Polycrystalline ferrites, Zn_xMg_1−xFe_2−yNd_yO₄ (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 ofn-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 dc resistivity plots were found comparable. The Fermi energy,E_F(0), which was estimated by intrapolation ofE_F-T curves toT = 0 K, was found less than the activation energy. This difference was attributed to electron hopping energy.

Compositions of polycrystalline Zn_𝑥Mg_1-𝑥Fe_2–𝑦Nd_𝑦O₄ (𝑥 = 0.00, 0.20, 0.40, 0.60, 0.80 and 1.00; 𝑦 = 0.00, 0.05 and 0.10) ferrites were prepared by standard ceramic method and characterized by X-ray diffraction, scanning electron microscopy and infrared absorption spectroscopy. Far infrared absorption spectra show two significant absorption bands, first at about 600 cm^–1 and second at about 425 cm^–1 , which were respectively attributed to tetrahedral (A) and octahedral (B) sites of the spinel. The positions of bands are found to be composition dependent. The force constants, $K_T$ and $K_O$, were calculated and plotted against zinc concentration. Compositional dependence of force constants is explained on the basis of cation–oxygen bond distances of respective sites and cation distribution.