1. Evolution of Ferroelectric SrBi 2 Nb 2 O 9 Phase in the Li 2 B 4 O 7 -SrO-Bi 2 O 3 -Nb 2 O 5 Glass System.
- Author
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Prasad, N. Syam, Subbanna, G. N., and Varma, K. B. R.
- Subjects
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FERROELECTRICITY , *PEROVSKITE , *THERMAL analysis , *X-ray diffraction , *TRANSMISSION electron microscopy , *DIELECTRICS - Abstract
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]
- Published
- 2002
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