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Author: search.filters.author.Bongkarn, T.Subject: search.filters.subject.Microstructure

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    Use of the combustion technique for the preparation of Ba(Ti 0.70Zr0.30)O3 ceramics
    (2010-12-01)
    Phungjitt, N.
    ;
    Panya, P.
    ;
    Vittayakorn, N.
    ;
    Bongkarn, T.
    The preparation conditions for barium titanate zirconate [Ba(Ti <inf>0.70</inf>Zr<inf>0.30</inf>)O<inf>3</inf>] ceramics by the combustion method were studied. The X-ray diffraction pattern indicated that the calcined powders belonged to a cubic phase. The maximum percentage of the cubic perovskite phase was found in the sample calcined at 850°C. A pure cubic crystal structure was found in all ceramic samples. The average grain size increased with increasing sintering temperatures. The dielectric constant-temperature plots showed a maximum peak value of 5800 from ceramic sintered at 1350°C. The densities of samples corresponded to the dielectric constant. A diffuse phase transition was also observed.
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    Effect of calcination temperatures on microstructure and phase formation of Ba(Zr0.25Ti0.75)O3 powders
    (2008-12-01)
    Bongkarn, T.
    ;
    Phungjitt, N.
    ;
    Vittayakorn, N.
    In this work, the effect of calcination temperatures on the microstructure and phase formation of Ba(Zr<inf>0.25</inf>Ti<inf>0.75</inf>)O<inf>3</inf> (BZT) powders were investigated. The BZT powders were prepared via the solid state reaction method under various calcination temperatures. It was found that the second phases such as BaCO<inf>3</inf> ZrO<inf>2</inf>, BaZrO<inf>3</inf> and Ba<inf>2</inf>ZrO<inf>4</inf> existed in samples with calcination temperature below 1200 °C. Homogeneity and a highly pure perovskite phase of the BZT powders were obtained with calcination condition at 1300 °C for 4 h. Lattice parameter a and the percentage of cubic perovskite phase tended to increase with increasing calcination temperatures. The TG-DTA results corresponded to the XRD investigation. The microstructures of calcined powders exhibited an almost-spherical morphology and had a porous agglomerated form in all samples. The average particle sizes were increased from 0.2 to 1.1 μm when calcination temperatures were increased from 800 to 1350 °C. © 2008 Trans Tech Publications, Switzerland.