Theoretical studies of the defect structures and the spin Hamiltonian parameters for the Pd+ and Pd3+ centers in NH4Cl

The defect structures and the spin Hamiltonian parameters (i.e., g factors and superhyperfine parameters) are theoretically studied for the tetragonal Pd+ and Pd3+ centers in NH4Cl from the perturbation formulas of these parameters for 4d9 and 4d7 ions in tetragonally elongated and compressed octahedra. The elongated Pd+ center can be ascribed to the square planar [ PdCl 4 ] 3 - complex. The compressed Pd3+ center is attributed to the interstitial Pd3+ associated with two adjacent axial cations replaced by two water molecules as the charge compensators (i.e., [ PdCl 4 ( H 2 O ) 2 ] - complex). The theoretical spin Hamiltonian parameters show good agreement with the experimental data. The results are discussed.