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Author: search.filters.author.Bongkarn, TheerachaiSubject: search.filters.subject.Ferroelectric properties

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    Optimal Bi₀.₈Ba₀.₂FeO₃ doping in Bi₀.₅(Na₀.₇₇K₀.₂₀Li₀.₀₃)₀.₅TiO₃ multiferroic ceramics synthesized by the solid-state combustion technique
    (2025-12-01)
    Thawong, Pichittra
    ;
    Prasertpalichat, Sasipohn
    ;
    Suriwong, Tawat
    ;
    Pinitsoontorn, Supree
    ;
    Jantaratana, Pongsakorn
    (1-x)Bi<inf>0.5</inf>(Na<inf>0.77</inf>K<inf>0.20</inf>Li<inf>0.03</inf>)<inf>0.5</inf>TiO<inf>3</inf>-xBi<inf>0.8</inf>Ba<inf>0.2</inf>FeO<inf>3</inf> ((1-x)BNKLT-xBBF) ceramics with x = 0-0.4 were synthesized by the solid-state combustion technique. X-ray diffraction (XRD) analysis confirmed a pure perovskite structure with coexisting rhombohedral and tetragonal phases. Rietveld refinement revealed that the unit cell volume increased with increased x due to the substitution of smaller Bi<sup>3+</sup> and Ti<sup>4+</sup> ions by larger Ba<sup>2+</sup> and Fe<sup>3+</sup> ions at the A- and B-sites, respectively. The average grain size and measured density also increased with increasing x, while the resistivity decreased. At room temperature, (1-x)BNKLT-xBBF ceramics with x = 0.2–0.4 exhibited multiferroic behavior, characterized by ferroelectric and ferromagnetic hysteresis loops. The 0.8BNKLT-0.2BBF ceramic exhibited the most favorable properties, including: the highest relative density (95.48%), the highest dielectric constant and low dielectric loss at room temperature (ε<inf>R</inf> = 1746 and tan δ<inf>R</inf> = 0.0296), good ferroelectric properties (P<inf>r</inf>=6.46 µC/cm<sup>2</sup> and E<inf>c</inf>=11.84 kV/cm) and good ferromagnetic properties (M<inf>r</inf>=0.002 emu/g, H<inf>c</inf>=110 Oe and α<inf>E</inf> = 1.092 mV/Oe·cm). These results indicate that 0.8BNKLT-0.2BBF has the potential for applications in lead-free, room temperature multiferroic applications.
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    Influence of strontium doping on the ferroelectric and piezoelectric properties of lead zinc niobate-lead zirconate titanate ceramics
    (2007-12-01)
    Vittayakorn, Naratip
    ;
    Bongkarn, Theerachai
    The crystal structure, ferroelectric and piezoelectric properties of pyrochlore-free lead zinc niobate-lead zirconate titanate ceramics were investigated systematically as a function of Sr doping as well as thermal treatment. The results showed that the remanent polarization (P<inf>r</inf>) has decreased significantly with increase in strontium content. After annealing, the value of squareness of hysteresis loop (R<inf>sq</inf>) increased from 1.48 to 1.74 for the annealed sample. Furthermore the annealed samples exhibited larger Pr and lower coercive fields (E<inf>c</inf>) compared with as-sintered samples. The results indicated that the ferroelectric and piezoelectric properties in Sr-modified PZT-PZN were further improved by thermal annealing.
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