Relation between the Ω6 intensity parameter of Er3+ ions and the 151Eu isomer shift in oxide glasses

Abstract

The Ω_t intensity parameters (t=2,4,6) of Er³⁺ ions in several oxide glasses and the isomer shift (IS) of ¹⁵¹Eu Mössbauer spectra in glasses of the same composition were determined. Among these Ω_t’s, the Ω₆ parameter was found to have a good relation with IS; Ω₆ decreases with an increase of IS which reflects the 6s electron density of rare‐earth ions. From the theoretical expression of Ω_t, Ω₆ is considered to be more affected by the overlap integrals of the 4f and 5d orbitals than Ω₂ and Ω₄, and to increase with an increase of these overlap integrals. These overlap integrals are supposed to decrease when the 6s electron density is larger, since the 6s electron density shields the 5d electron orbital.