The Changed Crystal Filed of Gd3+ in Natural Zircon with Heat Treatment in Oxidizing and Reducing Atmosphere Monitor by ESR Spectroscopy

The main purpose of this research is dedicated to the ESR study of the impurity ions such as Gd3+ in the natural zircon crystal because the presence of the impurity ions in the crystal usually causes color in crystal. The Zeeman interaction, the weak hyperfine interaction and the crystal field interaction due to the environments of the impurity ions will be calculated. Furthermore, the relation between the resonance magnetic field positions in the ESR spectra and the applied magnetic field directions will reflect the impurity ion site symmetry. The change in the crystal field parameters of heat-treated zircon at different atmospheres were related to the change in the color of zircon.