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Effect of barium substitution on phase transitions of lead barium zirconate ceramics prepared by solid state reaction method
(2007-12-01)
Rujijanagul, Gobwute
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Vittayakorn, Naratip
;
Bongkarn, Theerachai
The effect of Ba2+ substitution on the phase transitions of (Pb<inf>1-x</inf>Ba<inf>x</inf>)ZrO<inf>3</inf> (PBZ) ceramics (0.0≤x≤0.30) has been investigated as a function of x. Phase formation and phase transition of PBZ were investigated by x-ray diffraction (XRD) and thermal analysis, respectively. It was found that the structure of sintered pellets is orthorhombic for 0.0≤x≤0.10 and rhombohedral for 0.20≤x≤0.30, whereas orthorhombic and rhombohedral phases coexist at x = 0.15. The proportion of ferroelectric and paraelectric phase in the samples gradually decreased with increasing Ba2+ content.
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Observation of high dielectric constants in x (Pb (Zn13 Nb23) O3 - (0.2-x) Pb (Ni13 Nb23) O3 -0.8Pb (Zr12 Ti12) O3 ternary solid solutions
(2007-11-23)
Nabunmee, Sucheewan
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Rujijanagul, Gobwute
;
Vittayakorn, Naratip
;
Cann, David P.
In the present work, we demonstrate the results of combining two excellent ferroelectric materials at their morphotropic phase boundary compositions, i.e., 0.2 (Pb (Zn13 Nb23) O3 -0.8Pb (Zr12 Ti12) O3 (0.2PZN-0.8PZT) and 0.2Pb (Ni13 Nb23) O3 -0.8Pb (Zr12 Ti12) O3 (0.2PNN-0.8PZT) to form a ternary solid solution of x (Pb (Zn13 Nb23) O3 - (0.2-x) Pb (Ni13 Nb23) O3 -0.8Pb (Zr12 Ti12) O3 (xPZN- (0.2-x) PNN-0.8PZT) which exhibits superior dielectric properties. Examination of the dielectric spectra indicated that the ternary system exhibits a very high relative permittivity of 49 800 (at 10 kHz) for the composition at x=0.10. In addition, an increased amount of PZN was observed to enhance the ferroelectric properties of the system. © 2007 American Institute of Physics.
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The effect of post-sintering annealing induced extrinsic dielectric properties in PZT-PZN ceramics
(2007-08-02)
Vittayakorn, Naratip
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Cann, David P.
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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
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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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The improvement in dielectric and ferroelectric performance of PZT-PZN ceramics by thermal treatment
(2007-07-01)
Vittayakorn, Naratip
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Rujijanagul, Gobwute
;
Cann, David P.
Pyrochlore-free lead zirconate titanate - lead zinc niobate ceramics have been systematically investigated in the as-sintered condition as well as after annealing. The ceramics were characterized by dielectric spectroscopy and Sawyer-Tower polarization (P-E) measurements. The powders of Pb[(Zr<inf>1/2</inf>Ti<inf>1/2</inf>)<inf>(1-x)</inf>-(Zn<inf>1/3</inf>Nb<inf>2/3</inf>)<inf>x</inf>]O<inf>3</inf>, where x = 0.1, 0.3 and 0.5 were prepared using the columbite-(wolframite) precursor method. The general trend seems to indicate that the annealed samples become more normal-ferroelectric-like behavior as opposed to the relaxor-ferroelectric-like behavior observed in the as-sintered state. The as-sintered 0.9PZT-0.1PZN ceramic exhibited weak relaxor-ferroelectric behavior, with a relatively low dielectric constant maximum of 14,000 measured at 1 kHz. Annealing resulted in a transition to normal-ferroelectric-like behavior, a shift in the dielectric maximum temperature from 360 °C to 350 °C, and a dramatic increase in the dielectric constant at 1 kHz to a maximum value of 35,000 for the longer anneal. After thermal annealing at 900 °C for one week a strong enhancement of remanent polarization (P<inf>r</inf>) was observed. © 2007 Elsevier B.V. All rights reserved.
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Phase transition, mechanical, dielectric and piezoelectric properties of perovskite (Pb1-xBax)ZrO3 ceramics
(2007-01-01)
Vittayakorn, Naratip
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Bongkarn, Theerachai
;
Rujijanagul, Gobwute
(Pb<inf>1-x</inf>Ba<inf>x</inf>)ZrO<inf>3</inf> ceramics were prepared in the composition range 0.00≤x≤0.30 by the mixed oxide solid-state reaction method. The samples were kept at the calcination temperature 1000 °C for 1 h and at the sintering temperature 1300 °C for 3 h. The structural phase transitions and the dielectric properties were studied. It was found that the density of the ceramics decreases with increasing amount of Ba2+, whilst the average grain size is in the range 1-2.3 μm. The structure of as-calcined powder reveals that the fraction of the orthorhombic phase is decreasing with increasing Ba2+ content. The values of Vickers and Knoop hardness are in the range of 4.10-6.48 and 4.15-5.67 GPa, respectively. Dielectric measurements show that the antiferroelectric phase (AFE)-ferroelectric phase (FE) and the FE to paraelectric phase (PE) phase transformation temperatures decrease with increasing Ba2+ concentration. The AFE-FE phase transformation is detected for compositions 0.00≤x≤0.075. The maximum dielectric constant gradually increases with increasing composition up to x=0.20. For higher Ba2+ concentrations, the lowering of the maximum dielectric value is accompanied by a progressive broadening of the permittivity peak. The d<inf>33</inf> values of the samples increase from ∼0 to 87 pC/N with increasing Ba2+ concentration from x=0.00 to 0.30. © 2006 Elsevier B.V. All rights reserved.
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Dielectric and ferroelectric characteristics of 0.7PZT-0.3PZN ceramics substituted with Sr
(2005-08-21)
Vittayakorn, Naratip
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Uttiya, Sureeporn
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Rujijanagul, Gobwute
;
Cann, David P.
Lead zirconate titanate-lead zinc niobate (PZT-PZN) ceramics with compositions close to the morphotropic phase boundary were investigated as a function of Sr doping. The powders were prepared using the columbite- (wolframite) precursor method. Dielectric and ferroelectric properties of the as-sintered and annealed samples were measured. The results showed that with increasing Sr concentration dielectric constant versus temperature curves become gradually broader. Sr doping has been shown to produce a linear reduction in the transition temperature (T<inf>m</inf>) (294.1-12.7x °C) with concentration (x). The maximum value of the dielectric constant decreased and the degree of diffuse phase transition was enhanced with Sr doping. However, the results indicated that the degree of disorder in Sr-modified PZT-PZN was further improved by thermal annealing. After thermal annealing at 900°C for 48 h a strong enhancement of dielectric constant (ε<inf>r</inf>) and remanent polarization (P<inf>r</inf>) was observed. © 2005 IOP Publishing Ltd.

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