• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1179-1180
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• 2006

Y-type barium ferrite ($Ba_2Me_2Fe_{12}O_{22};$ Me=Zn, Co, Cu) expected as an electromagnetic wave absorber were prepared by the glass-ceramic method. The glasses with composition of $0.1ZnO{\cdot}0.9(xB_2O_3{\cdot}yBaO{\cdot}(1-x-y)Fe_2O_3)$ were prepared. Single-phase powders of Y type barium ferrite were obtained with the composition $0.1ZnO{\cdot}0.9(0.2B_2O_3{\cdot}0.5BaO{\cdot}0.3Fe_2O_3)$. The shape of Y-type crystals depended strongly on the heating temperature and changed from a plate-like hexagon to a complex polyhedron with increasing heating temperature. Correlation was recognized between saturation magnetization and crystal shape. Electromagnetic wave absorption characteristics was affected by the saturation magnetization and crystal shape.

• Journal of the Korean Ceramic Society
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• v.34 no.1
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• pp.37-44
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• 1997

Barium ferrite thin films on the thermal oxidized Si substrate were prepared by using sol-gel method (dip coating) from the sol of composition ratio of 5.25, designated by mole ratio 2Fe/Ba. The gelation process was largely divided into 4 step, and the sol prepared by reaction for 90 minutes at 8$0^{\circ}C$ was the suit-able for coating. Needle shaped particles formed on the coating layer were placed parallel to substrate and the inclination was increased with film thickness. The easy-direction of magnetization of needle shaped par-ticles was long-axis direction.

• Applied Microscopy
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• v.2 no.1
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• pp.1-6
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• 1972

The Optimum Conditions of Preparing barium Ferrite from $BaCO_3$ and $Fe_2O_3$ are Sought for with electron microscope. At first to find the optimum sintering temperature, the mixture in 1 : 3 mole ratio. Sintered primarily at $700^{\circ}C$ for an hour, is Sintered secondary at $960^{\circ}C{\pm}10,\;1040^{\circ}C{\pm}10,\;1120^{\circ}C{\pm}10,\;1200^{\circ}C{\pm}10,\;1250^{\circ}C{\pm}10,\;1330^{\circ}C{\pm}10$, respectively for an hour. at the optimum temperature,abtained in this way. Sintering time is varied from 10 minutes to 120 minutes with 10 minutes intervals. Through the experiment, It is found that the optimum temperature of $1200{\sim}1250^{\circ}C$ and optimum time of half-one hour.

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.427-428
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• 2000

• Journal of the Korean Magnetics Society
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• v.11 no.3
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• pp.129-133
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• 2001

In this paper, we studied structural and magnetic properties of Ba-ferrite thin film deposited on Si(100) substrate with TiO$_2$ underlayer. Ba-ferrite thin films with TiO$_2$ underlayer were deposited by reactive RF/DC magnetron sputtering system at room temperature. TiO$_2$ underlayer was reactive sputtered with $O_2$. After deposition, the thin films were annealed at vatious temperatures to get the crystallized sample. Underlayer was used to prevent interdiffusion from Ba-ferrite thin film to substrate. The growth of Ba-ferrite thin films was influenced by TiO$_2$ underlayer. Easy magnetization direction is in-plane. From these results the Ba-ferrite film with TiO$_2$ underlayer can be used as longitudinal recording media.

• Journal of the Korean Magnetics Society
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• v.11 no.3
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• pp.122-128
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• 2001

In this paper, we studied structural and magnetic properties of Ba-ferrite thin film deposited on Si(100) substrate with various underlayers. Ba-ferrite thin films with various underlayers were deposited by reactive RF/DC magnetron sputtering system at room temperature. various underlayers was reactive sputtered with O$_2$. After deposition, the thin films were annealed at 850 $^{\circ}C$ to get the crystallized sample. Underlayers were used to prevent interdiffusion from Ba-ferrite thin film to substrate. The growth of Ba-ferrite thin films was influenced by underlayers. Easy magnetization direction is in-plane. From these results the Ba-ferrite film with various underlayers can be used as longitudinal recording media.

• Journal of the Korean Ceramic Society
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• v.34 no.10
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• pp.1045-1052
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• 1997

Barium ferrites (BaFe12O19) were synthesized at the various temperature by the coprecipitation-oxidation method. X-ray diffraction Rietveld analysis for barium ferrites were performed, their microstructures were observed and their magnetic properties were measured, in order to analyze the crystal structures and determine the optimal temperature of heat-treatment. The barium ferrite, its average particle size 80 nm, was formed at 600℃ through the hematite (α-Fe2O3), but the site occupations of the Fe's in tetrahedral and bipyramidal sites and of the Ba relatively low. Increasing the heating temperature, these occupations and the magnetization increased, and the crystal c-axis decreased. These changes were very small at the heat treatment of above 800℃, but the particles were rapidly grown. It is suggested that the optimal temperature of heat-treatment is 800℃, at which temperature crystal structure is relatively stable and the particles hardly ever grow.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1181-1182
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• 2006

Y-type barium ferrite $(Ba_2Zn_2Fe_{12}O_{22})$ was prepared by the glass-ceramic method. Glasses with composition of $0.1ZnO{\cdot}0.9(0.3Fe_2O_3{\cdot}0.5BaO{\cdot}0.2B_2O_3)$ were prepared, and the precipitation behavior of Y-type ferrite from the glass matrix was investigated by heating glass specimens at various temperature. $\alpha-BaFe_2O_4$ which is a precursor of M-type ferrite $(BaFe_{12}O_{19})$ was precipitated at about 813 K and an unknown compound, phase X, was precipitated at about 850 K. M-type ferrite and Y-type ferrite started to form at about 923 K and 1103 K, respectively. The formation of Y-type ferrite was int erpreted as the result of the reaction of M-type ferrite with a melt of phase X.

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.425-426
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• 2000

• Journal of the Korean Magnetics Society
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• v.19 no.1
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• pp.12-16
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• 2009

Z-type barium ferrite [($Ba_{3}Co_{0.8}Zn_{1.2}Fe_{24}O_{41}$, $Ba_{3+{\delta}}Co_{0.8}Zn_{1.2}Fe_{24}O_{41}$ ${\delta}$ = 3, 5, 7, 13 wt%. $Ba_{3}Co_{0.8}Zn_{1.2}Fe_{24+{\delta}}O_{41}$ ${\delta}$ = 5, 7, 10 wt% )] were synthesized using co-precipitation method. The microstructure and magnetic properties of synthesized particles were investigated. In all prepared particles M-type Ba ferrite is identified with Z-type Ba ferrite together. It is found that particles having 7 wt% for Ba and 5 wt% for Fe excess addition revealed high saturation magnetization, respectively. All synthesized particles showed relatively high coercivity for device application. This result may be attributed to the contribution of M-type Ba ferrite. Ba and Fe excess addition was not affected to the structural change of CoZnZ Ba ferrite. The certain amount of excess additions of Ba and Fe and the 2 step heat-treatment may be beneficial to the improvement of soft magnetic properties of Z-type barium hexa-ferrite