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    Sintering Temperature Effect on Phase Formation, Microstructure and Electrical Properties of Modified KNLNTS Solid Solution Prepared via the Solid-State Combustion Technique
    (2023-01-01)
    Kornphom, Chittakorn
    ;
    Thawong, Pichittra
    ;
    Khiwoon, Suprakorn
    ;
    Vittayakorn, Naratip
    ;
    Bongkarn, Theerachai
    In this study, the effect of sintering temperature (1000–1100 °C for 2 h) on phase formation, phase transition, microstructure and electrical properties of lead-free piezoelectric (K<inf>0.44</inf>Na<inf>0.52</inf>Li<inf>0.04</inf>)(Nb<inf>0.84</inf>Ta<inf>0.10</inf>Sb<inf>0.06</inf>)O<inf>3</inf> (KNLNTS) solid solution with 0.3 wt%Bi<inf>2</inf>O<inf>3</inf> + 0.4 wt%Fe<inf>2</inf>O<inf>3</inf> + 0.2 wt%CuO additive (abbreviate as modified KNLNTS) was investigated. Modified KNLNTS ceramics were synthesized by the solid-state combustion technique using glycine as fuel. The modified KNLNTS powders were prepared using the calcination condition of 650 °C for 2 h. The XRD pattern of all sintered ceramics exhibited a pure perovskite phase. Using Rietveld refinement to analyze the phase formation showed that the modified KNLNTS ceramics had co-existing phases of orthorhombic and tetragonal in all sintered ceramics and the orthorhombic phase increased when the sintering temperature increased. The average grain size, T<inf>O-T</inf>, T<inf>c</inf>, P<inf>r</inf> and Ec increased with increasing sintering temperature. At the sintering temperature of 1025 °C, the modified KNLNTS ceramic showed the best electrical properties (C<inf>ε</inf> ≈ 6745, S<inf>max</inf> ≈0.274% and d*<inf>33</inf> ≈ 548 pm/V). The good electrical properties of the modified KNLNTS ceramics makes them good candidates for lead-free applications to replace Pb-based ceramics.
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    Effects of the phase content and grain size on the electrical and energy storage properties of lead-free BNBT ceramics with substituted La3+
    (2022-01-01)
    Thatawong, Bhoowadol
    ;
    Rittidech, Aurawan
    ;
    Vittayakorn, Naratip
    ;
    Bongkarn, Theerachai
    Lead-free [(Bi<inf>0.5</inf>Na<inf>0.5</inf>)<inf>0.94</inf>Ba<inf>0.06</inf>]<inf>1-x</inf>La<inf>x</inf>TiO<inf>3</inf> (BNBT-xLa) ceramics with x = 0, 0.01, 0.02, 0.03, 0.04, 0.05 and 0.06 mol.% were synthesized by the solid-state combustion technique with calcination and sintering temperatures of 750 °C and 1150 °C, respectively, for 2 h. The phase formation, microstructure, dielectric, ferroelectric and energy storage properties of the BNBT-xLa ceramics were investigated. The XRD patterns of the powders showed a pure perovskite phase for all samples. The average particle size increased from 298 to 379 nm with increasing x. All ceramics showed coexisting rhombohedral and tetragonal phases. When x rose, the content of the tetragonal phase increased, as validated by the Rietveld refinement method. The average grain size decreased from 1.43 to 0.81 µm when x increased from 0 to 0.05 and then started to increase. The Curie temperature (T <inf>d</inf>) of the samples shifted to lower temperatures with rising x, owing to an increased tetragonal phase. The maximum dielectric constant (ε <inf>m</inf>), remanent polarization (P <inf>r</inf>) and coercive field (E <inf>c</inf>) decreased with increasing x. The BNBT-0.05La ceramic exhibited the smallest grain size, and lowest P <inf>r</inf> = 0.8 µC/cm<sup>2</sup> and E <inf>c</inf> = 2.9 kV/cm, with the highest energy storage efficiency (η ∼ 78.31%) and a large effective energy storage density (W ∼ 0.83 J/cm<sup>3</sup>) measured in an electric field of 80 kV/cm.
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    Effect of BFCO Doping on Phase Structure, Microstructure, Electric and Magnetic Properties of BNKLT Ceramics Prepared by the Combustion Method
    (2021-01-01)
    Thawong, Pichittra
    ;
    Bongkarn, Theerachai
    ;
    Jantasurin, Jirawat
    ;
    Pinitsoontorn, Supree
    ;
    Charoonsuk, Thitirat
    Lead free solid solution Bi<inf>0.5</inf>(Na<inf>0.68</inf>K<inf>0.22</inf>Li<inf>0.10</inf>)<inf>0.5</inf>TiO<inf>3</inf>-xmol%Bi<inf>2</inf>FeCrO<inf>6</inf> (BNKLT-xBFCO), with x = 0, 0.004, 0.007, 0.013 and 0.019, ceramics were calcined at 750 °C and sintered at 1150 °C for 2 h using the solid state combustion technique. The effect of the x content on the phase formation, microstructure, electric and magnetic properties of the produced ceramics were investigated. All samples exhibited a pure perovskite phase with the co-existence of rhombohedral and tetragonal phases. The doping of BFCO enhanced the density and dielectric properties of the BNKLT ceramics. The BNKLT-0.013BFCO ceramics showed the highest density (5.87 g/cm<sup>3</sup>), excellent dielectric properties (ε <inf>R</inf> ∼1390, tan δ <inf>R</inf> ∼0.039, ε <inf>m</inf> ∼4986 and tan δ <inf>m</inf> ∼0.075) and the highest piezoelectric constant (d<inf>33</inf>∼194 pC/N). The sample with x = 0 showed diamagnetic behavior, while the samples with 0.004-0.019 content exhibited paramagnetic behavior with higher magnetization at higher x content.
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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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    The effect of firing temperatures on (Pb0.75Ba 0.25)(Zr0.70Ti0.30)O3 ceramics prepared via the combustion technique
    (2013-12-01)
    Sittiketkorn, Panadda
    ;
    Wongtey, Pongkiti
    ;
    Vittayakorn, Naratip
    ;
    Bongkarn, Theerachai
    The (Pb0.7<inf>5</inf>Ba0.2<inf>5</inf>)(Zr<inf>0.70</inf>Ti <inf>0.30</inf>)O<inf>3</inf> (PBZT) ceramics were prepared via the combustion technique. (CO(NH<inf>2</inf>)<inf>2</inf>) was used as a fuel. The effect of firing temperature on PBZT's phase formation, microstructure and electrical properties were investigated. The calcination and sintering temperatures were 600°C-1000°C and 1100°C-1300°C. The pure rhombohedral perovskite was obtained from the powders calcined at 850°C. The average particle size tended to increase with increased calcination temperatures. A pure rhombohedral perovskite phase was found in all pellet samples. The average grain size and linear shrinkage tended to increase from 0.57 to 2.15 μm and from 6.8 to 15.8% with increased sintering temperatures. The dielectric results indicated the relaxer behavior of PBZT ceramics. The Curie temperature tended to decrease with increasing sintering temperatures. The highest density (∼7.39 g/cm <sup>3</sup>) and highest dielectric constant (∼8620) were obtained by using the combustion technique which was higher than the conventional mixed oxide method. © 2013 Copyright Taylor and Francis Group, LLC.