Influence of Nd3+ substitution on thermoelectric power of Zn-Mg ferrite system

Polycrystalline ferrites, ZnxMg1-xFe2-yNdyO4 (x = 0.00, 0.20, 0.40, 0.60, 0.80 and 1.00; y = 0.00, 0.05 and 0.10) were prepared by standard ceramic method. X-ray diffraction study of these compositions revealed the formation of single phase spinels. Seebeck coefficient was obtained from thermo emf measurement by keeping constant temperature difference of 10 K across the pellet. The values of Seebeck coefficient were found to be negative showing majority charge carriers of n-type, suggesting the mechanism of conduction to be predominantly by electron hopping. The substitution of Nd3+ ion, which perhaps resides at the B-site, resulting in a decrease in the Seebeck coefficient. This decrease was assigned to the decrease of population of Fe3+ ion at the B-site. The activation energies calculated both from mobility plots and from de resistivity plots were found comparable. The Fermi energy, E-F(0), which was estimated by intrapolation of EFT curves to T = 0 K, was found less than the activation energy. This difference was attributed to electron hopping energy.