Structural and luminescence properties of transparent borate glass co-doped with Gd3+/Pr3+ for photonics application

A new glass system of lithium borate doped with Gd2O3 and Pr2O3 has been fabricated using a conventional melt quenching technique. The physical parameters, such as density, molar volume, and refractive index, were measured and found to increase as the concentrations of lanthanide oxide (Gd2O3 and Pr2O3) in the glass increased, revealing the underlying structural changes. According to the results of XRD and FTIR, the synthesized glasses exhibited an amorphous structure, and borate complexes served as the triangular BO3, tetrahedral BO4, and OH group amounts in oxide glass. The photoluminescence (PL) spectra show characteristic emission bands resulting from f-f transitions of Pr3+ ions. The strongest emission occurred at 603 nm, corresponding to the transition from the 1D2 state to the 3H4 state. The optimal concentration of Gd2O3 for maximizing emission intensity was found to be 5.0 mol%, and this concentration will be used in the next experiment with varying Pr2O3 concentrations. In the subsequent experiment, emission spectra were recorded by exciting the glass with light at wavelengths of 445 nm, 469 nm, and 483 nm. The resulting emission spectra displayed the characteristic pattern associated with the emission of Pr3+. This emission peak at 603 nm represented the strongest intensity in the spectra, which is a common characteristic of Pr3+ emission. The emission intensity of the glasses initially increases with increasing concentrations of Pr2O3 up to 0.3 mol%, but beyond this concentration, the emission intensity starts to decrease. This behavior indicates the occurrence of a quenching effect at the 0.3 mol% concentration of Pr2O3. X-ray absorption near-edge structure (XANES) analysis confirmed that praseodymium ions were predominantly in the 3 + oxidation state. The chemical composition of the created glass was confirmed to be suitable for photonics applications.