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Author: search.filters.author.Luangpangai, AnupongSubject: search.filters.subject.dielectric

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    Phase formation and electrical properties of SBNLT ceramics prepared via combustion technique
    (2023-01-01)
    Sinkruason, Thanapon
    ;
    Luangpangai, Anupong
    ;
    Charoenthai, Nipaphat
    ;
    Rittidech, Aurawan
    ;
    Pulphol, Phieraya
    This report investigates the effect of firing temperatures on the phase formation, microstructure, electrical, and energy storage properties of lead-free Sr<inf>0.3</inf>(Bi<inf>0.7</inf>Na<inf>0.67</inf>Li<inf>0.03</inf>)<inf>0.5</inf>TiO<inf>3</inf> (SBNLT) ceramics, synthesised by combustion technique. The samples were calcined between 700°C and 900°C for 2 h and sintered between 1100°C and 1200°C for 2 h. The ceramics exhibited coexisting rhombohedral and tetragonal phases, which were confirmed by the Rietveld refinement technique. A morphotropic phase boundary (MPB) of the rhombohedral and tetragonal phases, with a ratio of 49:51, was obtained at the sintering temperature of 1175°C. The highest maximum dielectric constant (ε <inf>max</inf>= 4667), polarisation (P <inf>max</inf>= 28.80 µC/cm<sup>2</sup>) and energy density (W = 0.95 J/cm<sup>3</sup>), with a breakdown strength of 70 kV/cm, were achieved from the sample sintered at 1175°C.
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    Enhancement of the Dielectric and Energy Storage Properties of Lead-Free BNSLT Ceramics by Zr4+ Substitution into B-Sites
    (2023-01-01)
    Luangpangai, Anupong
    ;
    Noiphoowiang, Nachtarika
    ;
    Premwichit, Pathit
    ;
    Klinbanmor, Metarsit
    ;
    Vittayakorn, Naratip
    (Bi<inf>0.38</inf>Na<inf>0.30</inf>Sr<inf>0.28</inf>)<inf>0.98</inf>La<inf>0.02</inf>Ti<inf>1-x</inf>Zr<inf>x</inf>O<inf>3</inf> (abbreviated as BNSLT<inf>1-x</inf>Zr<inf>x</inf>, with x = 0 − 0.05) lead free ceramics were fabricated using the solid-state combustion method. The phase structure, microstructure and electrical properties of the ceramics were investigated. The coexistence of the rhombohedral (R) and tetragonal (T) phases was found in all samples. Rietveld refinement confirmed that as x increased from 0 to 0.05, the rhombohedral phase increased from 41 to 60%. A nearly equal R:T phase ratio of 49:51 was obtained for x = 0.01. All ceramics displayed polygonal grain shapes with anisotropic grain growth. The average grain size of the ceramics was in the range of 0.46–0.79 µm. The optimal Zr<sup>4+</sup> content resulted in increased grain growth and reduced pores, leading to improved electrical properties. The highest density (5.52 g/cm<sup>3</sup>), maximum dielectric constant (ε <inf>m</inf> =2156), maximum polarization (P<inf>max</inf>=15.36 µC/cm<sup>2</sup>) and high energy storage properties (W<inf>total</inf>=0.49 J/cm<sup>3</sup>, W<inf>rec</inf>=0.45 J/cm<sup>3</sup>, W<inf>loss</inf>=0.05 J/cm<sup>3</sup> and η = 90.54% at 60 kV/cm) were obtained from x = 0.01 caused by a morphotropic phase boundary (MPB) and good morphology.
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    Phase Structure, Microstructure, and Electrical Properties of Bi0.47Na0.47Ba0.06TiO3 Ceramics with (LiNb)4+ Substituted into B-Sites
    (2023-01-01)
    Luangpangai, Anupong
    ;
    Thatawong, Bhoowadol
    ;
    Charoenthai, Nipaphat
    ;
    Vittayakorn, Naratip
    ;
    Bongkarn, Theerachai
    Due to the substitution of complex ions into B-sites is very interesting in recent, lead-free Bi<inf>0.47</inf>Na<inf>0.47</inf>Ba<inf>0.06</inf>Ti<inf>1−</inf><inf>x</inf> (LiNb) <inf>x</inf> O<inf>3</inf> (BNBT<inf>1−</inf><inf>x</inf> LN <inf>x</inf>) ceramics (with x = 0–0.04) were fabricated by the solid-state combustion method. The influence of (LiNb)<sup>4+</sup> (x) on the phase structure, microstructure, and electrical properties was investigated. The X-ray diffraction (XRD) patterns exhibited a pure perovskite structure for all specimens. Coexisting rhombohedral and tetragonal phases were observed in all samples and the tetragonal phase increased with increased x, as analyzed by the Rietveld refinement method. The morphology of the BNBT<inf>1−</inf><inf>x</inf> LN <inf>x</inf> ceramics, obtained by scanning electron microscopy (SEM), revealed almost-round grain shapes and anisotropic grain growth. The density and average grain sizes decreased from 5.84 to 5.54 g/cm<sup>3</sup> and 1.7 to 0.9 µm, respectively, when x increased from 0 to 0.04. The grain size distribution decreased with increased (LiNb)<sup>4+</sup> content. A reduction in the dielectric properties was observed, due to the phase ratio changing away from a morphotropic phase boundary (MPB), an inferior microstructure, and low density caused by (LiNb)<sup>4+</sup> substitution. The (LiNb)<sup>4+</sup> substitution induced the transition from non-ergodic relaxor to ergodic relaxor ferroelectric state.
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    Effect of substitution of (NiNb)4+ into B-sites on the phase formation, microstructure and electrical properties of Bi0.47Na0.47Ba0.06TiO3 ceramics
    (2022-01-01)
    Luangpangai, Anupong
    ;
    Bhupaijit, Pamornnarumol
    ;
    Charoenthai, Nipaphat
    ;
    Vittayakorn, Naratip
    ;
    Thountom, Sarawut
    Bi<inf>0.47</inf>Na<inf>0.47</inf>Ba<inf>0.06</inf>Ti<inf>1-x</inf>(Ni<inf>1/3</inf>Nb<inf>2/3</inf>)<inf>x</inf>O<inf>3</inf> ceramics (abbreviated as BNBT<inf>1-x</inf>(NN)<inf>x</inf>, x = 0, 0.01, 0.03 and 0.05) were synthesized by solid-state combustion. The effect of x on the phase formation, microstructure and electrical properties of BNBT<inf>1-x</inf>(NN)<inf>x</inf> ceramics was examined. The XRD pattern indicated the coexistence of rhombohedral and tetragonal phases in all the specimens. Moreover, Rietveld refinement confirmed that the tetragonal phase increased from 47 to 71% when x increased from 0 to 0.05. The morphology of BNBT<inf>1-x</inf>(NN)<inf>x</inf> ceramics was observed by SEM and the ceramics grains showed polygonal shapes and the grain growth tended to be anisotropic. With (NiNb)<sup>4+</sup> substitution, the average grain sized decreased rapidly from 1.7 to 1.0 µm and the grain size distribution was narrower as the amount of (NiNb)<sup>4+</sup> increased. The density, remnant polarization (P<inf>r</inf>) and coercive field (E<inf>c</inf>) rapidly decreased with increasing x. A significant decrease in the ferroelectric properties was caused by the increasing tetragonal phase.