The effect of host glass composition on the optical absorption spectra of ${\mathrm{Nd}}^{3+}$, ${\mathrm{Sm}}^{3+}$, and ${\mathrm{Dy}}^{3+}$ in lead borate glasses, with PbO contents varying from 30 to 70 mol %, has been analyzed using Judd-Ofelt theory and the compositional dependence has been determined for the hypersensitive bands. Judd-Ofelt intensity parameters ${\mathrm{\Omega }}_{\mathit{t}}$ (t=2,4,6), and the radiative transition probabilities. The variation of ${\mathrm{\Omega }}_2$ with PbO content has been attributed to changes in the asymmetry of the ligand field at the rare-earth (R) site (due to the structural changes) and to changes in R-O covalency, whereas the variation of ${\mathrm{\Omega }}_6$ has been related to the variation in R-O covalency. The radiative transition probabilities of the rare-earth ions are large in lead borate glasses suggesting their suitability for laser applications. © 1996 The American Physical Society.

• Received 10 November 1995

DOI:https://doi.org/10.1103/PhysRevB.53.6186