Theoretical study of local structure for Ni 2+ ions at tetragonal sites in K 2ZnF 4:Ni 2+ system

Abstract

A theoretical method for studying the local lattice structure of Ni 2+ ions in (NiF 6) 4− coordination complex is presented. Using the ligand-field model, the formulas relating the microscopic spin Hamiltonian parameters with the crystal structure parameters are derived. Based on the theoretical formulas, the 45 × 45 complete energy matrices for d 8 ( d 2) configuration ions in a tetragonal ligand-field are constructed. By diagonalizing the complete energy matrices, the local distortion structure parameters ( R ⊥ and R ||) of Ni 2+ ions in K 2ZnF 4:Ni 2+ system have been investigated. The theoretical results are accorded well with the experimental values. Moreover, to understand the detailed physical and chemical properties of the fluoroperovskite crystals, the theoretical values of the g factor of K 2ZnF 4:Ni 2+ system at 78 and 290 K are reported first.