• Title/Summary/Keyword: $BaFe_{12}O_{19}$

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Fabrication and Magnetic Properties of Mg and BaFe12O19 Ferromagnetic Composite Powders by Mechanical Alloying (기계적합금화법에 의한 Mg-BaFe12O19 계 강자성 복합분말의 제조 및 자기특성)

  • Lee, Chung-Hyo
    • Korean Journal of Materials Research
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    • v.31 no.2
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    • pp.61-67
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    • 2021
  • Fabrication of a ferromagnetic composite powder for the magnesium and BaFe12O19 system by mechanical alloying (MA) is investigated at room temperature. Mixtures of Mg and BaFe12O19 powders with a weight ratio of Mg:BaFe12O19 = 4:1, 3:2, 2:3 and 1:4 are used. Optimal MA conditions to obtain a ferromagnetic composite with fine microstructure are investigated by X-ray diffraction, differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM) measurement. It is found that Mg-BaFe12O19 composite powders in which BaFe12O19 is dispersed in Mg matrix are successfully produced by MA of BaFe12O19 with Mg for 80 min. for all compositions. Magnetization of Mg-BaFe12O19 composite powders gradually increases with increasing the amounts of BaFe12O19, whereas coercive force of MA powders gradually decreases due to the refinement of BaFe12O19 powders with MA time for all compositions. However, it can be seen that the coercivity of Mg-BaFe12O19 MA composite powders with a weight ratio of Mg:BaFe12O19=4:1 and 3:2 for MA 80 min. are still high, with values of 1260 Oe and 1320 Oe compared to that of Mg:BaFe12O19=1:4. This clearly suggests that the refinement of BaFe12O19 powders during MA process for Mg:BaFe12O19=4:1 and 3:2 tends to be suppressed due to ductile Mg powders.

Synthesis and magnetic properties of copper and Ba-ferrite ferromagnetic composites by mechanical alloying (기계적합금화법에 의한 Cu-Ba ferrite 강자성 복합재료의 합성 및 자기적 성질)

  • Lee, Chung-Hyo
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.28 no.1
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    • pp.21-27
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    • 2018
  • Synthesis of ferromagnetic composite materials for the $Cu-BaFe_{12}O_{19}$ system by mechanical alloying (MA) has been investigated at room temperature. A mixture of copper and barium ferrite with a weight ratio of $Cu:BaFe_{12}O_{19}=4:1$, 3 : 2, 2 : 3 and 1 : 4 was used. It is found that $Cu-BaFe_{12}O_{19}$ composite powders in which $BaFe_{12}O_{19}$ is dispersed in copper matrix are successfully produced by mechanical alloying of $BaFe_{12}O_{19}$ with Cu for 80 min. in all composition. The change in X-ray diffraction patterns and magnetic properties reflects the details for the formation of ferromagnetic metal matrix composite of pure Cu and $BaFe_{12}O_{19}$ during mechanical alloying. Magnetization of $Cu-BaFe_{12}O_{19}$ composite powders gradually increases with increasing the amounts of barium ferrite, whereas coercive force of MA powders gradually decreases due to the refinement of barium ferrite powders with ball milling. However, it can be seen that the coercivity of $Cu-BaFe_{12}O_{19}$ MA composite powders with a weight ratio of $Cu:BaFe_{12}O_{19}=4:1$ and 3 : 2 ball-milled for 80 min. is still high value of 1400 Oe and 1450 Oe, respectively suggesting that the refinement of barium ferrite powders during ball milling process tend to be suppressed due to the ductile copper.

Growth of Oriented Thick Films of BaFe12O19 by Reactive Diffusion

  • Fisher, John G.;Vu, Hung;Farooq, Muhammad Umer
    • Journal of Magnetics
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    • v.19 no.4
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    • pp.333-339
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    • 2014
  • Single crystal growth of $BaFe_{12}O_{19}$ by the solid state crystal growth method was attempted. Seed crystals of ${\alpha}-Fe_2O_3$ were pressed into pellets of $BaFe_{12}O_{19}$ + 2 wt% $BaCO_3$ and heat-treated at temperatures between $1150^{\circ}C$ and $1250^{\circ}C$ for up to 100 hours. Instead of single crystal growth taking place on the seed crystal, BaO diffused into the seed crystal and reacted with it to form a polycrystalline reaction layer of $BaFe_{12}O_{19}$. The microstructure, chemical composition and structure of the reaction layer were studied using scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), x-ray Diffraction (XRD) and micro-Raman scattering and confirmed to be that of $BaFe_{12}O_{19}$. XRD showed that the reaction layer shows a strong degree of orientation in the (h00)/(hk0) planes in the sample sintered at $1200^{\circ}C$. $BaFe_{12}O_{19}$ layers with a degree of orientation in the (hk0) planes could also be grown by heat-treating an ${\alpha}-Fe_2O_3$ seed crystal buried in $BaCO_3$ powder.

A study on Magnetic Properties of BaFe12O19 Fabricated by Ultrasonic Spray-pyrolysis Process Using Self-Assembly Method (자기 조립 전구체를 이용한 초음파 분무 열분해 공정으로 제조한 BaFe12O19의 자기적 특성에 대한 연구)

  • Choi, Moon-Hee;Yu, Ji-Hun;Kim, Dong-Hwan;Chung, Kook-Chae;Kim, Yang-Do
    • Journal of Powder Materials
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    • v.17 no.4
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    • pp.263-269
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    • 2010
  • Hexagonal barium ferrite ($BaFe_{12}O_{19}$) nano-particles have been successfully fabricated by spraypylorysis process. $BaFe_{12}O_{19}$ precursor solutions were synthesized by self-assembly method. Diethyleneamine (DEA) surfactant was used to fabricate the micelle structure of Ba-DEA complex under various DEA concentrations. $BaFe_{12}O_{19}$ powders were synthesized with addition of Fe ions to Ba-DEA complex and then fabricated $BaFe_{12}O_{19}$ powders by spray-pyrolysis process at the temperature range of $800{\sim}1000^{\circ}C$. The molar ratio of Ba/DEA and heat-treatment temperatures significantly affected the magnetic properties and morphology of $BaFe_{12}O_{19}$ powders. $BaFe_{12}O_{19}$ powders synthesized with Ba/DEA molar ratio of 1 and heat-treated at $900^{\circ}C$ showed the coercive forces (iHc) of 4.2 kOe with average crystal size of about 100 nm.

Magnetic Properties of Hard/Soft Nanocomposite Ferrite Synthesized by Self-Combustion Precursors (자전 연소 전구체로 합성한 나노 크기 경/연 복합페라이트의 자기 특성)

  • Oh, Young Woo;Ahn, Jong Gyeon
    • Journal of the Microelectronics and Packaging Society
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    • v.22 no.3
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    • pp.45-50
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    • 2015
  • The goal of this research is the create novel magnets with no rare-earth contents, with larger energy product by comparison with currently used ferrites. For this purpose we developed nano-sized hard-type/soft-type composite ferrite in which high remanent magnetization (Mr) and high coercivity (Hc). Nano-sized Ba-ferrite, Ni-Zn ferrite and $BaFe_{12}O_{19}/Ni_{0.5}Zn_{0.5}Fe_2O_4$ composite ferrites were prepared by sol-gel combustion method by use of glicine-nitrate and citric acid. Nanocomposite ferrites were calcined at temperature range $700-900^{\circ}C$ for 1h. According to the X-ray diffraction patterns and FT-IR spectra, single phase of NiZn-ferrite and Ba-ferrite were detected and hard/soft nanocomposite ferrite was indicated to the coexistence of the magnetoplumbite-structural $BaFe_{12}O_{19}$ and spinel-structural $Ni_{0.5}Zn_{0.5}Fe_2O_4$ that agreed with the standard JCPDS 10-0325 data. The particle size of nanocomposite turn out to be less than 120 nm. The nanocomposite ferrite shows a single-phase magnetization behavior, implying that the hard magnetic phase and soft magnetic phase were well exchange-coupled. The specific saturation magnetization ($M_s$) of the nanocomposite ferrite is located between hard ($BaFe_{12}O_{19}$) and soft ferrite($Ni_{0.5}Zn_{0.5}Fe_2O_4$). The remanence (Mr) of nanocomposite ferrite is much higher than that of the individual $BaFe_{12}O_{19}$ and $Ni_{0.5}Zn_{0.5}Fe_2O_4$ ferrite, and $(BH)_{max}$ is increased slightly.

The Influence of Ferromagnetic $BaFe_{12}O_{19}$ Layer for Low-Field Tunnel-Type Magnetoresistance on $La_{2/3}Sr_{1/3}MnO_3/BaFe_{12}O_{19}/SiO_2/Si(001)$ Granular-Type Multilayer Thin Films ($La_{2/3}Sr_{1/3}MnO_3/BaFe_{12}O_{19}/SiO_2/Si(001)$ 입상형 다층박막 구조에서 강자성 $BaFe_{12}O_{19}$ 중간층이 저 자장 터널형 자기저항 특성에 미치는 영향)

  • 심인보;안성용;이희민;유홍주;김철성;최세영
    • Proceedings of the Korean Magnestics Society Conference
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    • 2001.10a
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    • pp.48-49
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    • 2001
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Preparation of C-plane oriented BaFe12O19 film by electrospray deposition of colloidal precursor particles (정전분무 장치를 이용한 C축 일방향 바륨페라이트(BaFe12O19) 박막형성)

  • Lee, Hye Moon;Kim, Yong Jin
    • Particle and aerosol research
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    • v.6 no.1
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    • pp.21-27
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    • 2010
  • New process consisting of electrospray and epitaxial crystal growth processes was applied to the preparation of c-plane oriented barium ferrite ($BaFe_{12}O_{19}$) thin film for high density magnetic recording media. Sodium citrate aided process was proper to preparation of amorphous $BaFe_{12}O_{19}$ nanoparticles with geometric mean diameter of 3 nm and geometric standard deviation of 1.1. The electrospray was applicable to the prepare of amorphous $BaFe_{12}O_{19}$ thin film on a substrate, and the film thickness could be controlled by adjusting the electrospray deposition time. The c-plane oriented $BaFe_{12}O_{19}$ thin film was successfully prepared by 3 step annealing process of the $BaFe_{12}O_{19}$ amorphous film on a sapphire($Al_2O_3$) substrate; annealing at $350^{\circ}C$ for 30 min, annealing at $500^{\circ}C$ for 30 min, and annealing at $700^{\circ}C$ for 60 min.

$Fe_2O_3$ Aggregation and Sintering of Ba-Ferrite ($Fe_2O_3$ 응집상태와 Ba-Ferrite의 소결성)

  • Hyo-Duk Nam;Sang-Hee Cho
    • Journal of the Korean Chemical Society
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    • v.25 no.5
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    • pp.318-324
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    • 1981
  • The effects of$ Fe_2O_3$ aggregation on the sintering of Ba-ferrite (BaFe$_{12}O_{19}$) were studied. $BaCO_3-Fe_2O_3$ mixtures were prepared by partial precipitation mixing and ball-mill mixing method using two different $Fe_2O_3 $powders. Techniques employed were TG, XRD and SEM. X-ray diffraction analysis showed that the over all reaction basically consists of the two consecutive reaction; $BaCO_3 + 6Fe_2O_3\;{\longrightarrow}\;BaFe_2O_3 + 5Fe_2O_3 + CO_2{\uparrow}\;BaFe_2O_4 + 5Fe_2O_3 \;{\longrightarrow}\;BaFe_{12}O_{19}$ It is also shown that the aggregation state of $Fe_2O_3$ raw materials, as well as the mixing method, has a remarkable effect on solid state reaction between $BaCO_3\;and\;Fe_2O_3$.

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Characteristics of BaFe12O19 Particles Extracted from Amorphous Ba-Ferrite (비정질 Ba-Ferrite로부터 추출한 BaFe12O19 입자의 특성)

  • 김태옥;오영우;박효열;강원호
    • Journal of the Korean Ceramic Society
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    • v.24 no.6
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    • pp.553-560
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    • 1987
  • Amorphous ferrites with composition B2O3-mBaO-nFe2O3 were prepared by an ultra rapidquenching technique. X-ray patterns and SEM reveal the products to be amrophous at room temperature. BaFe12O19 fine particles extracted from amorphous Ba-ferrites which additived Al2O3, SiO2, TiO2 and CoO have narrow size distribution, average 0.2$\mu\textrm{m}$, and coercive force, average 1400 Oe, increased with increasing TiO2 amounts. The obtained BeFe12O19 fine particles would be appreciated as perpendicular magnetic recording media.

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The Preparation and Mossbauer Study of M-type Barrium Ferrite using Salt-Catalysis Method (소금-촉매에 의한 M형 Barrium Ferrite의 제조 및 Mossbauer 분광학적 연구)

  • 이충섭;권동욱;권해웅
    • Journal of the Korean Magnetics Society
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    • v.9 no.1
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    • pp.17-22
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    • 1999
  • Hexagonal M-type barium ferrite $BaFe_{12}O_{19}$ was prepared by a direct solid state reaction between $BaCO_3$ and ${\Alpha}-Fe_2O_3$ powders at temperatures ranging from 800 to 1000 $^{\circ}C$ in a nitrogen or air environment. The effects of NaCl on phase transformation of mixture of $BaCO_3$ and ${\Alpha}-Fe_2O_3$ to $BaFe_{12}O_{19}$ were studied using X-ray diffraction and M$\"{o}$ssbauer spectroscopy. Regardless of the environment for heat treatment or the added NaCl, two phases, BaFe and ${\Alpha}-Fe_2O_3$, coexist for samples heat treated at 800 $^{\circ}C$, but a single phase was observed from samples heat treated at 100$0^{\circ}C$ in both air and nitrogen environments. It was found that the addition of NaCl reduced the amount of $a-Fe_2O_3$ phase.hase.

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