STUDIES OF POLYCRYSTALLINE COBALT-SUBSTITUTED LITHIUM FERRITES

The lattice constant, density, electrical conductivity, activation ene rgy, carrier concentration, mobility, Seebeck coefficient, and ferroma gnetic resonance linewidth were studied on a series of cobalt-substitu ted lithium ferrites, We have found that all the samples studied have single phase spinel structure. The lattice constant and the density ar e increased with substituting Co2+ contents. All the specimens studied have two regions of different activation energies, In the region belo w T-a (below 220 degrees C), the conduction is attributed to electron hopping from Fe2+ to Fe3+; and in the region above T-a (above 220 degr ees C), it is attributed to ionic diffusion of Li ion. The change of m obility is caused by the dispersion of ions, The ferromagnetic resonan ce (F.M.R.) experimental results indicated that cobalt substitution af fects linewidths and relaxation frequency, but it does not affect the g-factor.