Investigations on the local structure and the EPR parameters for the tetragonal Ni+ center in CaF2

Ji-Zi Lin and Pei Xiao

Abstract

In this work, the local structure and the electron paramagnetic resonance (EPR) parameters g factors g// and g┴ and the hyperfine structure constants A// and A┴ of a tetragonal Ni+ center (i.e.,[NiF4]3-cluster) in CaF2 are theoretically investigated, using the high order perturbation formulas of these parameters for a 3d9 ion in tetragonal symmetry (elongated octahedron), in these formulas, the contributions to the spin Hamiltonian parameters from the s-and p-orbitals as well as the spin-orbit coupling coefficient of the ligands are taken into account. On the basis of the studies, the impurity Ni+ is found to locate at the distance of about 0.355 Šfrom the nearest fluorine plane. The calculated EPR parameters based on the above local structure in this work are in agreement with the experimental data.