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Oxygen-deficient and charge- imbalanced polycrystalline materials of three-layered Auruvillius compound, namely Sr2Bi2Nb3O12(SBN), was synthesized by Sol-Gel method. X-ray diffraction analysis was made on SBN and lattice parameters were calculated. Electrical impedance and Pyroelectric measurements were performed on SBN. The broad peak observed in the dielectric permitivity data indicates that the transition is diffused phase transition (DPT) and the modified Curie-Weiss law was used to describe the DPT of SBN. The sharp intensity peak observed at 176 and 219 cm−1in Raman spectra is an indicative of Sr-O-Sr and Sr-O-Bi bonds and its competitive interactions. The peaks of FTIR spectra appeared at 610 cm−1confirmed the same. The nature of difffused type was attributed to compositional heterogenity and the results were corroborated with the log-log spectroscopic plots of impedance,modulus and permitivity for better understanding of the disorder ferroelectric behavior of the sample. The broad semicircle behavior observed in the complex impedance aswell as modulus plot, associated with grain and grain boundary, confirm the same. [ABSTRACT FROM AUTHOR]

Novel polycrystalline materials of bismuth substituted barium titanate, namely, BaBixTi1-xO3-δ, (x = 0.025, 0.075, 0.125 and 0.175) was prepared by sol-gel chemical route and characterized by X-ray diffraction and scanning electron microscopy. Bismuth ion was added in place of titanium of B-site of ABO3 perovskite structure and both the site-balance as well as charge-balance was considered. The substitution of bismuth for Ti-site is clearly seen in both the XRD as well as IR spectroscopic data. Dielectric and impedance analysis were also made on the present novel ceramics. The above mentioned substitution involves ionic compensation, through creation of cation vacancies and is explained by proposing the defect dynamics. The results were corroborated with dielectric and complex impedance analysis for further understanding of ionic motion in this kind of disordered diffused materials. [ABSTRACT FROM AUTHOR]

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]

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]