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Author: search.filters.author.Sumang, RattiphornSubject: search.filters.subject.dielectric properties

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    Improvement of phase structure and energy storage properties of [(0.72-x)Bi0.5Na0.5TiO3-0.28SrTiO3-xBaZr0.05Ti0.95O3] lead-free ceramics
    (2022-01-01)
    Panpho, Phakakorn
    ;
    Thongmee, Navavan
    ;
    Mathrmool, Krailas
    ;
    Unruan, Muangjai
    ;
    Vitayakorn, Narathip
    Lead-free [(0.72-x)Bi<inf>0.5</inf>Na<inf>0.5</inf>TiO<inf>3</inf>-0.28SrTiO<inf>3</inf>-xBaZr<inf>0.05</inf>Ti<inf>0.95</inf>O<inf>3</inf>] ceramics (abbreviated as BNT-ST-xBZT), x = 0, 0.03, 0.05, 0.07, 0.10, and 0.15 wt.%, were prepared by conventional solid-state reaction method. The effect of x(BZT) content on phase structure, microstructure, dielectric, ferroelectric, and energy storage properties of BNT-BT-x(BST) ceramics was studied. The samples of the study were analyzed through X-ray diffraction (XRD). The XRD patterns were analyzed using Rietveld refinement. The XRD revealed a single-phase perovskite for all the samples with coexisting rhombohedral and tetragonal phases. It shows the increasing of x(BZT) content and, more tetragonal distortion of the phase. The scanning electron micrographs (SEM) of all the samples displayed spherical-like morphology. The grain growth inhibited by increasing of x(BZT) content. The average of grain size decreased from 2.74 µm to 0.65 µm with BZT content. The highest density (ρ = 5.31 ± 0.11 g/cm<sup>3</sup>), recoverable energy storage density (W <inf>rec</inf> = 0.234 J/cm<sup>3</sup>), and energy storage efficiency (η = 90%) at 30 kV/cm were found in the composition of x(BZT) = 0.05 wt.%.
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    Synthesis and Characterization of KNN Modified BNT-ST Ceramics for Energy Storage Applications
    (2021-01-01)
    Thongmee, Navavan
    ;
    Klaytae, Thanawat
    ;
    Vittayakorn, Naratip
    ;
    Bongkarn, Theerachai
    ;
    Sumang, Rattiphorn
    Lead-free [(0.76-x)Bi<inf>0.5</inf>Na<inf>0.5</inf>TiO<inf>3</inf>–0.24SrTiO<inf>3</inf>–x(K<inf>0.5</inf>Na<inf>0.5</inf>)NbO<inf>3</inf>; BNT-ST-KNN] ceramics with x = 0, 0.03, 0.05, 0.07, 0.10, 0.15 wt.% were synthesized by using a solid-state reaction method. The effect of x content on phase, microstructure electrical and energy density properties was investigated. The samples were analyzed by X-ray diffraction (XRD) and the XRD patterns were fitted using the Rietveld refinement. The grain growth is obviously inhibited and smaller grains are formed in the ceramic samples at a high concentration of x. Dielectric study confirmed relax or nature with a drastic decrease of T <inf>max</inf> with the increase of x content in BNT-ST-KNN system. The maximum density (ρ = 5.42 (Formula presented.) 0.13 g/cm<sup>3</sup>), highest dielectric constant (ε<inf>r</inf> =3300) with tanδ∼0.05, high recoverable energy storage density (W <inf>rec</inf>=0.16 J/cm<sup>3</sup>) with energy storage efficiency of (η = 64) were obtained in x = 0.03 wt.% ceramic samples, which suggested its usefulness for energy-storage capacitor applications.
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    The effect of excess PbO on crystal structure, microstructure and dielectric properties of (Pb0.50Sr0.50)TiO3 ceramics
    (2013-01-01)
    Sumang, Rattiphorn
    ;
    Vittayakorn, Naratip
    ;
    Bongkarn, Theerachai
    Lead strontium titanate [(Pb5<inf>0</inf>Sr5<inf>0</inf>)TiO<inf>3</inf>; PST] ceramics were fabricated by the conventional solid state reaction method using calcination and sintering temperatures of 950°C and 1250°C. To prevent PbO evaporation during the firing processes, excess PbO was added to the samples in varying amounts from 0-10 wt.%. It was found that PST powders indexed in a tetragonal structure. Impurity phases were detected in the calcined powders which had excess PbO higher than 3 wt%. A pure perovskite phase was obtained from all ceramic samples. The lattice parameters a, c and the c/a ratio decreased with an increasing excess of PbO. The average particle size and the average grain size increased with the increase of PbO. The porous microstructure slightly decreased with an increasing amount of PbO, up to 1 wt.%, then slightly increased with higher excess PbO. The density can be improved by adding 1 wt.% of excess PbO. The dielectric constant increased from 7500 for the 0 wt.% sample to 8300 for the 1 wt%. This was followed by reductions for 3, 5 and 10wt.%. The Curie temperature and transition enthalpy slightly increased with an increase amount of PbO until 1 wt.%, then slightly decreased, for the higher excess PbO. © 2013 Copyright Taylor and Francis Group, LLC.