Structural characterization, Gd3+ → Eu3+ energy transfer and radiative properties of Gd/Eu in codoped Li2O–ZnO–SrO–B2O3–P2O5 glass

A series of Gd doped Li2O–ZnO–SrO–B2O3–P2O5 glasses and co-doped samples with different Eu3+ concentrations was synthesized through the conventional melt quenching route. The structural, morphological, and elemental distributions were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive X-ray analysis. The effect of Gd doping on the thermal properties of prepared glasses was studied by differential thermal analysis. Characteristics photoluminescence (PL) emissions of Gd3+ (6P7/2→8SJ/2) and Eu3+ (5D0→7FJ) were observed in the doped glass matrix. Strong PL emissions at 312 nm (6P7/2 → 8S7/2) shown by the Gd-doped glasses upon excitation at 274 nm suggests its prospect in phototherapy applications. Phonon energy of the glass matrix calculated from the phonon sidebands of Eu3+ spectra was obtained as 970 cm−1. The values of branching ratios and stimulated emission cross-sections obtained from Judd-Ofelt analysis indicate the suitability of the prepared Gd–Eu co-doped glasses for optical display devices. The Observed Ω2 > Ω4 suggests Eu3+ occupancy preferably at less centrosymmetric sites in the studied glass hosts. The change in the local symmetry environment of the dopant ions with Gd incorporation was further analyzed by determining the asymmetry ratio of Eu3+ emission in the co-doped glass. The emission spectra and luminescence lifetimes suggested the efficient energy transfer from Gd3+ to Eu3+. Co-doping of Gd led to better chromaticity values and improved color purity of Eu3+ red emission.