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Author: search.filters.author.Bongkarn, T.Subject: search.filters.subject.Phase formation

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    Enhanced electrical and energy storage performances of Fe, Sb co-doped BNBCTS ceramics synthesized via the solid-state combustion technique
    (2024-12-01)
    Kornphom, C.
    ;
    Saenkam, K.
    ;
    Yotthuan, S.
    ;
    Vittayakorn, N.
    ;
    Bongkarn, T.
    In this study BNBCTS ceramics were co-doped with Fe and Sb to form (Bi<inf>0.5</inf>Na<inf>0.5</inf>)<inf>0.93</inf>(Ba<inf>0.945</inf>Ca<inf>0.055</inf>)<inf>0.07</inf>(Ti<inf>(0.9946-x)</inf>Sn<inf>0.0054</inf>)(Fe<inf>0.5</inf>Sb<inf>0.5</inf>)<inf>x</inf>O<inf>3</inf> ceramics (denoted as BNBCTS-xFS) with various x content and were prepared via the solid-state combustion technique to enhance the electrical and energy storage performance. The effect of co-doping Fe and Sb on the phase formation, defect dipole, microstructure, electrical and energy storage properties of BNBCTS-xFS ceramics was studied. When x content increased from 0.0 to 0.030, the amount of the rhombohedral (R) phase decreased from 51 to 24 % while the tetragonal (T) phase increased from 49 to 76 %. The increased Fe and Sb content increased the defect dipole of singly/doubly charged oxygen-vacancies (V<inf>O</inf><sup>∙</sup>/ V<inf>O</inf><sup>∙∙</sup>) and caused more Ti<sup>4+</sup> to transition to Ti<sup>3+</sup>, which caused the transition temperature of the ferroelectric phase to relaxor state (T<inf>F-R</inf>) in the ceramics to drop to below room temperature and it exhibited relaxor characteristics at room temperature. The ceramic with an x content of 0.010 had the largest grain size (3.06 μm), excellence ferroelectric properties (P<inf>r</inf> ∼31.04 μC/cm<sup>2</sup>, P<inf>m</inf> ∼38.98 μC/cm<sup>2</sup> and E<inf>c</inf> ∼18.28 kV/cm), the largest electro strain (∼0.175 %) and a large d<inf>33</inf><sup>*</sup> of 350 pm/V. Moreover, when x = 0.020, the ergodic relaxor ceramic showed the smallest grain size (1.03 μm), the lowest remanant polarization (P<inf>r</inf>) of 4.52 μC/cm<sup>2</sup> and the lowest coercive field (E<inf>c</inf>) of 8.37 kV/cm, at an electric field of 60 kV/cm. More importantly, energy storage properties at the electric breakdown strength (E<inf>b</inf> = 120 kV/cm) of the ceramics with an x content of 0.020 exhibited a recoverable energy storage density (W<inf>rec</inf>) of 1.81 J/cm<sup>3</sup>, a total energy storage density (W<inf>total</inf>) of 2.95 J/cm<sup>3</sup> and an efficiency (η) of 61.30%, with excellent thermal (∼25–150 °C) and frequency stability (∼1–100 Hz). This study provides new insights into the modulation of BNBCTS ceramics with Fe and Sb co-doping, which could effectively improve the electrical properties and energy storage properties of BNBCTS-xFS ceramics.
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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.