Effect of excitation and doping concentration on the emission color of a fluorophosphate glass doped with Tb3+ and Eu3+

We report in this work on the optical properties of a fluorophosphate glass system having the starting composition [60 (NaH2PO3, H2O) + 15 ZnO + 15 BaF2 + 10 WO3] prepared by the conventional melt-quenching procedure and doped with different concentrations of Tb3+ and Eu3+ ions. The XRD diffraction pattern has proved the amorphous nature of this glass system. The analysis of the optical spectra showed that Tb3+ ions may be excited by UV or blue light directly or through energy transfer from tungsten species, whereas Eu3+ ions may be excited by UV or blue radiations through charge transfer bands or sensitization by Tb3+ ions. We have shown that we can tune the color of the emitted light by changing either the doping concentration or the excitation wavelength. We have also seen that it is possible to tune the color of the emitted light by the same glass sample just by varying the excitation power, which is more convenient than modifying the doping concentration or the excitation wavelength and it may be important for the conception of solid-state lighting source.