Structural, optical and dielectric properties of glass-nanocomposite

Transparent glass-nanocomposite sample [50Li2B4O7–50(SrO–Bi2O3–Nb2O5)] (mol %) was prepared by a conventional melt-quenching technique. Fluorite (Bi3NbO7) and SrBi2Nb2O9 (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 Li2B4O7 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.

Research Highlights
► Nanocrystallization fluorite (Bi3NbO7) and SrBi2Nb2O9 embedded in a 50% Li2B4O7 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 Li2B4O7 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.