Effect of Bi 2O 3 content on physical and optical properties of 15Li 2O–15K 2O– xBi 2O 3–(65− x) B 2O 3: 5V 2O 5 glass system

Abstract

Multi-component bismuth borate glasses doped with vanadium ions 15Li 2O–15K 2O– xBi 2O 3–(65− x) B 2O 3: 5V 2O 5, ( x=3, 5, 7, 10, 12 and 15) have been prepared using conventional melt quench technique. Characterization of the prepared glasses has been done using X-ray diffraction, differential scanning calorimetry and density measurements. The effect of Bi 2O 3 content on the optical properties of the present glass system is studied from the optical absorption spectra recorded in the wavelength range 200–800 nm. The fundamental absorption edge has been identified from the optical absorption spectra. The values of optical band gap for indirect allowed transitions have been determined using available theories. The origin of the Urbach energy is associated with the phonon-assisted indirect transitions. The density and molar volume studies indicate that Bi 2O 3 in these glasses is acting partly as network modifier and partly as network former. The variations in the optical band gap energies, density and molar volume with Bi 2O 3 content have been discussed in terms of changes in the glass structure. Values of the theoretical optical basicity, average crosslink density and the average electronic polarizability are also reported.