Preparation and characterization of nanosize nickel-substituted cobalt ferrites (Co1−xNixFe2O4)

✍ Scribed by Sonal Singhal; J. Singh; S.K Barthwal; K. Chandra

• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 490 KB
• Volume: 178
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1016/j.jssc.2005.07.020

✦ Synopsis

Nanosize nickel-substituted cobalt ferrites were prepared using aerosol route and characterized by TEM, XRD, magnetic and Mo¨ssbauer spectroscopy. The particle size of as obtained samples was found to be $10 nm which increases upto $80 nm on annealing at 1200 1C. The unit cell parameter 'a' decreases linearly with the nickel concentration due to smaller ionic radius of nickel. The saturation magnetization for all the samples after annealing at 1200 1C lies in the range 47.6-84.5 emu/g. Room temperature Mo¨ssbauer spectra of as obtained samples exhibit a broad doublet, suggesting super paramagnetic nature of the sample. The broad doublet is further resolved into two doublets corresponding to the iron atoms residing at the surface and internal regions of the particle. The samples annealed at 1200 1C showed broad sextet, which is resolved into two sextets, corresponding to tetrahedrally and octahedrally coordinated Fe cations. Cation distribution calculated using XRD and Mo¨ssbauer data indicates a decrease in Fe 3+ (oct.)/Fe 3+ (tet.) ratio with increasing nickel concentration.