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    Item type:Publication,
    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
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    Thawong, Pichittra
    ;
    Khiwoon, Suprakorn
    ;
    ;
    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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    Item type:Publication,
    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.