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    Effect of A-site and B-site ion replaced with small ions on the intermediate phase in PbZrO3 ceramic
    (2014-02-14)
    Sukkha, Usa
    ;
    Vittayakorn, Wanwilai
    ;
    Muanghlua, Rangson
    ;
    Niemcharoen, Surasak
    ;
    Vittayakorn, Naratip
    The solid solution of (1 - x)PbZrO<inf>3</inf>-xNaNbO<inf>3</inf> ceramics, where x = 0.0-0.08, was synthesized by solid state reaction. The basic characterizations were performed using X-ray diffraction (XRD), dielectric spectroscopy, hysteresis measurement and differential scanning calorimetry (DSC) techniques. The results indicated that the crystal structure of the solid solution, (1 - x)PZ-xNN, where x = 0.00-0.08, is of orthorhombic symmetry. It was found that the effect of NN being replaced with small ions at the A-site and B-site can induce an AFE-like phase in PZ. The FE intermediate phase of PZ cannot be induced, although Zr<sup>4+</sup> ions were substituted by small Nb<sup>5+</sup> ions. This is due to the decreasing average rate of radii in the A-site (0.1 Å mol<sup>-1</sup>) being higher than that in the B-site (0.08 Å mol<sup>-1</sup>). © 2013 Elsevier B.V. All rights reserved.
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    The effect of post-sintering annealing induced extrinsic dielectric properties in PZT-PZN ceramics
    (2007-08-02)
    Vittayakorn, Naratip
    ;
    Cann, David P.
    ;
    Rujijanagul, Gobwute
    ;
    Tunkasiri, Tawee
    Pb[(Zr1/2Ti1/2)0.7(Zn1/3Nb2/3)0.3]O3 (PZT-30PZN) powder was prepared using the columbite precursor method. The phase development of calcined powder precursors was analyzed by X-ray diffraction. Dielectric and ferroelectric properties of the as-sintered and annealed samples were measured and correlated with microstructure. The morphology evolution was determined by a scanning electron microscopy (SEM) technique. The as-sintered ceramic exhibited weak relaxor-ferroelectric behavior, with a relatively low dielectric constant maximum measured at 1 kHz (Km@1 kHz) of 14 000. Annealing resulted in a transition to normal-ferroelectric-like behavior, a shift in the dielectric maximum temperature from 310C to 300C, and a dramatic increase of Km@1 kHz to a maximum value of 25 100 for the longer anneal. After thermal annealing at 900C for 1 week a strong enhancement of remanent polarization (Pr) was observed.
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    Investigation of the influence of thermal treatment on the morphologies, dielectric and ferroelectric properties of PZT-based ceramics
    (2007-08-16)
    Vittayakorn, Naratip
    ;
    Rujijanagul, Gobwute
    ;
    Cann, David P.
    Pb[(Zr<inf>1/2</inf>Ti<inf>1/2</inf>)<inf>0.9</inf>(Zn<inf>1/3</inf>Nb<inf>2/3</inf>)<inf>0.1</inf>]O<inf>3</inf> (PZT-10PZN) powder was prepared using the columbite precursor method. The phase development of calcined powder precursors was analyzed by X-ray diffraction. Dielectric and ferroelectric properties of the as-sintered and annealed samples were measured and correlated with the microstructure. The morphological evolution was determined by scanning electron microscopy (SEM). The as-sintered ceramic exhibited weak normal-ferroelectric behavior, with a relatively low dielectric constant maximum measured at 1 kHz (ε<inf>rmax</inf> at 1 kHz) of 13,000. Annealing resulted in a transition to relaxor-ferroelectric-like behavior, a shift in the dielectric maximum temperature from 360 to 350 °C, and a dramatic increase in ε<inf>rmax</inf> at 1 kHz to a maximum value of 35,000 for the longer anneal. Furthermore, after thermal annealing at 900 °C for 1 week the composition shifted close to the MPB with a great reduction in the transition temperature and a broadening of the dielectric constant maximum. A strong enhancement of the remanent polarization (P<inf>r</inf>) was also observed. © 2006 Elsevier B.V. All rights reserved.
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    Piezoelectric properties of (1 - x)Pb(Zr1/2Ti1/2)O3-xPb(Zn1/3Nb2/3)O3 ceramics prepared by the columbite-(wolframite) precursor method
    (2006-06-01)
    Vittayakorn, N.
    ;
    Puchmark, C.
    ;
    Rujijanagul, G.
    ;
    Tan, X.
    ;
    Cann, D. P.
    Solid solutions of the perovskite structure, (1 - x)Pb(Zr<inf>1/2</inf>Ti<inf>1/2</inf>)O<inf>3</inf>-xPb(Zn<inf>1/3</inf>Nb<inf>2/3</inf>)O<inf>3</inf> with x = 0.1-0.5, were synthesized via the columbite-(wolframite) precursor method. The phase development of calcined powder precursors was analyzed by X-ray diffraction. Phase-pure perovskite of PZN-PZT ceramics was obtained over a wide compositional range. The microstructure and piezoelectric properties were characterrized by means of scanning electron microscopy (SEM), d<inf>33</inf> measurements and impedance analysis. It has been found that ultra-high piezoelectric properties were observed in compositions close to a morphotropic phase boundary (MPB). The maximum value of d<inf>33</inf> (690 pC/N) and the highest k<inf>p</inf> (0.7) were recorded for the composition x = 0.3 located at the boundary between tetragonal and rhombohedral ferroelectric phases. Furthermore, large values of d<inf>33</inf> (600 pC/N) and k<inf>p</inf> (0.67) were observed at a compositions of x = 0.5, which is the boundary between two ferroelectric rhombohedral phases. © 2005 Elsevier B.V. All rights reserved.