NEUTRON-SCATTERING STUDIES OF YB-BEARING SILICATE-GLASSES

The static and dynamic magnetic response of the Yb3+ ions in 3Na2O.Yb2O3.6SiO2 glass and the isochemical crystalline silicate Na3YbSi3O9 has been studied by neutron diffraction, inelastic magnetic scattering, and magnetic susceptibility measurements. The rare earth sites in the glass have an average coordination number of 5.6 +/- 0.5 and give a mean rare earth-oxygen bond length of 2.23 angstrom; average Si-O and O-O coordination numbers and bond distances are comparable to those in vitreous SiO2. The magnetic excitation spectrum of the Na3YbSi3O9 material was analyzed by a crystal field model using a method of descending symmetry. The magnetic susceptibility and the excitation spectrum of the Yb glasses can be described by a distribution of ligand field effects on the Yb3+ ions that are similar to the nominal crystal field in crystalline Na3YbSi3O9.