Effect of samarium oxide addition on the structural, thermal, and optical properties and photoluminescence of lithium borate glass

The samples were prepared in compliance with the form 33 Li₂O–66 B₂O₃—(1-x) AgF—x Sm₂O₃, where x = 0, 0.25, 0.5, and 0.75. Powdered samples were converted to a glassy state via melting and quenching. The glassiness of the prepared samples was examined using X-ray diffraction (XRD) and Differential Thermal Analysis (DTA). From the absorption spectra of the prepared glass samples, the band gap in the optical spectrum changed slightly in the range of 3.45, whereas the Urbach energy decreased from 0.32 to 0.267 eV. The fluctuations of the optical band gap and Urbach energy can be attributed to variations in the glass structure. Sm3 + emitted intense reddish-orange light under blue and UV light excitation. There are six excitation bands in the Sm³⁺ excitation spectrum situated in the blue and UV regions, peaking at 361.7, 374, 400, 417, 462, and 475 nm, which are attributed to the transitions from ⁶H_5/2 to ⁴D_3/2, ⁶P_7/2, ⁶P_3/2, ⁶P_5/2, ⁴I_13/2, and ⁴I_11/2 respectively. The transition from ⁶H_5/2 to ⁶P_3/2 had the highest intensity and was associated with a peak at 400 nm. The bright yellow, reddish-orange, and red emission bands of the Sm³⁺ ions in the oxide glasses are related to the ⁴G_5/2 → ⁶H_5/2, ⁴G_5/2 → ⁶H_7/2, and ⁴G_5/2 → ⁶H_9/2 emission transitions, respectively.