Influence of High-Temperature Annealing on Structural and Magnetic Properties of Crystalline Cobalt Ferrite Nanoparticle
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ORIGINAL PAPER
Influence of High-Temperature Annealing on Structural and Magnetic Properties of Crystalline Cobalt Ferrite Nanoparticles in the Single-Domain Regime Gassem M. Alzoubi1
· B. A. Albiss2 · M. Shatnawi1 · I. Bsoul3 · A. M. Alsmadi1,4 · B. Salameh4 · G. A. Alna’washi1
Received: 7 April 2020 / Accepted: 23 May 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract We have carried out a systematic study on the effect of high-temperature annealing on the structural and magnetic properties of ultra-small crystalline cobalt ferrite nanoparticles prepared by the hydrothermal method. The structural and the magnetic characterizations of nanoparticles were investigated by XRD, TEM, FTIR, and VSM. The results of Rietveld refinement revealed that the nanoparticles have a cubic single-phase spinel structure. High-temperature annealing was found to increase the lattice parameter and average crystallite size of the cobalt ferrite nanoparticles. The TEM measurements showed that the nanoparticles were monodisperse and spherical in shape. The FTIR results confirmed the single-phase nature of the prepared nanoparticles. The magnetic measurements showed that the nanoparticles were ferromagnetic over a wide temperature range. We have observed that the high-temperature annealing increased both the saturation magnetization and magnetocrystalline anisotropy and decreased the coercivity. We demonstrated that magnetic field induced superparamagnetism can be induced by applying stronger magnetic fields that were able to shift the blocking temperature (TB ) down to below room temperature, resulting in a superparamagnetic behavior above TB . Keywords Superparamagnetism · Blocking temperature · Rietveld refinement · Magnetization · Spin-glass behavior
1 Introduction Magnetic ferrites have attracted much attention due to their potential applications in various technological fields such as permanent magnets, chemical sensors, highdensity recording systems, microwave devices, and also in biomedical applications [1–7]. Among these ferrites, cobalt ferrite CoFe2 O4 , is of particular interest as it exhibits some exceptional physical and chemical properties, such as high coercivity, large magnetic
Gassem M. Alzoubi
[email protected] 1
Department of Physics, The Hashemite University, 13115 Zarqa, Jordan
2
Department of Physics, Jordan University of Science and Technology, 22110 Irbid, Jordan
3
Department of Physics, Al al-Bayt University, Mafraq, 13040, Jordan
4
Department of Physics, Kuwait University, 13060 Safat, Kuwait
anisotropy, moderate saturation magnetization, high resistivity, and good mechanical and chemical stabilities [8–10]. Cobalt ferrite crystallizes into a cubic inverse-spinel structure with a space group Fd3m. The unit cell of cobalt ferrite is composed of eight formula units [CoFe2 O4 ]8 , in which, in the ideal structure, oxygen ions form a cubic close-packed FCC lattice, with Co2+ ions occupying the octahedral interstitial sites (B sites) and Fe3+ ions are equally distributed
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