EFFECT OF SUBSTITUTION OF IN(3+) IONS ON THE ELECTRICAL AND MAGNETIC-PROPERTIES AND MOSSBAUER STUDY OF MG0.9MN0.1INXFE2-XO4 FERRITES

The effect of substitution of diamagnetic In3+ ions on the electrical and magnetic properties of Mg-Mn ferrites was studied in the ferrite series Mg0.9Mn0.1InxFe2-xO4 where x varied from 0-0.8 in steps of 0.1. The incorporation of In3+ ions in place of Fe3+ ions resulted in an increase of lattice parameter owing to the larger size of the substituted ions, and an increase of d.c. resistivity owing to reduction of Verwey's hopping mechanism. It also resulted in improvement of saturation magnetization and produced a marked increase in the value of initial permeability, thus upgrading the bulk magnetic properties of these ferrites. These bulk magnetic properties improve due to substitution of diamagnetic In3+ ions, x, up to 0.5 only, whereas they deteriorate for a higher content of In3+ ions. The variations of saturation magnetization have been explained on the basis of modified cation distribution and their magnetic interactions. A large increase in the value of initial permeability has been attributed to its dependence on M(s) and magnetocrystalline anisotropy constant. A comparison of bulk magnetic properties with the inferences drawn from Mossbauer studies of these samples shows a similar trend. It is concluded that the substitution of In3+ ions, x, up to 0.5 in Mg-Mn ferrites results in the production of a hyperfine field at A as well as B sites, followed by ferromagnetic relaxation and paramagnetic transition for higher concentrations of In3+ ions. These variations have been explained on the basis of the effect produced by In3+ ions on the magnetic interactions, supertransferred hyperfine fields and domain-wall oscillations.