Physical, optical and luminescence properties of B₂O₃-SiO₂-Y₂O₃-CaO glasses with Sm³⁺ions for visible laser applications

Silicoborate glasses with composition of (BSYCaSm:(55-x)B₂O₃+ 10SiO₂ +25Y₂O₃ +10CaO + xSm₂O₃), (where, x= 0.05, 0.10, 0.20, 0.25, 0.30, 0.40, 0.50, mol%) have been synthesized by using the well-known melt quenching technique. The present work deals with physical, optical, photoluminescence, X-ray luminescence and decay time studies of silicoborate glasses. Judd-Ofelt (JO) intensity parameters (Ω₂, Ω₄ and Ω₆) and radiative properties for the important luminescent level of Sm³⁺ ions were derived by using the absorption spectrum of 0.3 mol% Sm₂O₃ doped glass. The luminescence spectra in the visible region was obtained due to ⁴G_5/2 → ⁶H_J (5/2, 7/2, 9/2 and 11/2) transition of Sm³⁺ ion under 401 nm excitation. The decay profile for the ⁴G_5/2 level of Sm³⁺ ions was analyzed and found that for lower concentration (≤ 0.20 mol%) it is single exponential in nature whereas for higher concentration (≥ 0.25 mol%), it turns in to non-exponential due to the transfer of energy between donor (excited state Sm³⁺ion) and acceptor (ground state Sm³⁺ ion). As the concentration of Sm³⁺ ions increases the decay time of ⁴G_5/2 state decreases. The well-known Inokuti-Hirayama (IH) model was used for fitting the non-exponential decay curves where S = 6 indicates that energy transfer process is of dipole-dipole type. Hence, in the present work, intense transition of ⁴G_5/2 → ⁶H_7/2 (601 nm) is found to be suitable for reddish-orange laser emission. CIE chromaticity diagram has been performed for verifying the results of fluorescence in visible laser applications at 601 nm.