Structural, optical and dielectric properties of glass-nanocomposite

Transparent glass-nanocomposite sample [50Li 2B 4O 7–50(SrO–Bi 2O 3–Nb 2O 5)] (mol %) was prepared by a conventional melt-quenching technique. Fluorite (Bi 3NbO 7) and SrBi 2Nb 2O 9 (SBN) was produced by heat-treating the as-prepared sample at 773 K for 6 h (HT773). The nanocrystallites of fluorite and SBN phases in the Li 2B 4O 7 glass matrix were established by differential thermal analysis (DTA) which is confirmed by X-ray powder diffraction (XRD), infrared spectroscopy and transmission electron microscopic (TEM) studies. The influence of heat-treating the as-prepared sample on the optical properties (transmission, optical band gap and Urbach energy) has been investigated. Properties such as dielectric constant and dielectric loss as a function of frequency (120 Hz –100 k Hz) and temperature (300–829 K) are reported. ► Nanocrystallization fluorite (Bi 3NbO 7) and SrBi 2Nb 2O 9 embedded in a 50% Li 2B 4O 7 glass matrix were prepared by heat-treated. ► DTA analysis of HT773 showed the presence of nanocrystallites of fluorite and SBN phases in the glass matrix Li 2B 4O 7 which confirmed by X-ray, infrared spectroscopy and TEM studies. ► Optical studies indicated the reduced optical band gap in HT773. ► Dielectric studies showed that the lithium ion conduction in HT773 is hindered due to the presence of fluorite and SBN. ► The heat-treated sample exhibited broad dielectric anomalies in the vicinity of the ferroelectric-to-paraelectric transition temperature of the SBN phase.