Effect of Bi2O3 on the structural and spectroscopic properties of Sm3+ ions doped sodiumfluoroborate glasses

Abstract

Trivalent samarium ions doped bismuth sodiumfluoroborate glasses have been prepared with the chemical composition 40B2O3+(40−x)Na2CO3+xBi2O3+19CaF2+1Sm2O3 (where x = 0, 10, 20, 30 and 40 in wt%) following the conventional melt quenching technique. The structural and spectroscopic characterizations have been carried out using XRD, FTIR and UV–Vis–NIR, luminescence and decay measurements. Judd-Ofelt (JO) theory has been used to study the effect of local field environment around the Sm3+ ion site to calculate the radiative properties. Bonding parameters and JO intensity parameters (Ω2, Ω4, Ω6) were determined from the absorption spectra to explore the nature of bonding and symmetry around the Sm3+ ion site. The spectroscopic quality factor (χ = Ω4/Ω6) and asymmetry ratio (R/O) have been determined to elucidate the potential strength of the stimulated emission and asymmetry around the Sm3+ ion site in the prepared glasses. Using JO theory, various radiative properties like transition probability (A), effective bandwidth (Δλeff), stimulated emission cross-section (σpE) and branching ratio (βR) for the 4G5/2 → 6H5/2, 6H7/2, 6H9/2 emission levels of the prepared glasses were determined and compared with the reported literature. The decay curves corresponding to the 4G5/2 level of the Sm3+ ions were measured and are found to be single exponential for lower Bi2O3 content and turn to become non-exponential for higher Bi2O3 content and is due to the donor to acceptor energy transfer through cross-relaxation process. Among the prepared glasses, 40BiNFBS glass exhibit higher A, βR, σpE and η values and is suggested for useful gain medium and reddish orange laser applications.