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    Classical to Relaxor Ferroelectric Transformation of Lanthanum Modified BaTi0.91Sn0.09O3 Ceramics
    (2023-01-01)
    Pattanakasem, Wiwat
    ;
    Prasertpalichat, Sasipohn
    ;
    Premwichit, Pathit
    ;
    Vittayakorn, Naratip
    ;
    Bongkarn, Theerachai
    Lead-free Ba<inf>1-x</inf>La<inf>x</inf>Ti<inf>0.91</inf>Sn<inf>0.09</inf>O<inf>3</inf> (BLTS) ceramics with x = 0, 0.01, 0.03 and 0.05, were prepared by the traditional solid-state sintering method with calcination and sintering temperatures of 1200 °C for 2 h and 1400 °C for 4 h, respectively. X-ray diffraction (XRD) measurements revealed that all the BLTS ceramics had pure perovskite structures with no detectable impurities. When x = 0 and 0.01, the ceramics exhibited coexisting orthorhombic (O) and tetragonal (T) phases, while the orthorhombic (O), tetragonal (T) and cubic phase (C) were detected in the BLTS ceramics with x = 0.03 and 0.05, which the Rietveld refinement analysis confirmed. Furthermore, increasing x in the BLTS ceramics led to a large decrease in the average grain size (from 45.7 to 0.9 µm). A significant decrease in the remnant polarization (P <inf>r</inf>) accompanied by very slim hysteresis loops were observed for higher La (x ≥ 0.03) levels. This demonstrates that BLTS ceramics transition from classical ferroelectric to relaxor ferroelectric behavior due to changing occupancy of the A-site to La<sup>3+</sup> from Ba<sup>2+</sup>.
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    Influence of sintering temperature on phase formation, microstructure and dielectric properties of calcium and strontium Doped BNT ceramics prepared via combustion technique
    (2013-01-01)
    Sittiketkorn, Panadda
    ;
    Laowanidwatana, Artid
    ;
    Vittayakorn, Naratip
    ;
    Bongkarn, Theerachai
    Influence of sintering temperature on phase formation, microstructure and dielectric properties of calcium and strontium doped BNT ceramics (BNTST20 and BNTCT2) were investigated. The BNTST20 and BNTCT2 ceramics were prepared using the combustion technique. The structural phase of the BNTST20 ceramics indexed in a cubic phase, while the BNTCT2 ceramics indexed in a rhombohedral phase. The average grain size tended to increase with increasing sintering temperature. The density and the dielectric constant at Curie temperatures increased with increasing sintering temperature up to 1200°C and 1150°C, thereafter they decreased for BNTST20 and BNTCT2 ceramics, respectively. Moreover, the highest density (5.59 and 5.57 g/cm<sup>3</sup>) ceramics exhibited the highest dielectric constant at Curie temperatures (∼4733 and ∼3218) for BNTST20 and BNTCT2, respectively. The ferroelectric properties were also investigated. © 2013 Copyright Taylor and Francis Group, LLC.