title: Investigations on the defect structures and the g factors for the two orthorhombic Ti3+ centers in CaYAlO4.
abstract: The defect structures and the g factors for the two orthorhombic Ti(3+) centers (A and B) in CaYAlO(4) are theoretically investigated from the perturbation formulas of the g factors g(xi), g(eta) and g(xi) for a 3d(1) ion in orthorhombically distorted octahedra. The centers may be attributed to Ti(3+) locating on the Al(3+) site associated with one nearest-neighbouring oxygen vacancy (V(O)) along the z (or c) axis and additional next-nearest-neighbouring Ti(4+) replacing the host Al(3+) (Ti(Al), i.e., center A) or Al(3+) vacancy (V(Al), i.e., center B) perpendicular to the c axis, respectively. Due to the electrostatic interactions arising from the local charge mismatch, the central Ti(3+) undergoes a large displacement DeltaZ away from the V(O) in the c axis, while the ligand O(2-) intervening in the Ti(3+) and Ti(Al) (or V(Al)) suffers a small outward (or inward) shift DeltaX in the corresponding c plane related to the center of oxygen octahedron. The theoretical g factors for both centers based on the above displacements are in reasonable agreement with the observed values.
authors.affiliation: Department of Applied Physics, University of Electronic Science & Technology of China, Chengdu 610054, PR China. wushaoyi@netease.com
authors.forename: Shao-Yi
authors.initials: SY
authors.lastname: Wu
authors.forename: Ji-Zi
authors.initials: JZ
authors.lastname: Lin
authors.forename: Qiang
authors.initials: Q
authors.lastname: Fu
authors.forename: Hui-Ning
authors.initials: HN
authors.lastname: Dong
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D008956:Models, Chemical; D010087:Oxides / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*
chemical_list: D017610:Calcium Compounds; D010087:Oxides; D000535:Aluminum; D014025:Titanium