title: Investigations of the EPR zero-field splitting and the defect structure for Mn(2+) and Fe(3+) ions in anatase crystals.
abstract: The EPR zero-field splittings D of Mn(2+) and Fe(3+) ions in anatase crystals at room and low temperatures are calculated from the high-order perturbation formula of zero-field splitting D for 3d(5) ions in tetragonal symmetry based on the dominant spin-orbit coupling mechanism. The calculated results are consistent with the observed values. From the calculations, Mn(2+) and Fe(3+) ions are suggested to substitute for Ti(4+) ions in anatase (in the previous paper, Mn(2+) ion was suggested at an interstitial site rather than substitutional site) and the defect structures (characterized mainly by the local oxygen parameter u) for both tetragonal Mn(2+) and Fe(3+) impurity centers are estimated. The different zero-field splitting at room and low temperatures are due mainly to the change of local oxygen parameter u with the temperature. These results are discussed.
authors.affiliation: Department of Material Science, Sichuan University, Chengdu, PR China.
authors.forename: Gui-Qiang
authors.initials: GQ
authors.lastname: Qu
authors.forename: Xiao-Xuan
authors.initials: XX
authors.lastname: Wu
authors.forename: Wen-Chen
authors.initials: WC
authors.lastname: Zheng
mesh_terms: D003460:Crystallization; D004578:Electron Spin Resonance Spectroscopy; D007501:Iron / Q000737:chemistry*; D008345:Manganese / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*
chemical_list: C009495:titanium dioxide; D008345:Manganese; D014025:Titanium; D007501:Iron