EPR, Optical Absorption, and Superposition Model Studies of Fe^3+ Doped Dipotassium Tetrachloropalladate: a Case of Hyperfine Structure

Abstract

An electron paramagnetic resonance (EPR) study of Fe^(3+) doped dipotassium tetrachloropalladate single crystal is carried out at liquid nitrogen temperature. The spin Hamiltonian parameters are evaluated from the angular variation of the observed hyperfine lines. The EPR spectrum shows two sites. At site I, the Fe^(3+) ion enters the host lattice substitutionally replacing K+ ion, whereas at site II, the Fe^(3+) ion enters the lattice interstitially. Using EPR data local site symmetry within the host lattice is also discussed. The local site symmetry of the Fe^(3+) ion within the host lattice is orthorhombic. An optical absorption study is performed at room temperature. Using the optical absorption spectrum the bands were assigned and the Racah parameters and the cubic crystal field splitting parameter are determined. The evaluated values of the Racah parameters are B=845 cm^(-1), C=2082 cm^(−1), respectively, and the cubic crystal field splitting parameter is Dq=785 cm^(−1). The nature of the metal-ligand bonding within the crystal is determined using EPR and optical data. The crystal field parameter and zero-field splitting (ZFS) parameters are evaluated theoretically for both the sites using the superposition model and the microscopic spin Hamiltonian together with the perturbation equations, respectively. The theoretically evaluated ZFS parameters are in good agreement with the experimentally observed values.