Infrared, Raman and XPS spectroscopic studies of Bi2O3–B2O3–Ga2O3 glasses

Glasses with compositions 60Bi2O3–(40−x)B2O3–xGa2O3 (x = 5, 10, 15, 20 mol%) are prepared by conventional melting method. The thermal properties are investigated by differential thermal analysis (DTA) and the structures of the glasses were probed by Infrared, Raman and X-ray photoelectron spectroscopy (XPS). The results show that density, refractive index and optical basicity increase with the increase of Ga2O3. The glass transition temperature (Tg), the onset crystallization temperature (Tx), ΔT (Tx−Tg) decrease with the content of Ga2O3. The cut-off edges in ultraviolet and infrared shift to longer wavelength with the increase of Ga2O3. On the other hand, the addition of Ga2O3 causes a progressive coordination number change of the boron atom from 3 to 4. XPS result indicates both Bi5+ and Bi3+ exist in 5 mol% Ga2O3 content, while Bi5+ amounts decrease with the increase of Ga2O3 contents. The glass is mainly composed of [BiO6], [BO3], [BO4] and [GaO4] polyhedra. Glasses are supposed to have layer structure. [BO3] triangle and [BO4] tetrahedra may be located between the [GaO4] tetrahedral and [BiO6] octahedra to prevent crystallization and to compensate electric charge.