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Impedance study of giant dielectric permittivity in BaFe0.5Nb0.5O3 perovskite ceramice
Uraiwan Intatha,Sukum Eitssayeam,John Wang,Tawee Tunkasiri 한국물리학회 2010 Current Applied Physics Vol.10 No.1
Single-phase BaFe0.5Nb0.5O3 (BFN) ceramics were prepared by solid-state reaction method and were characterized by X-ray Diffraction (XRD) technique. Then, impedance spectroscopy measurements were conducted in a frequency range from 100 Hz to 1 MHz and in a temperature range from 293 to 600 K. Relaxation phenomena of non-Debye type have been observed in the BFN ceramics, as confirmed by the Cole–Cole plots. The higher values of e0 at the lower frequencies are explained on the basis of the Maxwell–Wagner (MW) polarization model. Complex impedance analysis enables us to separate the contributions from grains and grain boundaries of our samples. We found that at higher temperatures grain boundary resistance is higher than grain resistance, irrespective of composition.
Sukum Eitssayeam,Uraiwan Intatha,Kamonpan Pengpat,Gobwute Rujijanagul,Kenneth J.D. MacKenzie,Tawee Tunkasiri 한국물리학회 2008 Current Applied Physics Vol.8 No.3,4
Relaxor ferroelectrics with A'A"(B'B")O₃- type perovskite structures have attracted much attention because of their excellent dielec-tric and electromechanical properties. The physical properties or device parameters of PZT can be tailored by improved synthesis andprocessing techniques and by making suitable substitutions into the A and/or B sites. In this study, Pb0.84Ba0.16(Zr0.44Ti0.40-Fe0.08Nb 0.08)O₃ ceramics were prepared by solid state reaction and the eect of the processing parameters on the ferroelectric, dielectricand pyroelectric properties was determined. Optimal dielectric properties were achieved in Pb0.84Ba0.16(Zr0.44Ti0.40Fe0.08Nb 0.08)O₃ ceramics by calcination at 1100.C and sintering at 1250℃. Hysteresis loop measurements of these materials indicated a remanent polarization(Pr) and spontaneous polarization (Ps) of 15.88 μC/cm² and 26.29 μC/cm², respectively. TEM micrographs showed nano-domains in thecalcined powder conrming their ferroelectric properties. The dielectric properties also show ferroelectric behavior, with a Curie temper-ature of approximately 220℃. The values ofpi show a continuous increase with increasing temperature up to a maximum value. 800 nC/cm² K at~120℃.
Dielectric and impedance measurements on (1-x)Ba(Fe1/2Ta1/2) O3-xBa(Zn1/3Ta2/3)O3 ceramics
Thanatep Phatungthane,Gobwute Rujijanagul,Kamonpan Pengpat,Sukum Eitssayeam,Tawee Tunkasiri,Luiz F. Cotica,Ruyan Guo,Amar S. Bhalla 한국물리학회 2014 Current Applied Physics Vol.14 No.12
In this work, ((1x)Ba(Fe1/2Ta1/2)O3-xBa(Zn1/3Ta2/3)O3), ((1x)BFT-xBZT) ceramics with x ¼ 0.00e0.12 were synthesized by the solidestate reaction method. X-ray diffraction data revealed that both the powders and ceramics were of a pure-phase cubic perovskite structure. All ceramics showed large dielectric constants. For the x ¼ 0.12 sample, a very high dielectric constant (>20,600) was observed. A lowering in the dielectric loss compared to pure BFT ceramics was observed with the BZT addition. The impedance measurements indicated that BZT has a strong effect on the bulk grain and grain boundary resistance of BFT ceramics. These results are in agreement with the measured dielectric properties. Based on dielectric and impedance results, (1x)BFT-xBZT ceramics could be of great interest for high performance dielectric materials applications due their giant dielectric constant behavior.