Theoretical analysis of EPR parameters and local structure for Fe3+ ion in cadmium chloride crystal

This paper reports a novel application of ligand-field model to the detection of the local molecular structure of the (FeCl6)3− co-ordination complex. Based on the ligand-field model, the formulas relating the microscopic spin Hamiltonian parameters with the crystal structure parameters are derived. Using the theoretical formulas, the complete energy matrices of the electron–electron repulsion, the ligand field and the spin–orbit coupling for d 5 configuration ion in a trigonal ligand field are constructed. By diagonalizing the complete energy matrices, the local distortion structure R = 2.455 Å to 2.399 Å, θ = 58.95 2 ∘ to 59.559∘ of Fe3+ ion in the CdCl2:Fe3+ complex system are determined. It is found that the theoretical results are in good agreement with the experimental values. Moreover, in order to understand the detailed physical and chemical properties of the CdCl2, the theoretical values of the zero-field-splitting parameters and the corresponding distortion parameters in the range of 4.2 K ≤ T ≤ 293 K are reported firstly.