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Influence of change in cation distribution on the magnetic and catalytic properties via thermal annealing of spinel-type CoFe2O4
(2019-01-01)
Roongtao, Rachanusorn
;
Ruttanapun, Chesta
The influence of the change in cation distribution on the magnetic and catalytic properties by the thermal annealing process of CoFe<inf>2</inf>O<inf>4</inf> spinel was investigated. CoFe<inf>2</inf>O<inf>4</inf> was synthesized by solid-state reaction and annealed at 500 °C for 100 h. Samples of single-phase cubic spinel structure with and without annealing were characterized using X-ray diffraction. The thermal annealing caused a change in the cation distribution in the CoFe<inf>2</inf>O<inf>4</inf> structure, as confirmed by the X-ray absorption fine structure technique and least-squares fitting method. This result in the Co2+cation in the octahedral site increased with the Fe3+ cation decreasing, which effected the change in cation distribution. This was responsible for decreasing the saturation magnetization after annealing for the magnetic property, and increasing the degradation percentages of the solution after annealing for the catalytic property. This confirmed that thermal annealing on CoFe<inf>2</inf>O<inf>4</inf> was effective for cation distribution change and affected the magnetic and catalytic properties.
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Effect of Annealing Time on the Cation Distribution in Mn Doped CoFe2O4
(2016-02-19)
Roongtao, Rachanusorn
;
Vittayakorn, Naratip
;
Klysubun, Wantana
;
Vittayakorn, Wanwilai C.
In this work, the series of CoFe<inf>2</inf><inf>x</inf>Mn<inf>x</inf>O<inf>4</inf> powders were synthesized using the solid state method. The structure and lattice parameter of the samples were determined by the X-ray diffraction (XRD) and Rietveld refinement method. The morphology was confirmed without annealing and with annealing at 500°C for 4 and 100 h, with the samples examined by scanning electron microscopy (SEM). Then, the distribution of migrating cations was analyzed using X-ray absorption spectroscopy (XAS). Also, magnetic properties were examined by a vibrating sample magnetometer (VSM). It can be confirmed from the morphology that the average particle size before and after annealing remained unchanged, and ranged from 0.66 ± 0.20 m to 0.79 ± 0.26 m. Furthermore, the distribution of cations was no different after annealing Mn ions at 500°C for 100 h. However, the distribution of cations migrated to their site of preference after annealing Co and Fe ions in the structure. The result of migrations induced a saturated magnetization increase to 42.24 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
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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 Co2+, Fe3+ and Zn2+ ions. © 2013 Copyright Taylor and Francis Group, LLC.
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The influence of BMN addition on the phase formation, microstructure and dielectric property of BaTiO3 ceramic
(2013-01-01)
Vittayakorn, Wanwilai C.
;
Pulphol, Nattakarn
;
Roongtao, Rachanusorn
;
Muanghlua, Rangson
;
Vittayakorn, Naratip
Solid solutions of the (1-x)BT-xBMN system were prepared successfully by the solid state reaction method followed by normal sintering in air. The phase formation, microstructure and dielectric property of BT-BMN ceramics were investigated as a function of compositions. XRD results showed a single perovskite phase for all compositions. Cubic-tetragonal transformation was found after adding BMN into the system. SEM micrographs revealed two very different grain sizes in the ceramics, with compositions of x = 0.02, 0.03, 0.04 and 0.05. Fine grains indicated a cubic structure, whereas large ones indicated a tetragonal structure. Regarding the dielectric property, Curie temperature decreased with increasing BMN content, whereas the er value increased until the BMN content reached 3 mol% before dropping to a lower value. Copyright © 2013 Taylor & Francis Group, LLC.

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