Concentration dependent luminescence quenching of Er3+-doped zinc boro-tellurite glass

Understanding the mechanism of luminescence quenching in rare earth doped tellurite glass is an important issue. The Er3+-doped boro-tellurite glasses with compositions 30B(2)O(3)+10ZnO+(60-x)TeO2+xEr(2)O(3) (where x=0, 0.5, 1, 1.5 and 2 mol%) were prepared by melt quenching method. Structural and optical properties of the proposed glasses were characterized using XRD, FTIR, density, UV-vis-IR absorption and PL spectroscopy. The amorphous nature of these glasses was confirmed by XRD technique. The IR-spectrum reveals five absorption bands assigned to different B-O and Te-O vibrational groups. UV-vis-IR absorption spectrum exhibits seven absorption bands at 6553, 10,244, 12,547, 15,360, 19,230, 20,661 and 22,522 cm(-1) corresponding to I-4(13/2), I-4(11/2), I-4(9/2), F-4(9/2), H-2(11/2), F-4(7/2) and F-4(3/2) excited states of Er3+ ion respectively. The optical band gap energy (E-opt) corresponding to the direct and indirect allowed transitions decreased, while the Urbach energy and cut-off wavelengths are increased by the introduction of Er3+ ions. The refractive index, density and phonon cut-off edge of the samples are increased and the molar volume decreased with the further addition of dopants. The Judd-Ofelt parameter (Omega(2)) decreased from 5.73 to 3.13 x 10(-20) cm(2) with the increase of erbium ions concentration from 0.5 to 2 mol%. The PL spectra show green emissions for the transition from H-2(11/2) and S-4(3/2) excited states to I-4(15/2) ground state, which show strong quenching due to the addition of Er3+ ions. (C) 2013 Elsevier B.V. All rights reserved.