https://doi.org/10.1051/epjap/2009138
Investigations on the defect structure and the EPR parameters for AgBr:Ir2+
1
Department of Applied Physics, University of Electronic Science and
Technology of China, Chengdu 610054, P.R. China
2
International Centre for Materials Physics, Chinese Academy of
Sciences, 110016 Shenyang, P.R. China
Corresponding author: shaoyi_wu@163.com
Received:
10
March
2009
Revised:
26
May
2009
Accepted:
28
May
2009
Published online:
17
September
2009
The defect structure and the EPR parameters (the g factors, the hyperfine structure constants and the superhyperfine parameters) for the tetragonal Ir2+ center in AgBr are theoretically investigated using the perturbation formulas of these parameters for a 5d7 ion in tetragonally elongated octahedra. In the calculations, the contributions from the ligand orbital and spin-orbit coupling interactions and the local lattice (elongation) distortion due to the Jahn-Teller effect are taken into account. Related molecular orbital coefficients and the ligand unpaired spin densities are determined quantitatively using a cluster approach. The impurity center is attributed to the substitutional [ IrBr6] 4− cluster on host Ag+ site, which suffers the relative elongation of about 0.08 Å along C4 axis due to the Jahn-Teller effect. The calculated EPR parameters based on the above Jahn-Teller elongation show good agreement with the observed values.
PACS: 71.70.Ch – Crystal and ligand fields / 75.10.Dg – Crystal-field theory and spin Hamiltonians / 76.30.He – Platinum and palladium group
© EDP Sciences, 2009
