The Study on the Decolorization and Properties of Bismuth Glass

Abstract

PbO glass has an adverse effect on the environment; the bismuth glass has a high refractive index, low melting temperature, softening temperature, and glass transition temperature (T_g), so that it can be used as a lead-free glass, used in optoelectronics, electronics, optics, and other components, which bismuth glass has been proved to be an important replacement material. Due to the higher melting temperature, Bi³⁺ ions tend to partially reduce to the low valence state of Bi⁰, which in turn causes coloration of the glass. In this experiment, the absorption peaks of glass oxidized brown color were observed at about 470 nm at 1,100°C (Bi₂O₃ = 40, 45 mol%) and 1,000°C (Bi₂O₃ = 40 mol%) for these three curves. The bismuth glass produced by high-temperature melting is not suitable for optical applications; by adding an oxidant (Sb₂O₃), which inhibits the reduction reaction of bismuth ions and maintains the ions in the state of Bi³⁺, the glass becomes more transparent in appearance and the transmittance is also improved and raised to approximately 75%–80%, which proves that appropriate additives are sufficient to greatly improve the application of bismuth glass for optical components. In the research process, the density and molar volume were measured by Archimedes method, Raman analysis was used to explore the influence of its structural changes, UV/Vis spectroscopy was used to measure the transmittance and absorption spectra for analysis and discussion, and TMA was used to observe the thermal properties, in the hope of developing a good optical properties of the glass, and the present experiments have confirmed that the addition of a small amount of Sb₂O₃ changes the color of the glass from black to a light yellow, which can be better used in the optical glass.