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Author: search.filters.author.Bongkarn, TheerachaiSubject: search.filters.subject.Perovskite

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    Efficient and novel synthesis of Nb-doped SrTiO3 nanoparticles via microwave-assisted sol-gel auto-combustion
    (2025-02-01)
    Nunocha, Pornnipa
    ;
    Bongkarn, Theerachai
    ;
    Eiad-ua, Apiluck
    ;
    Channei, Duangdao
    ;
    Suriwong, Tawat
    This study employed microwave-assisted sol-gel auto-combustion to synthesize niobium-doped strontium titanate (SrTi<inf>1-x</inf>Nb<inf>x</inf>O<inf>3</inf>, STNO) nanoparticles, targeting enhanced photocatalytic performance applications. The STNO with varying levels of Nb doping (x = 0 to 0.05), was successfully synthesized utilizing the rapid and novel microwave-assisted sol-gel auto-combustion technique. The synthesized nanoparticles consistently exhibited a pure cubic perovskite structure across all doping levels, as confirmed by Rietveld refinement, which also showed an increase in lattice parameters and unit cell volume with higher Nb content. Morphological analysis revealed uniformly cubic-shaped particles with sizes ranging from 60 to 180 nm. The bandgap energy (E<inf>g</inf>) remained unaffected by the varying Nb doping levels. Regarding photocatalytic activity for the degradation of methylene blue (MB) dye and tetracycline (TC) antibiotic under UV-A LED irradiation, the photocatalytic performance of STNO was significantly enhanced with increasing Nb content. The optimal photocatalytic decolorization was achieved at x = 0.05, aligning well with findings derived from photoluminescence (PL), E<inf>g</inf>, Nyquist plot analyses and band edge potentials. Therefore, microwave-assisted sol-gel auto combustion is one of the efficient and novel methods to synthesize metal oxide materials.
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    INFLUENCE OF Pr6O11-DOPING ON THE CRYSTAL STRUCTURE AND ELECTRICAL PROPERTIES OF BNBT PIEZOELECTRIC CERAMICS
    (2025-01-01)
    Yotthuan, Surirat
    ;
    Sawangboon, Nuttawan
    ;
    Meechoowas, Ekarat
    ;
    Bongkarn, Theerachai
    ;
    Vittayakorn, Naratip
    In this work, a series of lead-free 0.97(Bi<inf>0.5</inf>Na<inf>0.5</inf>)TiO<inf>3-</inf>0.03BaTiO<inf>3-x</inf>Pr<inf>6</inf>O<inf>11</inf> (BNBT-xPr) piezoelectric materials with x=0, 0.1, 0.3, 0.5, and 0.7 wt.% were created by the solid-state combustion route, to enhance their electric properties. The investigation on the phase evolution, microstructure, and electrical behavior of the specimens were carried out. The powders and ceramics were calcined and sintered for two hours at 800℃ and 1180℃, correspondingly. All examples displayed a perfect perovskite lattice and no detectable impurity phase. XRD pattern examination for the ceramics disclosed the existence of rhombohedral and tetragonal phases in all examples. The rhombohedral phase was boosted by rising the doping levels, as established by the Rietveld refinement study. As the x content rose, the average grain size and measured density began to decrease from 0.90±0.10 to 0.73±0.07 μm and 6.13 to 6.05 g/cm<sup>3</sup>, correspondingly. It was noticed that Pr<inf>6</inf>O<inf>11</inf> doping, decreased dielectric properties. The remnant polarization (Pr) of the samples rises from 22.2 to 27.7 μC/cm<sup>2</sup> with x rises from 0 to 0.3 and then dropped. The coercive field (Ec) of the ceramics rises significantly when Pr<inf>6</inf>O<inf>11</inf> was incorporated. The BNBT lead-free ceramics doped with 0.3wt%Pr<inf>6</inf>O<inf>11</inf>, with a high Pr value, could be a promising candidate for memory applications to replace Pb-based ceramics.