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Subject: search.filters.subject.A. Sintering

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    Low temperature fabrication of lead-free KNN-LS-BS ceramics via the combustion method
    (2013-05-01)
    Wattanawikkam, Chakkaphan
    ;
    Vittayakorn, Naratip
    ;
    Bongkarn, Theerachai
    Lead-free piezoelectric 0.992(0.95K<inf>0.5</inf>Na<inf>0.5</inf>NbO <inf>3</inf>-0.05LiSbO<inf>3</inf>)-0.008BiScO<inf>3</inf>; KNN-LS-BS ceramics were successfully prepared using the combustion method. The highest % perovskite phase was found in the sample calcined at 700 °C for 1 h. The structural phase of orthorhombic structure was also detected in this sample. For the sintered ceramics, a pure tetragonal perovskite phase was observed in the samples sintered between 1025 and 1100 °C. The microstructure of ceramics showed a square or rectangular shape and the average grain size increased with increasing of sintering temperature. The density of the ceramics increased with increasing of sintered temperature up to 1075 °C, were it reached 97.5% of theoretical density and then dropped in value when the sintered temperature further increased. The excellent electrical properties of ε<inf>r</inf> at T<inf>c</inf>=6600, tanδ at T<inf>c</inf>=0.04, P<inf>r</inf> (at 40 kV/cm)=19.4 μC/cm<sup>2</sup> and E<inf>c</inf> (at 40 kV/cm)=24.1 kV/cm were obtained in the most dense ceramic. The results indicate that the KNN-LS-BS ceramics are promising lead-free piezoelectric materials. © 2012 Elsevier Ltd and Techna Group S.r.l.
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    Fabrication and electrical properties of Pb(Co1/3Nb2/3)O3 ceramics
    (2009-01-01)
    Unruan, M.
    ;
    Vittayakorn, N.
    ;
    Wongmaneerung, R.
    ;
    Prasatkhetragarn, A.
    ;
    Ananta, S.
    Pb(Co<inf>1/3</inf>Nb<inf>2/3</inf>)O<inf>3</inf> (PCN) ceramics have been produced by sintering PCN powders synthesized from lead oxide (PbO) and cobalt niobate (CoNb<inf>2</inf>O<inf>6</inf>) with an effective method developed for minimizing the level of PbO loss during sintering. Attention has been focused on relationships between sintering conditions, phase formation, density, microstructural development, dielectric and ferroelectric properties of the sintered ceramics. From X-ray diffraction analysis, the optimum sintering temperature for the high purity PCN phase was found at approximately 1050 and 1100 °C. The densities of sintered PCN ceramics increased with increasing sintering temperature. However, it is also observed that at very high temperature the density began to decrease. PCN ceramic sintered at 1050 °C has small grain size with variation in grain shape. There is insignificant change of dielectric properties with sintering temperature. The P-E hysteresis loops observed at -70 °C are of slim-loop type with small remanent polarization values, which confirmed relaxor ferroelectric behavior of PCN ceramics. © 2008 Elsevier Ltd and Techna Group S.r.l.