Theoretical study of electron paramagnetic resonance spectrum for [formula omitted] ion in [formula omitted] system

Abstract

The electron paramagnetic resonance spectrum of the KMgF 3 : Fe 3 + system has been studied on the basis of the complete energy matrices for the electron–electron repulsion, the ligand-field and the spin–orbit coupling of d 5 configuration ion with a trigonal symmetry. A two-layer-ligand model, which includes six F - ions in the first layer and eight next nearest-neighbor K + ions in the second layer, has been proposed to describe the real ligand-field. By simulating the second-order and fourth-order EPR parameters D and ( a - F ) simultaneously, a displacement of a K + ion along C 3 -axis towards the Fe 3 + ion has been found theoretically, and this displacement will give rise to the distortion of the octahedron constructed by six F - ligand ions in the first layer. Δ Z is used to describe the displacement of a K + ion along C 3 -axis towards the Fe 3 + ion, and two angles θ 1 and θ 2 between the Fe 3 + – F - band and C 3 -axis are taken to describe the local distortion along the [1 1 1] direction. By adjusting the Δ Z , the range of the local distortion parameters Δ θ 1 = 5 . 54 ∘ – 6 . 07 ∘ , Δ θ 2 = - 4 . 60 ∘ to - 5 . 00 ∘ are determined, and the EPR spectrum of the KMgF 3 : Fe 3 + system has been satisfactorily explained by the two-layer-ligand model.