 12.3921 $\AA$. Increasing annealing temperature from 80$0^{\circ}C$ to 105$0^{\circ}C$, average particle size was in the range of 40 nm to 330 nm. Saturation magnetization (M$_{s}$) value was increased from 18.37 to 21.25 emu/g due to enhancement of YIG crystallity and decreasing of orthoferrite phase. On the other hand, coercivity (H$_{c}$) value increased up to 90$0^{\circ}C$ and then decreased above 90$0^{\circ}C$. With increasing Ce addition, coercivity was almost not changed but saturation magnetization value was maximum at Ce 0.1 mol% and then decreased because of increasing a orthoferrite amount. Also, curie temperature (T$_{c}$) of YIG were not changed with Ce addition.ion.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.1
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• pp.65-69
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• 2003

Microstructural and electromagnetic properties of YIG ferrites, (Y, Ca)-(Fe, V, In, Al)-O for Isolator/Circulator were investigated with the sintering temperature. YIG ferrites of $Y_{2.1}Ca_{0.9}Fe_{4.4}V_{0.5}In_{0.05}Al_{0.05}O_{12}$ were fabricated by sintering at $1300^{\circ}C$, $1330^{\circ}C$, $1350^{\circ}C$, $1370^{\circ}C$. Crystallographic and microstructural properties were measured using XRD and SEM. Saturation magnetization$(4{\pi}M_s)$ were measured using VSM, and FMR(Ferromagnetic Resonance) experiment was conducted to measure ferromagnetic resonance line width$({\Delta}H)$. Microwave characteristics of YIG ferrites were measured using a Network Analyzer. The YIG ferrite of $Y_{2.1}Ca_{0.9}Fe_{4.4}V_{0.5}In_{0.05}Al_{0.05}O_{12}$, sintered at $1350^{\circ}C$, showed higher density, saturation magnetization and lower ferromagnetic resonance line width than those sintered at any other temperature.

• Journal of the Korean Ceramic Society
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• v.40 no.1
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• pp.62-68
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• 2003

Ba-ferrite particles added with Co and Ti, which were known well the additives for the control in coercivity, were synthesized by sol-gel method. In the range 90 to 120 minute reaction time, a stable sol solution which showed no change with temperature, pH, viscosity and aging time. After dried and heat treatment of sol solution, Ba-ferrite phase formed at $700^{\circ}C$ with Differential Thermal Analysis(DTA) and X-Ray Diffractometer(XRD) measurement. The crystallinity became to be better with increasing the temperature. It were showed by Scanning Electron Microscopy(SEM) that Ba-ferrite increased to particle sizes as increasing heating temperature and obtained of narrow particles size distribution. Also, magnetic characteristics of Ba-ferrite powders Co and Ti added were observed by a Vibrating Sample Magnetometer(VSM). Saturation magnetization$(M_s)$ was not much changed, however. the coercivity$(H_c)$dramatically dropped with addition of Co and Ti.

• Korean Journal of Materials Research
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• v.11 no.3
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• pp.203-206
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• 2001

The effects of SrTiO$_3$ addition and sintering temperature on the microstructure and magnetic properties of yttrium iron garnet (YIG) were investigated. The lattice Parameter increasing of sintered YlG with small amount of SrTiO$_3$ addition was supposed to be substituted $Y^{+3}$, Fe$^{+3}$ ions to Sr$^{+2}$,Ti$^{+4}$ ions which are relatively large in ionic ranius. A YIG specimen sintered at 142$0^{\circ}C$ with 0.2mol% SrTiO$_3$ showed above 98% densification of theoretical density. Saturation magnetization (M$_s$) at room temperature decreased a little bit with increasing SrTiO$_3$, addition but no great chance. In addition, the coercivity (H$_c$) was almost not changed by sintering temperature.

• Journal of Powder Materials
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• v.10 no.5
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• pp.305-309
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• 2003

We report on the formation and chemical leaching of non-equilibrium $Al_{0.6}(Fe_{75}Co_{25})$ alloy produced by rod milling. X-ray diffractometry, transmission electron microscopy, differential scanning calorimetry, scanning electron microscopy, and vibrating sample magnetometry were used to characterize the as-milled and leached specimens. After 400 h, only the $Al_{0.4}Fe_{0.6}$ peak of the body-centered cubic type was present in the XRD pattern. The entire rod milling process could be divided into three different stages of milling: agglomeration, disintegration, and homogenization. The saturation magnetization, $M_s$ decreased with increased milling time, the $M_s$ of the powders before milling was about 113.8 emu/g, the $M_s$ after milling for 400 h was about 11.55 emu/g. Leaching of the Al in KOH of the Al at room temperature from the as-milled powders did not induce any significant change in the diffraction pattern. After the leached specimen had been annealed at $600^{\circ}C$ for 1 hour, the nanoscale crystalline phases were transformed into the bcc Fe, cubic Co, and $CoFe_2O_4$ phases. On cooling the specimen from 85$0^{\circ}C$, the degree of magnetization increased slightly, then increased sharply at approximately 364.8$^{\circ}C$, indicating that the bcc $Al_{0.4}Fe_{0.6}$ phase had been transformed to the Fe and Co phases.

• Journal of Magnetics
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• v.19 no.1
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• pp.1-4
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• 2014

We report the correlation between the magnetic properties and lattice parameter of $Fe_xCo_{100-x}$ alloys as a function of constituent concentration. The saturation magnetization increases with Fe content and has a maximum value at approximately x=70 at.%. However, collapse in relative saturation magnetization is observed at approximately 30 at.% to 70 at.% of Fe in $Fe_xCo_{100-x}$ alloys. The collapse is due to the formation of Co-Co and Fe-Fe antibonding states instead of Fe-Co bonds. The lattice parameter also shrinks at approximately 30 at.% to 70 at.% of Fe. This shrinkage is due to an increase in the number of nearest neighbor antisite atoms, which then leads to a decrease in the long range order parameter.

• Journal of the Korean Magnetics Society
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• v.9 no.2
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• pp.85-90
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• 1999

The ferromagnetic resonance study of the magnetostatic wave modes for an YIG thin film, grown by a liquid phase epitaxy method, was performed by an FMR spectrometer at room temperature. The magnetostatic surface wave and backward volume wave modes show periodic excitations in parallel configuration, whereas the complex spectra were observed in perpendicular configuration. The resonance spectra in parallel configuration can be well explained by the Walker and Damon-Eshbach theory. The peak-peak line width of uniform mode was 0.4 Oe. The saturation magnetization $M_s$ of the YIG thin film was calculated as 137 emu/㎤. In order to know the dependence of the magnetostatic modes as a function of the saturation magnetization and the thickness, the (1,1) and (3,1) modes of the magnetostatic backward volume wave were compared and theoretically calculated.

• Journal of the Korean Magnetics Society
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• v.10 no.2
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• pp.49-52
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• 2000

The changes of magnetic properties in neutron irradiated F $e_{81}$ $B_{13.5}$S $i_{3.5}$ $C_2$ amorphous ribbon were studied by X-ray diffraction, hysteresis loop, temperature dependence of magnetization and complex permeability. The fluences of thermal ( $n_{th}$) and fast ( $n_{f}$) neutron were 6.95$\times$10$^{18}$ $n_{th}$ c $m^{-2}$ and 4.56$\times$10$^{16}$ $n_{f}$c $m^{-2}$ , respectively. The changes of XRD Profiles were not observable at the neutron irradiated sample. The complex permeability spectra showed that the permeability from domain wall motion decreased due to the increase of pinning force against domain motion by the neutron irradiation, and the relaxation frequency of rotational magnetization moved to higher frequency region. The measurement of hysteresis loop showed the increase of magnetic softness, related to rotational magnetization, but saturation magnetization was decreased in neutron irradiation sample. The Curie temperature was decreased in the neutron irradiated sample.e.e.e.

• Journal of the Korean Vacuum Society
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• v.8 no.4A
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• pp.461-464
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• 1999

Planar type thin film inductors have a potential for the application of miniaturized DC-DC converters. For those high current applications, the magnetic film with high current capability is required. The current capability of magnetic films is mainly determined from high saturation magnetization (4$\piM_s$) as well as large anisotropy field $(H_k)$. We fabricated a double rectangular spiral thin film inductor which consist of magnetic layer, coil and insulator. Highest inductance values as well as best frequency characteristics can be obtained from 5 MHz and quality factor exhibit about 7.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.14-15
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• 2002

Iron nitride alloy films prepared in the form of laminated ${(Fe_{97}Al_3)}_{85}N_{15}/Al_2O_3$ multilayers (Ml's) due to excellent soft magnetic properties and high saturation magnetization [1, 2] are very promising materials for poles and shields in ultra high density thin film heads. The present work concerns the ferromagnetic (FM) coupling effect as a function of the thickness of $Al_2O_3$ spacers by analysis of the magnetic domain structure.