Influence of gadolinium concentration on the EMR spectrum of Gd3+ in zircon

Electron magnetic resonance (EMR) spectra of gadolinium-doped zircon (ZrSiO4) powders have been studied at room temperature for gadolinium concentrations between 0.20 and 1.0 mol%. The results suggest that Gd3+ ions occupy substitutional sites in the zircon lattice, that the electron magnetic resonance linewidth increases with increasing gadolinium concentration and that the range of the exchange interaction between Gd3+ ions is about 1.17 nm, larger than that of the same ion in other host lattices, such as ceria (CeO2), strontium oxide (SrO) and calcium oxide (CaO). The fact that the electron magnetic resonance linewidth of the Gd3+ ion in polycrystalline zircon increases, regularly and predictably, with Gd concentration, shows that the Gd3+ ion can be used as a probe to study, rapidly and non-destructively, the crystallinity and degradation of ZrSiO4.