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Loading effect of sol-gel derived barium hexaferrite on magnetic polymer composites
(2021-03-01)
Charoensuk, Thanida
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Thongsamrit, Wannisa
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Ruttanapun, Chesta
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Jantaratana, Pongsakorn
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Sirisathitkul, Chitnarong
Solution–processing methods were investigated as viable alternatives to produce the polymer-bonded barium hexaferrite (BaM). BaM powders were first synthesized by using the sol-gel auto-combustion method. While the ignition period in two synthesis batches varied, the morphology of hexagonal microplates and nanorods, as well as magnetic properties, were reproduced. To prepare magnetic polymer composites, these BaM powders were then incorporated into the acrylonitrile-butadiene-styrene (ABS) matrix with a weight ratio of 80:20, 70:30, and 60:40 by using the solution casting method. Magnetizations were linearly decreased with a reduction in ferrite loading. Compared to the BaM loose powders and pressed pellet, both remanent and saturation magnetizations were lower and gave rise to comparable values of the squareness. The squareness around 0.5 of BaM samples and their composites revealed the isotropic alignment. Interestingly, the coercivity was significantly increased from 1727–1776 Oe in loose BaM powders to 1874–2052 Oe for the BaM-ABS composites. These composites have potential to be implemented in the additive manufacturing of rare-earth-free magnets.
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Effect of sr substitution on structural, ferroelectric and magnetic properties of la1-xsrxfeo3 perovskite oxides
(2020-01-01)
Kaewpanha, Malinee
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Nunocha, Pornnipa
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Bongkarn, Theerachai
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Eiad-Ua, Apiluck
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Suriwong, Tawat
Effect of Sr substitution on structural, magnetic and electrical properties of LaFeO<inf>3</inf> perovskite oxides has been studied. Using the selected Sr doping content (x) from 0.0 to 1.0, perovskite La<inf>1-x</inf>Sr<inf>x</inf>FeO<inf>3</inf> nanopowder was synthesized by sol-gel auto-combustion method, followed by calcination at 900 °C for 2 h. The synthesized powder was pressed into disks at room temperature and then the disk samples were sintered at 1200 °C for 12 h to obtain a single-phase compound formation and uniaxial compaction. The influence of Sr doping on the phase formation, morphology, ferroelectric and magnetic properties was investigated. The phase formation of the sample changes from orthorhombic at low Sr doping through rhombohedral to cubic for Sr-rich sample as the stoichiometry approached SrFeO<inf>3</inf>. The grains of La<inf>1-x</inf>Sr<inf>x</inf>FeO<inf>3</inf> ceramics revealed an irregular polyhedron shape. SEM-EDS mapping analysis also exhibited the uniform distribution of all elements. The direct energy gap (E<inf>g</inf>) was found to decrease with increasing amounts of Sr doping. Moreover, the La<inf>0.6</inf>Sr<inf>0.4</inf>FeO<inf>3</inf> ceramic exhibited ferromagnetic behavior with saturated magnetization (M<inf>s</inf>) of 0.305 emu/g at room temperature.
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Synchrotron X-ray absorption spectroscopy study of disordered cation distribution of nanosized zinc ferrite powders
(2016-01-01)
Tangcharoen, Thanit
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Kongmark, Chanapa
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Klysubun, Wantana
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Pecharapa, Wisanu
The zinc ferrite (ZnFe<inf>2</inf>O<inf>4</inf>) powders of various nanoparticle sizes were synthesised at different milling times (0 to 24 h) of the as-combusted powders. The non-equilibrium site occupancy of zinc (Zn2+) and ferric (Fe3+) ions was investigated through Zn and Fe K-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra. The XRD and SEM strongly confirm the particle size of these ferrites decreasing with the increasing milling time. Compared with the bulk specimen of zinc ferrite, both XANES and EXAFS spectra of zinc ferrite powders clearly exhibit the large translocation of Zn2+ ions from the tetrahedral (A) sites to the octahedral (B) sites and the opposite translocation of some of Fe3+ ions without affecting the long-range structural order. Moreover, the curve-fitting analysis of Zn and Fe K-edge EXAFS spectra indicates that the degree of inversion increases as the particle size decreases resulting in significant differences in the magnetic behaviours.
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Characterization and enhanced photocatalytic performance of nanocrystalline Ni-substituted Zn ferrites synthesized by DEA-assisted sol-gel auto-combustion method
(2013-06-01)
Tangcharoen, Thanit
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Ruangphanit, Anucha
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Klysubun, Wantana
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Pecharapa, Wisanu
Nanocrystalline Ni-substituted Zn ferrites with compositions of Ni <inf>x</inf>Zn<inf>1-x</inf>Fe<inf>2</inf>O<inf>4</inf> (x = 0-1.0) were synthesized by sol-gel auto-combustion method using metal nitrate as the reactants. Diethanolamine was selected as the fuel instead of conventional fuels such as urea, citric acid, tartaric acid or glycine. Characterization of after-calcined ferrite samples were conducted in terms of crystal structure, molecular vibrations, morphology and magnetic properties through X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope and vibrating sample magnetometer analysis, respectively. The photocatalytic activities of these ferrites were studied in term of degradation of Rhodamine B under daylight-irradiation. The corresponding results indicate that nickel loading content has significant effect on physical, magnetic, optical and photocatalytic properties of the ferrite. Comparing to the undoped Zn ferrite, Ni<inf>0.6</inf>Zn<inf>0.4</inf>Fe<inf>2</inf>O<inf>4</inf> shows the enhancement in photocatalytic activity accompanying the degradation of Rhodamine B aqueous solution up to 77 % within 4 h. The result suggests the feasibility of this material as potential sunlight-activated photocatalyst in wastewater treatment and environment cleaning applications. © 2013 Springer Science+Business Media New York.

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