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

The glasses with composition 75TeO(2)-10ZnO-(15-x)Nb2O5-xNd(2)O(3) (0 <= x <= 9 mol%) were prepared using melt quenching method and their physical properties such as density (rho), molar volume (V-M), average crosslink density ((n(c)) over bar), oxygen packing density (OPD) and number of bonds per unit volume (rib) 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 (T-g) crystallization onset (T-o) and thermal stability (Delta T) 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 run which are assigned to the transition of electrons from (ground State) I-4(9/2) -> G(11/2) : I-4(9/2) -> K-2(3/2), (2)G(7/2) : I-4(9/2) -> (4)G(5/2), (4)G(7/2) : I-4(9/2) -> S-4(3/2): F-4(7/2) -> H-2(9/2), F-4(5/2) and I-4(9/2) -> F-2(3/2) respectively. From optical absorption data the energy band gap (E-opt) and Urbach energy (Delta E) were calculated. (C) 2012 Elsevier B.V. All rights reserved.