Structural, dielectric and optical properties of lithium borate-bismuth tungstate glass-ceramics
Glasses in the system (1 {minus} x)Li{sub 2}B{sub 4}O{sub 7}-xBi{sub 2}WO{sub 6} (0.1 {le} x {le} 0.35) were prepared by spat quenching technique. Powder X-ray diffraction (XRD) and differential thermal analysis (DTA) were employed to characterize the as-quenched glasses. High-resolution transmission electron microscopy (HR-TEM) revealed the presence of fine, nearly spherical crystallites of Bi{sub 2}WO{sub 6} varying from 1.5 to 20 nm in size, depending on x in the as-quenched glasses. The glasses (corresponding to x = 0.3) heat-treated at 723 K for 6 h gave rise to a clear crystalline phase of Bi{sub 2}WO{sub 6} embedded in the Li{sub 2}B{sub 4}O{sub 7} glass matrix, as observed by X-ray studies. The dielectric constants of the as-quenched glasses as well as the glass-ceramics decreased with increase in frequency (40Hz--100 kHz) at 300 K, and the value obtained for the glass-ceramic (x = 0.2) is in agreement with the values predicted using Maxwell's model and the logarithmic mixture rule. The dielectric constants for both the as-quenched glass and the glass-ceramic increased with increase in temperature (300--873 K) and exhibited anomalies close to the onset of the crystallization temperature of the host glass matrix. The optical transmission properties of these glass-ceramics were found to be compositional dependant.
- Research Organization:
- Indian Inst. of Science, Bangalore (IN)
- OSTI ID:
- 20075659
- Journal Information:
- Materials Research Bulletin, Vol. 34, Issue 14-15; Other Information: PBD: Nov-Dec 1999; ISSN 0025-5408
- Country of Publication:
- United States
- Language:
- English
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