Enhancement of the physical properties of rare-earth-substituted Mn-Zn ferrites prepared by flash method

摘要

The effect of rare-earth ions on the structural, magnetic and electrical properties of rare-earth-doped manganese-zinc ferrite is reported. The compounds with the formula Mn_(0.5)Zn_(0.5)R_(0.05)Fe_(1.95)O_4 where R = Tb, La, Ce and Th, were prepared by the flash combustion technique. The prepared samples reveal that by introducing a relatively small amount of R(NO_3)_3 or R(Cl_3) instead of Fe_2O_3, an important modification of both structure and physical properties was obtained. Curie temperature, effective magnetic moment, electrical resistivity, density, thermoelectric and lattice constant were directly affected by these substitutions either by their partial diffusion in the spinel lattice or the formation of the crystalline secondary phases (orthoferrite and/or garnet) on the grain boundaries which suppress the abnormal grain growth. Correlation between the ionic radii and the measured physical properties were studied.