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

[摘要] Polycrystalline ferrites, Zn_ð‘�?Mg_{1â€�?�ð�?��?}Fe_{2â€�?�ð�?��?}Nd_ð‘�?O₄ (ð‘�? = 0.00, 0.20, 0.40, 0.60, 0.80 and 1.00; ð‘�? = 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 ð‘�??-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 of 𝐸_𝐹â€�?�ð�?��?? curves to ð‘�?? = 0 K, was found less than the activation energy. This difference was attributed to electron hopping energy.

[学科分类] 材料工程

[关键词] Polycrystalline ferrite;rare-earth;Seebeck coefficient;electron hopping;Fermi energy.