Influence of silver doping on the physical properties of Mg ferrites

The physical properties of silver substituted magnesium ferrite MgAgxFe2-x O-4 (0.0 <= x <= 1) have been studied as a function of silver ion concentration. The samples were prepared using the flash combustion technique. The effect of Ag content on microstructure and magnetic properties has been studied. X-ray diffraction (XRD) analysis reveals the spinel structure besides metallic silver particle at all concentrations. The decrease in the lattice constant with increasing Ag up to the critical concentration (x = 0.2) was discussed. The close agreement of the theoretical and experimental lattice constant ratio from XRD pattern supports the occupancy of silver on the tetrahedral sites. The morphological features were studied using scanning electron microscope. The magnetic susceptibility, Curie temperature (T (C)), and effective magnetic moment (mu (eff)) were decreased with compositional parameter. The DC electrical conductivity of the investigated samples was measured and the results indicated the increase in conductivity with increasing Ag content from 5.6 x 10(4) at x = 0 to 12.6 x 10(4)Omega(-1) at x = 1. The transition from the ferrimagnetic to paramagnetic state is accompanied by an increase in the thermo EMF. Ag-Mg ferrite shows p-type conductivity at all concentrations of Ag particles where the creation of lattice vacancies is due to presence of Ag+ ions gives rise to the p-type conductivity.