Semi-hard magnetic properties of nanoparticles of cobalt ferrite synthesized by the co-precipitation process

• Published in: Journal of alloys and compounds 2017-02, Vol.694, p.1295-1301
• Main Authors: Hosni, N., Zehani, K., Bartoli, T., Bessais, L., Maghraoui-Meherzi, H.
• Format: Article
• Language: English
• Subjects: Annealing; Carbon dioxide; Cobalt ferrites; Coercivity; CoFe2O4; Coprecipitation; Diffraction; Ferromagnetic materials; Heat treatment; Hysteresis loops; Magnetic properties; Nanoparticles; Physics; Rietveld refinement; Scanning electron microscopy; Spinel; Synthesis; Temperature; X-ray diffraction; β-Fe2O3
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2016.09.252

The nanoparticles ferromagnetic materials CoFe2O4 have been synthesized by the co-precipitation method and annealed at various temperatures from 773 to 1223 K. The influence of the heat treatment on the structural, morphological and magnetic properties of CoFe2O4 nanoparticles was investigated. The structure, morphology and magnetic properties of the annealing samples were reached by mean of X-ray diffraction (XRD), scanning electron microscopy (SEM) techniques and measurement of hysteresis loop. The average crystallite size, lattice parameter and X-ray density were calculated from X-ray diffraction data. All samples have the cubic spinel structure with average crystallite sizes increasing from 30 to 178 nm with the temperature. The results show that CoFe2O4 nanoparticles prepared by this method have small and more uniform size. The measurements of the hysteresis loop, performed at both 10 K and 300 K, indicate a ferromagnetic behavior of nanoparticles. Also the measurement at 300 K shows that the sample annealed at 1023 K is magnetically harder than the other samples. The coercive fields are 1.58 kOe against the values inferior at 0.61 kOe for the other samples. Indeed, the remanent magnetization is 31.85 emu g−1 for the hard magnetic sample against 13.02 and 17.29 emu g−1 for the soft magnetic samples annealed at 773 and 1223 K, respectively. The origin of the hard-soft magnetic properties of nanoparticles CoFe2O4 is discussed in terms of the co-existence of secondary phases β-Fe2O3, CoO2 and the distribution of Fe2+ and Co2+ ions within the lattice. [Display omitted] •The nanoparticles cobalt ferrite was synthesized in co-precipitation process.•Subsequently, the cobalt ferrite is annealed under air at different temperature between 773 and 1223 K.•Their Structural, morphological, and magnetic properties have been presented.•The samples annealed at 1023 K for 6 h possess a coercive field of 1.5 and 11.4 kOe at 300 K and 10 K respectively.•The sample annealed at 1023 K for 6 h exhibits the best (BH)max (BHmax = 0.5 MGOe at 300 K and 3.9 MGOe at 10 K).