Preferential Site of Gd in Gd-Doped Fe3O4 Nanopowder

Both structural refinement using X-ray powder diffraction data and energy calculation using quantum mechanics were used to determine the site preference and the amount of Gd in the host lattice of Gd doped Fe3O4 [Gd-x Fe3-xO4 (x = 0.1)] nanopowder prepared by the sonochemical method. Among possible cation-disorder models, the model proposed by structural refinement, in which Gd ions might preferentially occupy the octahedral sites in Gd doped Fe3O4 having the inverse spinel structure, was confirmed by geometry energy calculation using a first-principle based on the density-functional theory. The final converged weighted R-factor, R-wp, and the goodness-of-fit indicator, S (= R-wp/R-e) were 6.73% and 1.22, respectively. The occupancy of Gd ions occupying octahedral sites was 0.04(2).