A. MungchamnankitP. LimsuwanK. ThongchamS. MeejooKing Mongkuts University of Technology ThonburiMahidol University2018-07-122018-07-122008-02-01Journal of Magnetism and Magnetic Materials. Vol.320, No.3-4 (2008), 479-482030488532-s2.0-35448963090https://repository.li.mahidol.ac.th/handle/20.500.14594/19408X-band ESR spectra of natural zircon were measured at room temperature with the applied magnetic field parallel and perpendicular to the crystal axis [0 0 1]. Seven resonance absorption peaks of Zeeman interaction are obtained, due to a trace of the Gd3+present in the natural zircon. The ground state of Gd3+,8S7/2give rise to seven resonance absorption peaks under an applied magnetic field. In addition, the weak hyperfine structure lines are observed between adjacent Zeeman lines, due to isotope157Gd3+and155Gd3+. The ESR spectra were also measured at the different rotation angle θ and φ from 0 to 180° with respect to the applied magnetic field. The angular variation of ESR spectra of Gd3+with the applied magnetic field clearly reflected that the crystal field symmetry of the surrounding of Gd3+is D2d, and hence Gd3+substituted Zr4+in the lattice. According to the crystal field, it was shown that the ground state energy level of the Gd3+was split into four doublets. © 2007 Elsevier B.V. All rights reserved.Mahidol UniversityMaterials SciencePhysics and AstronomyArticleSCOPUS10.1016/j.jmmm.2007.07.014