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Access type: UnknownSubject: search.filters.subject.Cobalt ferrite

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    Modifying Barium Hexaferrite Magnets by Adding SoleGel Synthesized Cobalt Ferrite Phase
    (2023-01-01)
    Charoensuk, Thanida
    ;
    Thongsamrit, Wannisa
    ;
    Hunyek, Anuchit
    ;
    Chokprasombat, Komkrich
    ;
    Jantaratana, Pongsakorn
    Combining various types of ferrites brings about magnetic properties desirable for different applications. This study aims to modify barium hexaferrite (BaFe<inf>12</inf>O<inf>19</inf>) by physically mixing it with cobalt ferrite (CoFe<inf>2</inf>O<inf>4</inf>). BaFe<inf>12</inf>O<inf>19</inf>/CoFe<inf>2</inf>O<inf>4</inf> magnets were produced by ball-milling and pressing solegel-derived ferrite powders. The ferrite composites showed variations in magnetic properties from BaFe<inf>12</inf>O<inf>19</inf> magnets with a saturation magnetization of 69.46 emu/g and a maximum energy product of 0.4529 MGOe. For the BaFe<inf>12</inf>O<inf>19</inf>:CoFe<inf>2</inf>O<inf>4</inf> weight ratio of 4:1, both saturation and remanent magnetizations were increased due to the addition of CoFe<inf>2</inf>O<inf>4</inf> with high magnetizations. However, the magnetizations were reduced when the BaFe<inf>12</inf>O<inf>19</inf>:CoFe<inf>2</inf>O<inf>4</inf> ratio was reduced to 2:1. On the other hand, the coercivity was monotonously decreased with increasing CoFe<inf>2</inf>O<inf>4</inf>. Interestingly, the maximum energy product in this study was linearly decreased with the bulk density of the magnets from 3.59 to 3.15 g/cm<sup>3</sup>. It is concluded that magnetic properties could be modified from a facile physical mixing of ferrites.
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    Synthesis of nanocrystalline cobalt ferrite by the sonochemical method in highly basic aqueous solution
    (2017-01-01)
    Pasupong, Patchara
    ;
    Choojun, Kittisak
    ;
    Vittayakorn, Naratip
    ;
    Seeharaj, Panpailin
    This study reported the preparation of nanocrystalline CoFe2O4 in single step by the sonochemical method in highly basic aqueous solution without requiring of high temperature calcination process. To prepare nanocrystalline CoFe2O4, the mixed solution of the required molar ratio of cobalt nitrate hexahydrate (Co(NO<inf>3</inf>).6H2O) and ferric nitrate nonahydrate (Fe(NO<inf>3</inf>).9H2O) was precipitated in high concentration of sodium hydroxide medium solution (NaOH) under high intensity ultrasonic irradiation (20 kHz, 150 W/cm2). The effect of NaOH concentration (5, 10, 15 and 20 M) on phase formation, microstructure and magnetic property of CoFe2O4 was investigated. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA) results showed that the as-prepared powders were single phase CoFe2O4 with cubic spinel structure. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) study showed that nanocrystalline CoFe2O4 had monosized distorted spherical morphology and an agglomeration of the nanocrystalline CoFe2O4 into nanoparticles was observed when increasing the NaOH concentration. The nanocrystalline CoFe2O4 exhibited superparamagnetic property and the saturation magnetization (Ms) obtained from vibrating sample magnetometry (VSM) was found to correlate with the crystallite size and varied from 39-45 emu/g.
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    Influence of Mn doping on the magnetic properties of CoFe2O 4
    (2014-01-03)
    Roongtao, Rachanusorn
    ;
    Baitahe, Rattanai
    ;
    Vittayakorn, Naratip
    ;
    Seeharaj, Panpailin
    ;
    Vittayakorn, Wanwilai C.
    A series of CoFe<inf>2-x</inf>MnxO<inf>4</inf> ceramics were synthesized successfully by conventional solid state reaction. The X-ray diffraction analysis proved that all samples were found to have a cubic spinel structure. Diffractograms were used for Rietveld refinement to determine lattice parameters, of which lattice parameter increased with increasing Mn concentration. The microstructure of the samples was studied using scanning electron microscopy. The vibrating sample magnetometer measurements showed that the highest saturated magnetization of 118.11 emu/g and coercivity of 46.89 Oe were observed in CoFe<inf>1.85</inf>Mn<inf>0.15</inf>O<inf>4</inf> ceramic. Furthermore, X-ray absorption spectra of the samples were recorded to determine the Co, Fe and Mn valence states and their preferentially sites of the spinel structure. © 2014 Taylor and Francis Group, LLC.
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    Structural and magnetic properties of Zn doped CoFe2O 4
    (2013-12-01)
    Roongtao, Rachanusorn
    ;
    Baitahe, Rattanai
    ;
    Vittayakorn, Naratip
    ;
    Klysubun, Wantana
    ;
    Vittayakorn, Wanwilai C.
    Zinc doped cobalt ferrite powders were prepared by the solid state reaction method. The effect of zinc substitution on structure, morphology and magnetic properties was investigated. The X-ray analysis confirmed existence of the single phase cubic spinel structure, while Rietveld refinement data showed increasing of lattice parameters with zinc content. In addition, saturated magnetization increased with increasing zinc concentration and it was contained at maximum in CoFe<inf>1.9</inf>Zn0.<inf>1</inf>O<inf>4</inf> powders. However, the value of coercivity was decreased with zinc doped content. Furthermore, the oxidative states were characterized by X-ray absorption spectroscopy. The results confirm that the structure contained Co<sup>2+</sup>, Fe<sup>3+</sup> and Zn<sup>2+</sup> ions. © 2013 Copyright Taylor and Francis Group, LLC.