SURFACE AND BULK CATION DISTRIBUTION OF THE SPINEL SYSTEM ZNXMG1-XFE2O4

ZnXMg1-XFe2O4 mixed oxide spinels (X = 0.0, 0.2, 0.4, 0.6, 0.8, and 1. 0) were prepared by conventional solid state reaction method. Bulk and surface characterization of these ferrites were carried out by differ ent techniques. The ratios Zn/Fe and Mg/Fe determined by PIXE and AAS were nearly as expected from the synthesis mixture, i.e. following the substitution model. XRD shows only a spinel structure (fcc) with incr easing lattice parameter as X increases from 0 to 1. The bulk ratios o f tetrahedral to octahedral sites occupied by Fe cations measured by N GR are in good agreement with the theoretical bulk stoichiometry. LETS results indicate a Mg substitution by Fe cations at the surface. Only octahedral sites are proposed at the surface. The transition from inv erse to normal spinel was follow through NGR-spectra occurring at X = 0.4.