Raman spectroscopy, thermal and optical properties of TeO2–ZnO–Nb2O5–Nd2O3 glasses

The glasses with composition 75TeO2–10ZnO–(15−x)Nb2O5–xNd2O3 (0 ≤ x ≤ 9 mol%) were prepared using melt quenching method and their physical properties such as density (ρ), molar volume (VM), average crosslink density (nc¯), oxygen packing density (OPD) and number of bonds per unit volume (nb) were determined. Raman spectroscopic studies showed that the glass network consists of TeO4, TeO3+1, TeO3 and NbO6 units as basic structural units. The glass transition temperature (Tg), crystallization onset (To) and thermal stability (ΔT) were determined from DSC thermograms. The Raman and DSC results were found to be correlated with the physical properties. In the optical absorption spectra six absorption bands were observed with different relative intensities at around 464, 522, 576, 742, 801 and 871 nm which are assigned to the transition of electrons from (ground state) 4I9/2 → G11/2; 4I9/2 → 2K3/2, 2G7/2; 4I9/2 → 4G5/2, 4G7/2; 4I9/2 → 4S3/2; 4F7/2 → 2H9/2, 4F5/2 and 4I9/2 → 2F3/2 respectively. From optical absorption data the energy band gap (Eopt) and Urbach energy (ΔE) were calculated.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The present glasses were prepared by melt quenching method. ► The Raman spectra confirmed the presence of TeO3, TeO4 and NbO6 units in the glass network. ► The present glasses show the high thermal stability and are more useful for drawing of optical fibres. ► Optical band gap (Eopt) values increase with the increase of Nd2O3 content.