The influence of the ratio between Li2O and B2O3 on optical, luminescence, and thermal properties of samarium-doped lithium borate glass

The advantageous characteristics of photoluminescence in lithium borate glass indicate that alterations in the microstructural unit greatly influence these properties. This work used FTIR spectroscopy in conjunction with peak fitting and density analysis to study the x Li₂O·(100-x) B₂O₃-1 Sm₂O₃, where x = 20, 33.33, 50, 66.66, and 75 mol% glass. Using quantitative analysis of the FTIR spectrum, it was possible to determine how the trend of each structural unit and the tetracoordinated boron content changed as the Li₂O concentration increased. The fundamental structural components (BØ₃, BØ₂O, and BØ₄) of the lithium borate glass were found to correlate with its attributes (density, and molar volume). The compositional changes revealed a shift in the BO₄ and BO₃ groups within the glass network. Furthermore, an improvement in the tightness of the glass network was noted, which enhanced the LiBSm: Sm glasses' thermal stability and glass-forming ability and demonstrated their applicability as lasing materials. In addition to the reduction of dangling bonds, the optical characteristics reveal the ionic nature surrounding Sm³⁺ ions. Optically, all the distinctive optical absorption bands of the Sm³⁺ ions appeared in the spectral region of 200-2500 nm at 2014 nm, 1582 nm, 1514 nm, 1462 nm, 1396 nm, 1216 nm, 1070 nm, 936 nm, 470 nm, 460 nm, 400 nm, 372 nm, and 358 nm. Additionally, a significant impact of the BO₄/BO₃ ratio on the optical properties was observed. The trend Ω₄ > Ω₆ > Ω₂ for observed Sm³⁺ absorption transitions is followed by the estimated oscillator strengths and Judd-Ofelt parameters (Ω₂, Ω₄, Ω₆) for reported Sm³⁺ absorption transitions. When the host glass was excited with violet wavelengths of 393 and 403 nm, three wavelengths were produced: one in the green area at 564 nm, one in the orange region at 600 nm, and one in the red region at 646 nm. As the excitation wavelength increased, a notable improvement in radiation intensity was noted. It was also discovered that the modification of the borate groups in the lattice structure affected the color emission and purity. This set of samples is a good fit for optoelectronic applications.