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Author: search.filters.author.Tangcharoen, ThanitSubject: search.filters.subject.sol-gel combustion

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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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    Synthesis, characterization and multiferroic properties of Ni 0.5Zn0.5Fe2O4-K0.5Na 0.5NbO3 nanocomposites
    (2013-01-01)
    Tangcharoen, Thanit
    ;
    Ruangphanit, Anucha
    ;
    Klysubun, Wantana
    ;
    Pecharapa, Wisanu
    In this work, nanocrystalline lead-free multiferroic composites of nickel zinc ferrite (Ni<inf>0.5</inf>Zn<inf>0.5</inf>Fe<inf>2</inf>O<inf>4</inf>) - potassium sodium niobate (K<inf>0.5</inf>Na<inf>0.5</inf>NbO<inf>3</inf>) were synthesized by a sol-gel combustion method. The influence of Ni <inf>0.5</inf>Zn<inf>0.5</inf>Fe<inf>2</inf>O<inf>4</inf> content, on the crystal structure, chemical bonding, morphologies, dielectric properties and magnetic behavior of K<inf>0.5</inf>Na<inf>0.5</inf>NbO<inf>3</inf> was investigated using X-ray diffraction measurement, Raman spectroscopy, scanning electron microscope, LCR meter and vibrating sample magnetometer, respectively. The overall characterization results indicate that the various contents of ferrite and ferroelectric materials in those composites have a significant influence on their multiferroic properties. In addition, this method is proven as one of an ordinary, fast and efficacious way to synthesize functional multiferroic materials with simple availability implements. © 2013 Copyright Taylor and Francis Group, LLC.