Niobium oxide influence in the phosphate glasses triply doped with Er3+/Yb3+/Eu3+ prepared by the melting process

This work reports on the preparation and photoluminescence properties of the phosphate glass matrix based on P2O5-Al2O5-Na2O-K2O (PANK) doped with Yb3+, Eu3+ and Er3+ with different amount of Nb2O5 prepared by the conventional melting process. The Raman bands assigned to the Nb2O5 indicating the insertion of this oxide in the glass. Under UV excitation, the emission spectra presented narrow bands assigned to the Eu3+, arising from the 5D0→7FJ (J = 0, 1, 2, 3 and 4). It was observed that the materials have at least two lifetimes values of the Eu3+ ion. In all materials, it was observed that the amount of Nb2O5 does not influence the photo-luminescent properties of the Eu3+ ion, providing potential applications in energy conversion. The optical properties like refractive index, optical basicity, optical electronegativity, Urbach Energy, direct and indirect band-gap, Judd-Ofelt parameters were calculated and the covalence bonding of Eu3+ with the neighbors ligands was evaluated as a function of Nb2O5 concentration. Co-doping with Er3+/Yb3+ promotes the emission in the infrared region, with a maximum around 1535 nm and bandwidth of 28 nm under 980 nm pumping.