Influence of some thermally resistant transition metal oxides on emission features of Pr3+ ions in zinc borate glasses

Abstract This work consists of studies on the influence of thermally resistant transition metal oxides (TMO) viz., Ta2O5, Nb2O5 and ZrO2 on orange emission and NIR emission (1.3 μm) of Pr3+ ions in zinc borate glasses. Glasses of the composition 40ZnO–2Ta2O5/2Nb2O5/2ZrO2–56B2O3: 2Pr2O3 were synthesized by melt quenching technique. Optical absorption (OA), photoluminescence (PL) emission (in the wavelength region 500–2500 nm at λexc = 443 nm) and decay profiles of the two of the prominent transitions viz., 3P0 → 3H6 and 1G4 → 3H5 of Pr3+ ions were recorded. The spectra were analysed using standard J–O calculations and various radiative parameters associated with prominent transitions were estimated. Intensity of PL bands exhibited substantial increase due to addition of Ta2O5, Nb2O5 and ZrO2 to the host glass. Among the three studied glasses, ZrO2 mixed glasses exhibited the highest luminescence output. All the radiative parameters including quantum efficiency are observed to be the largest for ZrO2 mixed glasses. The results of IR spectral studies were also used for the analysis of emission spectra. The analysis indicated the degree of structural variations in the vicinity of luminescent Pr3+ ions is different due to addition of different transition metal oxides and such variations are found to be responsible for the changes in the PL output. Since a substantial improvement of PL emission corresponding to 1G4 → 3H5 transition is observed due to the admixing of TMOs, these glasses may be considered as the favourable candidates for the applications in telecommunications. Additionally, the emission in the green spectral region (which is predicted to be feeble under normal conditions) in the PL spectrum of Pr3+ ions is also found to be considerably increased and it is attributed to the transfer of energy from ZnO to Pr3+ ions in this region.