Influence of Al3+ doping on structural and magnetic properties of CoFe2-xAlxO4 Ferrite nanoparticles.

A series of Al 3+ substituted CoFe 2-x Al x O 4 ( x = 0.0 to 0.9) ferrite nanoparticles were synthesized via autocombustion method. XRD data show that all the samples exhibit single phase cubic spinel structure where the lattice parameter was observed to decrease linearly with increasing Al 3+ content. Structurally Al 3+ doping was observed to bring in grain refinement and increase dislocation density in CoFe 2-x Al x O 4 . The magnetic parameters namely saturation magnetization, M S , coercive field, H C , and remanent magnetization, M r vary significantly with Al 3+ doping. The Al 3+ doping resulted in reduction in Ms and Hc due to magnetic dilution effect and reduction in anisotropy constant K1 , respectively. Room temperature Mössbauer spectra were analyzed to extract cation distribution and hyperfine parameters. The hyperfine magnetic field decreases at both tetrahedral (A) and octahedral (B) interstitial sites with the increase in Al 3+ content. The Mössbauer spectral analysis reveals that Al 3+ has preference for the tetrahedral A site and Co 2+ prefers B sites. [ABSTRACT FROM AUTHOR]