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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]

Glasses of various compositions in the system (100 - x )Li 2 B 4 O 7 - x (SrO-Bi 2 O 3 -Nb 2 O 5 ) (10 ≤ x ≤ 60) (in molar ratio) were prepared via a conventional melt-quenching technique. The glassy nature of the as-quenched samples was established by Differential Thermal Analyses (DTA). X-ray powder diffraction (XRD) and Transmission Electron Microscopic (TEM) studies confirmed the amorphous nature of the as quenched and crystallinity in the heat-treated samples. The formation of nanocrystalline layered perovskite SrBi 2 Nb 2 O 9 (SBN) phase, in the samples heat-treated at temperatures higher than 550°C, through an intermediate fluorite phase in the LBO glass matrix was confirmed by both the XRD and High Resolution Transmission Electron Microscopy (HRTEM). The samples that were heat-treated at two different temperatures, 550 and 625°C, (containing 0.35 and 0.47 μm sized SBN crystallites) exhibited broad dielectric anomalies in the vicinity of ferroelectric to paraelectric transition temperature of the parent SBN ceramics. A downward shift in the phase transition temperature was observed with decreasing crystallite size of SBN. The observation of pyroelectric and ferroelectric properties for the present samples confirmed their polar nature. [ABSTRACT FROM AUTHOR]

Samarium modified SrBi4-xSmxTi4O15 (x = 0, 0.13, 0.43 and 0.78) ferroelectric ceramics of Aurivillius family were prepared by conventional solid state reaction method. X-ray diffraction studies confirm the formation of a single-phase. Microstructural images show randomly oriented palate-like structure. Broad dielectric peaks were found to obey the modified Curie-Weiss law. The overall inherent ferroelectric nature was explained on the basis of the Avrami model. Furthermore, with increasing the Sm3+ content, the grain morphology and diffusive parameters have shown a comprehending impact on the ferroelectric (hysteresis) behavior. [ABSTRACT FROM AUTHOR]