Theoretical studies of the g factors and local structures of the Ni3+ centers in Na2Zn(SO4)(2)center dot 4H(2)O and K2Zn(SO4)(2)center dot 6H(2)O crystals

摘要

The local structures and the g factors g(i) (i = x, y, z) for Ni3+ centers in Na2Zn-(SO4)(2)center dot 4H(2)O (DPPH) and K2Zn(SO4)(2)center dot 6H(2)O (PHZS) crystals are theoretically studied by using the perturbation formulas of the g factors for a 3d(7) ion with low spin (S = 1/2) in orthorhombically compressed octahedra. In these formulas, the contributions to g factors from both the spin-orbit coupling interactions of the central ion and ligands are taken into account, and the required crystal-field parameters are estimated from the superposition model and the local geometry of the systems. Based on the calculations, the Ni-O bonds are found to suffer the axial compression delta z (or Delta z) of about 0.111 angstrom (or 0.036 angstrom) along the z-axis for Ni3+ centers in DPPH (or PHZS) crystals. Meanwhile, the Ni-O bonds may experience additional planar bond length variation delta x (approximate to 00.015 angstrom) along x- and y-axes for the orthorhombic Ni3+ center in DPPH. The theoretical g factors agree well with the experimental data. The obtained local structural parameters for both Ni3+ centers are discussed.