Local structural properties of (NiF 6) 4− clusters in perovskite fluorides RbMF 3 (M = Cd 2+, Ca 2+, Mg 2+) series: EPR and optical spectra study in tetragonal and trigonal ligand field

Abstract

By analyzing EPR and optical spectra, the local lattice structures of (NiF 6) 4− clusters in perovskite fluorides RbMF 3 (M = Cd 2+, Ca 2+, Mg 2+) series in tetragonal and trigonal ligand field are studied. A compression distortion relative to the regular octahedron for the RbCdF 3:Ni 2+ and RbCaF 3:Ni 2+ systems is determined. Furthermore, on the basis of the complete energy matrices we found that ZFS parameter D dependence on spin–orbit coupling coefficient ζ is not a strictly quadratic relation as shown by the fourth-order perturbation formula. Finally, the curves of g ∥ versus k and g ⊥ versus k for these three systems are plotted which satisfy an approximately linear relation.