Structural and magnetic studies of coprecipitated Me-spinel (Me = Co, Ni, Cu and Mg) ferrite nanoparticles

The report attempts to study some spinel such as cobalt (Co–F), nickel (Ni–F), copper (Cu–F) and magnesium (Mg–F) nanoferrites, which are synthesized by coprecipitation route and annealed at 850 °C for 2 h. Powder X-ray diffraction patterns depict the formation of single cubic spinel structure ( Fd-3m ). Thereby, lattice parameter is ranging between 8.3420 and 8.4009 Å, while average crystallite size is found in 20–38 nm. Transmission electron and scanning electron microscopies exhibit that the nanoparticles are agglomerated and revealing mixture of spherical and irregular shapes. The fit of Co–F, Ni–F and Cu–F room 57 Fe Mössbauer spectra was established with two sextets, which reflects that the Fe 3+ is occupied two sub-lattices of spinel system. A weak percentage of quadruple doublet, 2%, was observed in both Ni–F and Cu–F spectra. Exceptionally, the Mg–F room 57 Fe Mössbauer spectrum indicates broadening lines due to disordering of iron magnetic moments because of small nanoparticle size (20 nm), it was fitted with hyperfine field distribution, Mg–F spectrum was also collected at 6 K reflecting a ferrimagnetic ordering according to Néel’s theory. M(T) curves indicate that the blocking temperature is higher than 300 K, except the Mg–F sample shows a T B of ~226 K. Besides, the M(H) loops at 5 K exhibit a soft behavior and the magnetic parameters like M s , M r , µ e , M r /M s ration, H c and K a have determined for the studied spinel ferrites.