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Author: search.filters.author.Kornphom, ChittakornSubject: search.filters.subject.ferroelectric properties

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    Low firing temperatures and high ferroelectric properties of (Ba0.85Ca0.15)(Ti 0.90Zr0.10)O3 lead-free ceramics synthesized by the combustion technique
    (2016-01-26)
    Kornphom, Chittakorn
    ;
    Vittayakorn, Naratip
    ;
    Bongkarn, Theerachai
    This work studied the effect of firing conditions on phase formation, microstructure and electrical properties of (Ba<inf>0.85</inf>Ca<inf>0.15</inf>)(Ti<inf>0.90</inf>Zr<inf>0.10</inf>)O<inf>3</inf>;(abbreviated as BCTZ) ceramics, which were synthesized through the combustion technique. To reduce the reaction temperature, glycine was used as fuel with a ratio of raw material: glycine (1:1.11). BCTZ samples were calcined at 900-1200°C for 2 h and sintered at 1350 -1550°C for 2 h. Ultrafine BCTZ powder and single peroveskite phase were achieved from the sample calcined at 1050°C for 2 h.These results were obtained at a lower temperature and with shorter dwell time than those obtained using the solid state reaction method by ∼150°C and 1 h, respectively. The BCTZ ceramics exhibited a coexistence of rhombohedral and orthorhombic phase in all samples. The average particle size and the average grain size increased from 172 to 295 nm and 0.82 to 2.57 μm, respectively, when firing temperatures increased. The highest density (5.76 g/cm<sup>3</sup>), highest dielectric constant (ε<inf>r</inf> ≅ 4485 and ε<inf>max</inf> ≅ 14897) and best ferroelectric properties (P<inf>r</inf> ≅ 18.47 C/cm<sup>2</sup> and E<inf>C</inf> ≅ 4.52 kV/cm) were obtained from the sample sintered at 1450°C for 2 h.
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    Fabrication of 0.62[0.75PMN-0.25PYbN]-0.38PT ceramics using one step calcination via combustion technique
    (2013-01-01)
    Kornphom, Chittakorn
    ;
    Bhupaijit, Pamornnarumol
    ;
    Vittayakorn, Naratip
    ;
    Bongkarn, Theerachai
    The fabrication of 0.62[0.75Pb(Mg<inf>1/3</inf>Nb<inf>2/3</inf>)O <inf>3</inf>-0.25Pb(Yb<inf>1/2</inf>Nb<inf>1/2</inf>)O<inf>3</inf>]-0. 38PbTiO<inf>3</inf> ceramics (abbreviated PMN-PYbN-PT) by combustion technique using one step calcination was studied. Glycine was used as fuel to reduce the reaction temperature. The phase formation, microstructure, density and dielectric properties were investigated. It was shown that calcination method is more effective than conventional solid state reaction. The crystal structure of PMN-PYbN-PT ceramics exhibited a single rhombohedral perovskite phase in samples sintered at temperature T < 1200°C. The pyrochlore phase was found in the samples sintered at 1200°C. The average grain size of the ceramics increases with increasing sintering temperature. The density and the maximum dielectric constant increases with increasing sintering temperatures up to 1150°C, and then decreases at higher temperatures. The maximum density (8.04 g/cm<sup>3</sup>), highest dielectric constant (19000) and excellent ferroelectric properties (P<inf>r</inf> ∼ 41.05 μC/cm<sup>2</sup>and E<inf>c</inf> ∼ 8.1 kV/cm) were obtained for the sample sintered at 1150°C. © 2013 Copyright Taylor and Francis Group, LLC.