Concentration dependent Eu3+ doped boro-tellurite glasses—Structural and optical investigations

Eu3+ doped boro-tellurite glasses with the chemical composition (40−x)B2O3+30TeO2+15MgO+15K2O+xEu2O3 (where x=0.01, 0.1, 1, 2 and 3 wt%) have been prepared by following the conventional melt quenching technique. Structural and optical behavior of the prepared Eu3+ doped boro-tellurite glasses were studied and compared with reported literature. The XRD pattern confirms the amorphous nature and the FTIR spectral studies explore the presence of BO stretching vibrations, O3BOBO3 bond bending vibrations along with the bending vibration of TeOTe linkages in the prepared glasses. Through the optical absorption spectra, bonding parameters (image) were calculated to identify the ionic/covalent nature of the glasses. Judd–Ofelt (JO) parameters have been calculated from the luminescence spectral measurements. The JO parameters (Ωλ, λ=2, 4 and 6) were used to calculate the radiative properties like transition probability (A), stimulated emission cross-section (image), radiative lifetime (τrad), and branching ratios (βR) for the 5D0→7FJ (J=0, 1, 2, 3 and 4) emission transitions of the Eu3+ ions. The local site symmetry around the Eu3+ ions were calculated through the luminescence intensity ratio (R) of the 5D0→7F2 to 5D0→7F1 transitions. The experimental lifetime of the 5D0 level in the Eu3+ doped boro-tellurite glasses has also been calculated and compared with similar Eu3+ glasses. The lifetime of the 5D0 level is found to be less than the reported glasses and it may be due to the presence of OH− groups in the prepared glasses. The Optical band gap (Eopt), band tailing parameter (B) and the Urbach energy (ΔE) values of the prepared glasses were calculated from the absorption spectral measurements and the results were discussed and reported.