NIR and upconversion luminescence properties of Nd3+doped in Gd2O3-CaO-SiO2-B2O3 glass system

In this work, properties of Nd³⁺ in Gd₂O₃-CaO-SiO₂-B₂O₃ glass systems with composition 25Gd₂O₃-10CaO-10SiO₂-(55-x)B₂O₃-xNd₂O₃ where x = 0.0, 0.5, 1.0, 1.5, 2.0 and 2.5 mol% were investigated. The optical absorption spectra show peaks at ⁴F_3/2 (877 nm), ⁴F_5/2+²H_9/2 (802 nm), ⁴F^7/2+⁴S^3/2 (743 nm), ⁴F_9/2 (682 nm), ²H_11/2 (627 nm), ²G_7/2 +⁴G_5/2 (582 nm), ⁴G_7/2 +²K_13/2 (527 nm), ⁴G_11/2 (481 nm), ²P_1/2 (427 nm) and ²L_15/2 + ⁴D_1/2 + ¹I1_1/2+ ⁴D_5/2+ ⁴D_3/2 (355 nm) reflecting the Nd³⁺ ions in glass matrices. The densities were increased with increasing of Nd₂O₃ concentration. This indicates the increase of the molecular weight by the replacement of B₂O₃ with a heavier Nd₂O₃ oxide in the glass. The upconversion luminescence spectra show bands at 393 nm for all Nd₂O₃ concentration and the strongest intensity from 2.5% mol of Nd₂O₃ was obtained. For NIR luminescence, the intensity of Nd³⁺ emission spectra increases with increasing concentrations of Nd³⁺ up to 1.5 mol% and beyond 1.5 mol% the concentration quenching is observed.