Investigations of the spin-Hamiltonian parameters and tetragonal distortions due to Jahn–Teller effect for the monovalent d 9 (Ni +, Pd +, Pt +) impurity centers in AgCl crystals

Abstract

When the monovalent md 9 ions Ni + (3d 9), Pd + (4d 9) and Pt +(5d 9) substitute for the Ag + ions in AgCl crystal, the cubic chlorine octahedron surrounding Ag + in the host AgCl crystal distorts into the tetragonally elongated octahedron in the md 9 impurity center owing to the Jahn–Teller effect. The spin-Hamiltonian parameters ( g factors g ||, g ⊥ and hyperfine structure constants A ||, A ⊥) of the tetragonal md 9 centers in AgCl are calculated from the high-order perturbation formulas based on the cluster approach, in which the admixture between d orbitals of d n ion and p orbitals of ligand ion via covalence effect are taken into account. From the calculations, the spin-Hamiltonian parameters of these tetragonal md 9 centers in AgCl are explained reasonably and the tetragonal distortions (characterized by the tetragonal elongation Δ R = R || − R ⊥, where R || and R ⊥ denote the metal–ligand distances parallel with and perpendicular to the tetragonal axis) of these centers due to Jahn–Teller effect are obtained. The results are discussed.