• Title/Summary/Keyword: Y-type barium ferrite

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Preparation and Magnetic Properties of Ba-Ferrite Particles Using the Supercritical Water Crystallization Method

  • Nam, Sung-Chan;Kim, Kun-Joong;Park, Sang-Do
    • Proceedings of the Korean Magnestics Society Conference
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    • 2000.09a
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    • pp.433-440
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    • 2000
  • Barium ferrite particles were synthesized from Ba(NO$_3$)$_2$, Fe(NO$_3$)$_3$ and KOH mixed solutions using hydrothermal crystallization in supercritical water. The experimental apparatus for production of barium ferrite is a flow-type apparatus. Fine barium ferrite particles were produced because supercritical water causes the metal hydroxides to be rapidly dehydrated before significant growth takes place. The effects of Fe/Ba ratio and reaction time on the formation, particle size, and magnetic properties of barium ferrite were studied. When Fe/Ba ratio were varied from 0.5 to 12, single-phase barium ferrite powder was only produced in the range of 0.5〈Fe/Ba〈2. Also, with elevating reaction time, the BaO.6Fe$_2$O$_3$ particle size grew smaller. Especially, uniform barium hexaferrite particles of size 100-200nm were obtained at 80sec. In this study, therefore, single-phase barium ferrite particles are highly stable and can be produced continuously in a reaction time of less then 2min.

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Electromagnetic Wave Absorption Characteristics of Y-type Barium Ferrite Prepared by the Glass-ceramic Method

  • Miki, Hiroki;Hori, Chinatsu;Nagae, Masahiro;Yoshio, Tetsuo
    • 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.

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Fabrication of Barium Ferrite Films by Sol-Gel Dip Coating and Its Properties.

  • T. B. Byeon;W. D. Cho;Kim, T. O.
    • Journal of Magnetics
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    • v.2 no.1
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    • pp.16-21
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    • 1997
  • Those were investigated, the crystallographic, morphological, and magnetic properties of barium ferrite film (SiO2/Si substrate) prepared by sol-gel dip coating. Appropriate sol was prepared by dissolvin barium and iron nitrate in ethylene glycol at 80$^{\circ}C$. To obtain the films, thermally oxidized p-type silicon substrate with (111) of crystallographic orientation were dipped into the sol, dried at 250$^{\circ}C$ to remove organic material, and heated at 800$^{\circ}C$ for 3 hours in air for the crystallization of barium ferrite. It was found that the particles of barium ferrite formed on the substrate exhibited needle-like shape placing parallel to the substrate and its c-axis is long axis direction. There was tendency that the coercive force in horizontal direction to the substrate was higher than that in vertical direction to it. This tendency was profound in large thickness.

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Formation Mechanism of Y-type Barium Ferrite Prepared by the Glass-ceramic Method

  • Hori, Chinatsu;Miki, Hiroki;Nagae, Masahiro;Yoshio, Tetsuo
    • 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.

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The Effect of Ba and Fe Concentration on Soft Magnetic Properties of Z-Type Barium Ferrite (Z-Type 바리움 페라이트 분말의 연자성 특성에 미치는 Ba 및 Fe 농도의 영향)

  • Cho, Kwang-Muk;Nam, In-Tak
    • 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

Magnetic and Microwave Absorbing Properties of Ti-and Co-Substituted Barium Ferrite (BaFe12-2X TiXCoXO19)

  • Han-Shin Cho;Yong-Jin Kim;Sung-Soo Kim
    • Journal of Magnetics
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    • v.4 no.2
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    • pp.65-68
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    • 1999
  • The M-type barium ferrite ($BaFe_{12}O_{19}$) is well known magnetic material to be used as a permanent magnet due to its strong uniaxial anisotropy. The substitution of nonmagnetic $Ti^{+4}$ and magnetically weak $Co+^2ion for Fe^{+3}$ to its strong uniaxial anisotropy. The substitution of nonmagnetic $Ti^{+4}$ and magnetically weak $Co+^2ion for Fe^{+3}$ sublattices reduces the uniaxial anisotropy and those compounds open a new application field of noise suppressor at high frequencies. In this study, the magnetic and microwave absorbing properties are investigated in Ti-and Co-substituted barium ferrites ($BaFe_{12-2X} Ti_XCo_XO_{19}$). The saturated magnetization decreases linearly with the substitution of Ti and Co. The rapid drop in coercive force is observed with Ti and Co substitution upto x=1.2. The magnetic permeability spectrum shows the natural magnetic resonance in the specimens with small coercive force and large attenuation of microwave is predicted in those specimens at high frequencies (above 4 GHz).

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Effects of Metal Ions Mole Ratio, pH and Heat Treatment Condition on the Magnetic Properties and Formation of Co-precipitated M-type Barium Ferrite Powders (공침법으로 합성한 바륨 페라이트(BaM)의 형성과 자기적 성질에 미치는 금속이온 몰 비 및 pH와 열처리 조건의 영향)

  • Baek, In-Seung;Nam, In-Tak
    • Journal of the Korean Magnetics Society
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    • v.19 no.6
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    • pp.209-215
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    • 2009
  • M-type barium ferrite (BaFe12O19) powders were synthesized through the co-precipitation method. Starting material composition $Fe^{3+}:\;Ba^{2+}$ mole ratio was fixed as 8 and the relative amount of $Fe^{3+}$ and $Ba^{2+}$ was controlled. Structure and magnetic properties and powder morphology were investigated using XRD, SEM, VSM. Powder showing high coercivity and small magnetization was obtained at pH8 and $Fe_{3+}:\;Ba_{2+}$ of 12 : 1.5. Small magnetization value was originated from the existence of ${\alpha}-Fe_2O_3$. Single-phase Mtype barium ferrite were obtained regardless of the heat treatment condition and the amount of $Fe_{3+}\;and\;Ba_{2+}$ at pH$\approx$10. The largest value of magnetization (55.7 emu/g) under investigation were obtained when $Fe_{3+}:\;Ba_{2+}$ of 13.6 : 1.7 and furnace cooled powder in $O_2$. Particle size of powder was in the range of 50~200 nm.

Magnetic Properties and Structure of Co-precipitated Barium Ferrite (BaM) Powders (공침법으로 합성한 바륨 페라이트(BaM) 분말의 결정구조와 자기적 성질)

  • Baek, In-Seung;Nam, In-Tak
    • Journal of the Korean Magnetics Society
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    • v.20 no.4
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    • pp.134-142
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    • 2010
  • Barium ferrite ($BaFe_{12}O_{19}$) powders were synthesized by the co-precipitation method. $Fe^{3+}:Ba^{2+}$ mole ratio was fixed 8 and relative amount of $Fe^{3+}$ and $Ba^{2+}$ was controlled. The effects of the pH (= 8, 9, 10), calcination temperature and time on the morphology, structure and magnetic properties of the barium ferrite particles are characterized using XRD, FESEM, and VSM respectively. Coercivity and magnetization value of powders were changed with calcination temperature and time, relative amount of $Fe^{3+}$ and $Ba^{2+}$ and pH. Single-phase barium ferrite was obtained when pH value was 9 in the investigated range of $Fe^{3+}:Ba^{2+}$ relative amount and secondary phases were appeared at $Fe^{3+}:Ba^{2+}$ relative amount of 14.4 : 1.8. The largest value of magnetization (65.7 emu/g) was obtained when $Fe^{3+}:Ba^{2+}$ mole ratio was 12.8 : 1.6 and calcination temperature was $900^{\circ}C$ with air calcination atmosphere. The largest value of coercivity (5280 Oe) was obtained with $O_2$ calcination atmosphere.

Structural and Magnetic Properties of Z-type Barium Ferrite (Z-type 바리움 페라이트의 구조 및 자기적 성질)

  • Nam, In Tak
    • Journal of Industrial Technology
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    • v.28 no.A
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    • pp.119-123
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    • 2008
  • Structural and magnetic properties of $CO_{1-x}Zn_xZ$ ($Ba_3Co_{1-x}Zn_xFe_{24}O_{41}$) hexa-ferrite are studied using XRD, VSM and SEM, respectively. Powder was prepared from co-precipitation and firstly heat treated at $1350^{\circ}C$ for 6 hours in $O_2$ atmosphere. Second heat treatment was performed at 900, 1000, $1100^{\circ}C$ for 6 hours in air, respectively. Saturation magnetization value of first heat treated powder is acceptable and coercivity is high for applying to device. These result may be originated from incomplete formation reaction from M and Y phases to Z phase. Second heat treatment leads to small value of coercivity.

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