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Author: search.filters.author.Ruangphanit, AnuchaSubject: search.filters.subject.Ferrites

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    A comparison of cation distribution and valence state in spinel crystal structure of zinc and nickel ferrites using the synchrotron X-ray absorption spectroscopy (XAS) analysis
    (2014-07-24)
    Tangcharoen, Thanit
    ;
    Klysubun, Wantana
    ;
    Ruangphanit, Anucha
    ;
    Pecharapa, Wisanu
    In this work, the physical structure, magnetism and local structure of zinc and nickel ferrites (ZnFe<inf>2</inf>O<inf>4</inf> and NiFe<inf>2</inf>O <inf>4</inf>) synthesized by typical sol-gel combustion method, were investigated by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). The formation of the single phase cubic spinel crystal structure and the different values of crystallite size (D), interplanar distance (d) and lattice constant (a) for all ferrite samples were evaluated by the XRD data. The VSM measurement provides the characteristic magnetic hysteresis loop (M-H) for each sample which was found to be significantly different from each other. The chemical shifts in Zn, Ni and Fe K-edges XANES spectra indicate the existence of Zn<sup>2+</sup>, Ni<sup>2+</sup> and Fe<sup>3+</sup> ions in these ferrites. The EXAFS spectra analyses applied to track Zn, Ni and Fe cation distribution indicate the distinct character of spinel crystal structure of both ferrites. The results exhibit that zinc ferrite is a normal spinel, while the nickel ferrite is an inverse spinel. Moreover, these EXAFS spectra analyses reveal that the distances between metal ion (Zn<sup>2+</sup> or Ni<sup>2+</sup>) to central oxygen ion and to Fe<sup>3+</sup> ions in the opposite lattice site for each ferrite sample are unequal which highly affect its magnetism. The overall simulated results are one of the important evidence encouraging the explanation on the paramagnetism for ZnFe<inf>2</inf>O<inf>4</inf> and the ferrimagnetism for NiFe<inf>2</inf>O<inf>4</inf>. © 2014 Taylor & Francis Group, LLC.
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    Sol-gel combustion synthesis and characterizations of nanocrystalline Zinc, Nickel and Nickel-Zinc ferrites
    (2013-10-29)
    Tangcharoen, Thanit
    ;
    Ruangphanit, Anucha
    ;
    Klysubun, Wantana
    ;
    Pecharapa, Wisanu
    In this work, X-ray diffraction (XRD), Raman spectroscopy (RAMAN) and vibrating sample magnetometer (VSM) measurements were employed to investigate the crystal structure, chemical bonding and magnetic properties of the nanocrystalline Zinc, Nickel and Nickel-Zinc ferrites (ZnFe<inf>2</inf>O<inf>4</inf>, NiFe<inf>2</inf>O<inf>4</inf> and Ni<inf>0.5</inf>Zn<inf>0.5</inf>Fe<inf>2</inf>O<inf>4</inf>) which were synthesized by sol-gel combustion method. Moreover, the composition of elements and the electronic structure including the cation distribution for all ferrite samples were examined through synchrotron X-ray fluorescence (XRF) and X-ray absorption near-edge structure (XANES) spectra. The overall characterization results indicate that the different amount of zinc and nickel ions in ferrites has crucial effect on their physical, magnetism and the site occupancy distribution of Fe<sup>3+</sup> ions. © (2013) Trans Tech Publications, Switzerland.
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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
    ;
    Ruangphanit, Anucha
    ;
    Klysubun, Wantana
    ;
    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.