Structure and optical absorption of Sm3+ and Nd3+ ions in cadmium bismuth borate glasses with large radiative transition probabilities

Abstract

Glasses having compositions 20CdO⋅xBi2O3⋅(79.5−x)B2O3 (15⩽x⩽35) doped with 0.5mol% of Sm3+ and Nd3+ ions were prepared by melt quench technique. The amorphous nature of the glasses was confirmed by X-ray diffraction studies. The spectroscopic properties of the glasses were investigated using optical absorption and fluorescence spectra. The structural investigations of these glasses were carried out by recording the Fourier transform infrared spectra. The Judd–Ofelt intensity parameters Ωλ (λ=2, 4, 6) and other radiative properties like radiative transition probability, radiative life time, branching ratio and stimulated emission cross-section of the prepared glasses have been calculated. The variation of Ω2 with Bi2O3 content has been attributed to changes in the asymmetry of the ligand field at the rare earth ion site and to the changes in their rare earth oxygen (RE-O) covalency. The shift in the hypersensitive band shows that the covalency of the RE-O bond increases with increase of Bi2O3 content, and it is attributed to the increased interaction between the rare earth ions and the non-bridging oxygens (NBO’s). The radiative transition probabilities of the rare earth ions are large in cadmium bismuth borate glasses, suggesting their suitability as a potential candidate for laser application. Further, the FTIR results reveal that the glasses have BO3, BO4 and non-bridging oxygen as local structure.