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Tri-Valent (Sm3+/ Dy3+) and pentavalent (Nb5+) modified polycrystalline material of Aurivillius family, namely R0.75Bi3.25Ti2.9625.Nb0.03O12 (R = Sm, Dy), were prepared by conventional solid-state reaction method. Impedance and pyroelectric measurements were carried out to understand the electrical properties of the samples. Master plots were drawn to understand the defect role, especially vacancies, and the results were corroborated with the dc-conductivity data. Finally, both the complex impedance spectroscopic as well as pyroelectric results were compared with the impedance data of technological important materials, namely La0.75Bi3.25Ti3O12 (BLT) and lead zirconium titanate (PZT) for the further understanding of defects and its effects at the grain interfaces. [ABSTRACT FROM AUTHOR]

Nano particulate Barium Bismuth Titanate (BaBixTi1-xO3-δ) materials with (x = 0.25, 0.075. 0.125 and 0.175) were prepared through sol-gel chemical route (Pichini method) and the XRD patterns were indexed on the basis of tetragonal-BaTiO3 phase. The electrical impedance measurements were carried out on the samples by using Auto Lab PGSTAT30 impedance analyzer in the frequency region 100 Hz-1 MHz from RT to 500°C. Impedance spectroscopic and complex explicit plots show the presence of both bulk and grain boundary effects, and impedance spectroscopy is shown to be an efficient method capable of detecting the conductivity species and estimating the electrical conductivity as well as activation energy value. Finally, the results are interpreted in terms of the defect dynamics and conduction mechanisms taking place in the samples. [ABSTRACT FROM AUTHOR]

Impedance measurements were made on technological important ferroelectric ceramics, namely PZT and La0.75 Bi3.25Ti3O12 (BLT), in the frequency range of 100 Hz to 1 MHz, from room temperature to 500°C. Combined impedance and modulus spectroscopic analysis along with the detailed conductivity (ac and dc) data was used to understand the heterogeneity of the ceramics and the results were corroborated with temperature coefficient of dc-conductivity (figure of merit) data for the further understanding. AC-conductivity plots against frequency at different temperatures for PZT and BLT suggest the response of obeying Jonscher's and modified Jonscher's law, respectively. [ABSTRACT FROM AUTHOR]

Impedance spectroscopic measurements were carried out on lead based ferroelectric ceramics, namely PZT, PLZT and PMN-PT, in the frequency range of 0.1 Hz-1 MHz. Spectroscopic plots showed broad peaks, and are found to shift towards higher frequency side. Apart from this, both Z'' and M'' spectroscopic peaks are found to coincide almost in the same frequency region. This indicates approximated-Debye behavior. Frequency dependent conductivity plots show two slopes at lower and higher frequency regions. Low frequency relaxations are found to be non-exponential. Bulk relaxation vs. temperature plots are found to obey Arhenius linear fit. The relaxation at lower frequency and higher are attributed to Kohlrausch-Williams-Watt (KWW) type and migration of slow oxygen and lead vacancies. The results are corroborated to the conduction barrier hopping mechanism and new Eyraud's conductivity model. [ABSTRACT FROM AUTHOR]

The Ac conductivity measurements of polycrystalline materials of rare earth substituted Bi[sub 6]Fe[sub 2]Ti[sub 3]O[sub 18] compound at different frequencies (1 kHz-1 MHz) and temperatures (30550°C) are reported. The dc conductivity, ionic hoping rate as well as carrier densities have been extracted from the ac conductivity data. The results show that hoping mechanism dominates at lower temperature. The results are discussed. [ABSTRACT FROM AUTHOR]