• Title/Summary/Keyword: Ba Ferrite

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The Preparation and Magnetic Properties of Single-Crystallite of Ba-Ferrite from Ba-Sol Coated $\delta$-FeOOH (Ba-Sol을 도포한 $\delta$-FeOOH로부터 Ba-Ferrite 단결정 미리자의 제조와 그 자기적 특성)

  • 박영도;이훈하;이재형;오영우;김태옥
    • Journal of the Korean Ceramic Society
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    • v.32 no.12
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    • pp.1383-1391
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    • 1995
  • Hexagonal $\delta$-FeOOH was coated with Ba-Sol, which was produced by hydrolizing Ba(OC2H5)2, Ba-Sol coated $\delta$-FeOOH spread on a stainless plate, dried at 8$0^{\circ}C$ and then heat-treated. In this way, Ba-ferrite fine particles were produced. although there was a difference in a degree of hydrolysis of Ba(OC2H5)2, crystalline phase of Ba-ferrite appeared around 617$^{\circ}C$, and Ba-ferrite single phase was obtained after heat treatment at 80$0^{\circ}C$ for 2 hr. When Ba-ferrite was made from Ba-Sol coated $\delta$-FeOOH, $\delta$-FeOOH was thermally decomposed to $\alpha$-Fe2O3 at $700^{\circ}C$, producing a porous structure which was observed by TEM photographs. But the porous structure was not observed at 80$0^{\circ}C$. Ba-ferrite, heat-treated at 80$0^{\circ}C$ for 2 hr, had mean particle size of 1000$\AA$, lattice parameter of a0=5.889243 $\AA$ and c0=23.214502 $\AA$, a saturation magnetization ($\sigma$8) of 45.3 emu/g and a coercive force (Hc) of 5200Oe.

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The Effect of Hydrogen Reduction Treatment on Properties of Ba-ferrite (환원처리가 Ba-ferrite의 물성에 미치는 영향)

  • 홍양기;정홍식;김현준
    • Journal of the Korean Magnetics Society
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    • v.7 no.1
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    • pp.25-30
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    • 1997
  • Physical and magnetic behaviors of reduced Co-Zn-Ti-Sn substituted Ba-ferrite particles with hydrogen are different from those of reduced-pure Ba-ferrite particles. The coercivity of substituted Ba-feffite particles shows a peaking effect with the reduction temperature ranging from 250 to 520 $^{\circ}C$, while the coercivity of pure Ba-ferrite decreases monotonically. The reduction process of substituted Ba-ferrite has been found to be devided into three steps. At the first and second steps, the magneto-plumbite structure maintained. When the reduced-substituted Ba-ferrite particles are reoxidized, the coercivity is reversible at the first step but irreversible at the second step. During the third step of reduction process above 410 $^{\circ}C$. The magneto plumbite structure was collapsed with formation of $\alpha$-Fe and $BaFeO_{3-x}$ phases and consequently the coercivity distribution is broaden and the coercivity irreversible. The coercivity and saturation magnetization decreases and increases up to 130 emu/g respectively. In this study, it is found that the substituted elements prevent the magneto-plumbite structure from collapse during the reduction process and furthermore migrate from the magnetic sites of $2a+4f_{IV}$, 2b, and 12k to $4f_{VI}$ and 12k'. An increase in the coercivity before the collapse of magneto-plumbite structure is attributed to the migration of cations in hexagonal Ba-ferrite structure.

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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.

Effect of Processing Factors on the Properties of Melt-blown PP/Ba-ferrite Composite Fabrics (Melt-blown 방사에 의한 PP/Ba-ferrite 복합 부직포 제조시의 공정인자가 부직포의 특성에 미치는 영향)

  • Han, Jong-Hun;Lee, Dong-Jin;Lim, Hyung Mi;Lee, Seung-Ho;Oh, Sung Geoun
    • Applied Chemistry for Engineering
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    • v.17 no.3
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    • pp.267-273
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    • 2006
  • We have prepared PP/Ba-ferrite composite fabrics by a melt-blown spinning method and investigated the relationship between the properties of PP/Ba-ferrite composite fabrics and melt-blown processing factors. A PP composite containing Ba-ferrite as a magnetic particulate filler was prepared in the form of pellet from PP resin and Ba-ferrite powder by melt compounding using a single extruder. Screw turning force (rpm), DCD (die-to-collector distance), and Ba-ferrite content were changed. We measured diameters of fiber, mechanical, thermal, and magnetic properties for the composited PP fabrics. The elongation was increased and a fiber diameter and tensile strength were decreased as the spinning distance increased or screw turning force decreased. The crystallinity was increased with increasing spinning distance according to XRD. It was assumed that the orientation of crystalline domain in the neat PP without ferrite was increased by drawing in mechanical direction, however, the orientation in the PP composite was decreased according to XRD analysis. We measured a magnetic property of PP nonwoven fabric containing Ba-ferrite powder. A coercive force, maximum magnetization, and residual magnetization are reduced with the spinning distance. According to the result of TGA measurement, the heat resistance was increased with the Ba-ferrite powder content and with decreasing the spinning distance.

The Preparation and Magnetic Properties in Ba-ferrite Film on the A12O3 Substrate (A12O3을 하지층으로 하는 Ba-ferrite 박막의 제조 및 자기적 특성에 관한 연구)

  • Sur, Jung-Chul;Park, Chul-Jin;Choi, Jung-Wan
    • Journal of the Korean Magnetics Society
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    • v.15 no.2
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    • pp.125-129
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    • 2005
  • Ba-Ferrite thin films were prepared on $A1_2O_3$ substrate by a pulsed laser deposition system and characterized by SEM, $M\ddot{o}$ssbauer spectroscopy and VSM. The appropriate conditions of pulsation in Ba-ferrite was the oxygen pressure of 0.1 Torr at a substrate temperature of $400^{\circ}C$ and the thickness was variable with the deposition time. Ba-ferrite crystals had the forms of hexagonal plate in the 5 minute deposited film and the needle grains coexisted with the increasing film thickness. $M\ddot{o}ssbauer$ spectroscopy assured that the direction of atomic spin in Fe ion tends to normal to the substrate in the hexagonal plate. The VSM curves have the two types hysteresis of hexagonal and needle phase.

Development of Composite Ba Ferrite EM Wave Absorbers for GHz Frequency (GHz 대역용 복합형 Ba 페라이트 전파흡수체의 개발)

  • 문상현;신승재;송재만;김동일;김기만
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.12
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    • pp.1329-1334
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    • 2003
  • We prepared EM wave absorbers by using recycled Ba ferrite far GHz frequency, and investigated the effects of carbon additions and preparation temperatures on their EM wave absorption properties. We clarified that it is very important to consider carbon amounts in Ba ferrite and preparation temperature for Ba ferrite EM wave absorbers with high quality.

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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Development of The Magnetic Abrasive Using Barium Ferrite (Ba-Ferrite를 이용한 자기 연마재 개발)

  • 김희남;송승기;정윤중;윤여권;김희원;조상원;심재환
    • Journal of the Korean Society of Safety
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    • v.18 no.2
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    • pp.46-49
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    • 2003
  • The magnetic polishing is the useful method to finish some machinery fabrications by using magnetic power. This method is one of the precision techniques and has m aim for clean technology in the transportation of the pure gas in the clean pipes. The magnetic abrasive polishing method is not so common in the field of machine that it is not known to widely. There are rarely researcher in this field because of non-effectiveness of magnetic abrasive. Therefore, in this paper we deals with the development of the magnetic abrasive with the use of Ba-Ferrite. In this development, abrasive grain WA has been made by using the min bond fabricated at low temperature. And magnetic abrasive powder was fabricated from the Ba-Ferrite which was crushed into 200 mesh. The XRD analysis result shows that only WA abrasive and Ba-Ferrite crystal peaks were detected, explaining that resin bond was not any more to contribute chemical reaction. From SEM analysis, we found that WA abrasive and Ba-Ferrite were strongly bonding with each other.

Formation Process of Barium Ferrite Crystallites in Molten Salts and its Magnetic properties (용융염내에서의 Ba-ferrite 결정의 생성과정 및 그 자기적 특성)

  • 정지형;김창곤;윤석영;신학기;김태옥
    • Journal of the Korean Ceramic Society
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    • v.38 no.11
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    • pp.1015-1022
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    • 2001
  • In this study, formation process of Ba-ferrite by using molten salt synthesis and its magnetic properties were investigated. Among starting materials, BaC $O_3$was only soluble in the molten salts, but other starting material such as $\delta$-FeOOH or F $e_2$ $O_3$was not soluble even at 105$0^{\circ}C$. It implies that the dissolved $Ba^{2+}$ diffused on surfaces of F $e_2$ $O_3$(or $\delta$-FeOOH), therefore, Ba-ferrtites were formed through surface reaction. However, the magnetic properties of Ba-ferrite prepared by two starting materials (F $e_2$ $O_3$and $\delta$-FeOOH) were not different. On the other hand, compared $\delta$-FeOOH with F $e_2$ $O_3$m, morphologies and dispersibility of Ba-ferrites prepared by using $\delta$-FeOOH were good and Ba-ferrites were obtaioned at lower temperature.

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Effects of Ball-Milling Time on Formation and Magnetic Properties of Ba-Ferrite (Ba-Ferrite의 생성 및 자기적 성질에 미치는 분쇄시간의 영향)

  • Hyo Duk Nam;Sang Hee Cho
    • Journal of the Korean Chemical Society
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    • v.27 no.3
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    • pp.224-232
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    • 1983
  • The effects of ball-milling time on solid state reactions in the system $BaCO_3-Fe_2O_3$ and the magnetic properties of Ba-ferrite 4(BaFe_{12}O_{19})$ have been studied. $BaCO_3-Fe_2O_3 $mixtures were prepared by ball-milling for varying lengths of time; 5, 15, 30, 80 and 200 hours. Techniques employed were thermogravimetry, X-ray diffraction analysis, scanning electron microscopy and B-H curve tracer. It is shown that the aggregation states and superparamagnetic size fractions obtained by increasing ball-milling time have remarkable effects on solid state reactions and magnetic properties of Ba-ferrite.

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