Electron paramagnetic resonance of non-Kramers ion in a fluorozirconate glass

Electron paramagnetic resonance of trivalent thulium and terbium ions in a multicomponent fluorozirconate glass is reported. A theoretical reconstruction is described that accounts well for the observed spectra. The signals arise from ions having doublet ground states with a continuous distribution of zero-field splittings from zero upwards. Spin Hamiltonian parameters were measured as: g/sub ///=13.7+or-0.3, A/sub ////g/sub /// mu B=24.5+or-1.0 mT for Tm3+ and g/sub ///=17.5+or-0.2, A/sub ////g/sub /// mu B=24.9+or-0.4 mT for Tb3+. These correspond to ions in essentially mod +or-6) states. Probable sites are discussed and the spectra are shown to be consistent with 8-coordinated Tm3+ in square antiprism sites and 9-coordinated Tb3+ in tricapped trigonal prism sites, although other types of site probably also occur.