Modified Physical, Structural and Optical Properties of Bismuth Silicate Glasses

Iron-containing bismuth silicate glasses with compositions 60SiO2·( ) have been prepared by conventional melt-quenching technique. The amorphous nature of the glass samples has been ascertained by the X-ray diffraction. The density (d) has been measured using Archimedes principle, molar volume ( ) has also been estimated, and both are observed to decrease with the increase in iron content. The glass transition temperature ( ) of these iron bismuth silicate glasses has been determined using differential scanning calorimetry (DSC) technique, and it increases with the increase in content. The IR spectra of these glasses consist mainly of [BiO6], [BiO3], and [SiO4] structural units. The optical properties are measured using UV-VIS spectroscopy. The optical bandgap energy ( ) is observed to decrease with the increase in content, whereas reverse trend is observed for refractive index. 1. Introduction The heavy metal oxide glasses have attracted the attention due to their optoelectronic and photonic applications because of their optical properties such as refractive index, optical nonlinearity, and infrared transmission to develop more efficient lasers and fibre optic amplifiers at longer wavelength than other oxide glasses [1]. Bi2O3, attracted the attention of scientific community which is of current interest because of its important applications in glass ceramics, thermal and mechanical sensors, layers for optical and electronic devices, and so forth and as transmitting windows in the IR region [2–4]. Due to high polarizability and small field strengths of ions, Bi2O3 is not a classical glass former although in the presence of other oxides such as B2O3, PbO, SiO2, and V2O5, it may form a glass network of [BiO3] and [BiO6] pyramids [1, 5]. Silicate glasses, because of their favourable physical, chemical, and optical characteristics, are used in numerous applications: in optics as lenses or beam splitters, in telecommunications as optical fibres, in micro- and optoelectronics, and in near-IR windows due to their low optical attenuation and optical dispersion [6, 7]. Oxide glasses containing transition metal oxides such as Fe2O3 are used in electrochemical, electronic, and electro-optic devices [8]. The presence of transition metal oxides (in addition to Bi2O3) gives new possibilities to extend the properties of these materials. Due to the presence of different valence states of Fe, it participates in glass matrix as and and results in various modified structural units [9]. The addition of Fe2O3 in these glasses enhances the chemical durability and their