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Author: search.filters.author.Sukkha, UsaSubject: search.filters.subject.phase transition

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    Dielectric, ferroelectric and piezoelectric properties of the lead free 0.9BaTiO3-(0.1- x)Bi0.5Na0.5TiO3- x Bi(Mg0.5Ti0.5)O3 solid solution
    (2016-01-02)
    Mayamae, Jitkasem
    ;
    Sukkha, Usa
    ;
    Niemchareon, Surasak
    ;
    Muanghlua, Rangson
    ;
    Vittayakorn, Naratip
    Solid solution of 0.9BaTiO<inf>3</inf>-(0.1-x)Bi<inf>0.5</inf>Na<inf>0.5</inf>TiO<inf>3</inf>-xBi(Mg<inf>0.5</inf>Ti<inf>0.5</inf>)O<inf>3</inf> (BT-BNT-xBMT) system, where x = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10, was synthesized by the solid state reaction. Dense BT-BNT-xBMT ceramics were obtained by sintering at 1,150-1,250C for 4 h. The effect of BMT on crystal structure and electrical property of BT-BNT ceramics was investigated as a function of composition, x, using X-ray diffraction, dielectric spectroscopy, hysteresis and strain measurements. The crystal structure of solid solution BT-BNT-xBMT, where x = 0.00-0.10, successively transforms from tetragonal to pseudocubic symmetry, with increased BMT concentration. Temperature dependence of dielectric constant (ε<inf>r</inf>) and dielectric loss (tanδ) for BT-BNT-xBMT at various frequencies showed that phase transition of ceramics changed from ferroelectric to relaxor-like behavior as BMT content increased. Furthermore, remanent polarization (P<inf>r</inf>), coercive field (E<inf>c</inf>) and the normalized strain (d<inf>33</inf>∗) of BT-BNT-xBMT ceramics tend to decrease with increasing BMT concentration.
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    Effect of BiYbO3 Addition with a Small Tolerance Factor on Ferroelectricity and TC in PbZrO3 Ceramics
    (2015-10-08)
    Sukkha, Usa
    ;
    Niemcharoen, Surasak
    ;
    Vittayakorn, Naratip
    ;
    Guo, Ruyan
    ;
    Bhalla, Amar S.
    Perovskite (Pb(1-3x/2) Bi<inf>x</inf>)(Zr(1-3<inf>x/4</inf>) Yb<inf>x</inf>)O<inf>3</inf> (PZ-BY) ceramics, where x = 0.01-0.10, were synthesized by conventional solid state reaction. The effect of BiYbO<inf>3</inf> on crystal structure, phase transitions and electrical properties was studied as a function of composition. The X-ray diffraction (XRD) result indicated that the perovskite structure with orthorhombic symmetry was a major phase for all samples. The pyrochlore phase, identified as Yb<inf>0.2</inf>Zr<inf>0.8</inf>O<inf>1.9</inf>, coexists in PZ-BY ceramics. The influence of instability and a small tolerance factor (t) and the average electronegativity difference () of pure BY on phase formation of PZ-BY ceramic has been discussed. Furthermore, it was found that adding small tolerance factor BiYbO<inf>3</inf> compound can stabilize the antiferroelectric (AFE) phase of PZ solid solutions and decreasing t of solid solution can enhance Curie temperature of PZ.