Band gap and polarizability of boro-tellurite glass: Influence of erbium ions

Understanding the influence of rare earth ions in improving the structural and optical properties of inorganic glasses are the key issues. Er3+-doped zinc boro-tellurite glasses with composition 30B(2)O(3)-10ZnO(60-x) TeO2-xEr(2)O(3) are prepared (x = 0, 0.5, 1, 1.5 and 2 mol%) using melt quenching technique. The physical and optical characterizations are measured by density and UV-Vis-IR absorption spectroscopy. The color of the glass changed from light yellow to deep pink due to the introduction of Er3+ ions. The maximum density is found to be -4.73 g cm(-3) for 1 mol% of Er-(3+) doping. The variations in the polarizability (6.7-6.8 cm(3)) and the molar volume (27.987-28.827 cm3 moll) with dopant concentration are ascribed to the formation of non-bridging oxygen. This observation is consistent with the alteration of number of bonds per unit volume. The direct and indirect optical band gaps are increased while the phonon cut-off wavelength and Urbach energy decreased with the increase of erbium content. A high density and wide transparency range in VIS-IR area are achieved. Our results on high refractive index (-2.416) and polarizability suggest that these glasses are potential for photonics, solid state lasers and communications devices. (C) 2014 Elsevier B.V. All rights reserved.