Origin of the uniaxial magnetic anisotropy in cobalt ferrite induced by spark plasma sintering. Issue 4 (15th February 2023)

• Record Type: Journal Article
• Authors: Aubert, A.; Garitaonandia, J.S.; Maccari, F.; Brötz, J.; Skokov, K.; Gutfleisch, O.
• Is Part Of: Ceramics international. Volume 49:Issue 4(2023)
• Page Start: 5630
• Page End: 5636
• Publication Date: 2023-02-15
• Subjects: CoFe2O4 -- Spinel -- Magnetic anisotropy -- Spark plasma sintering -- Mössbauer spectroscopy; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2022.11.065
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Cobalt ferrite (CFO) is a promising candidate for magnetostrictive applications like actuators or sensors. We have recently shown that uniaxial magnetic anisotropy can be induced in CFO by reactive sintering using spark plasma sintering (SPS), which leads to an improvement of its magnetostrictive properties. However, the origin of the anisotropy and the formation mechanism remain unexplained so far. In this study, different SPS processes have been conducted to determine which parameter is responsible for the induced uniaxial anisotropy. We demonstrate that the magnetic anisotropy arises during the cooling step when done under SPS's uniaxial compression. In addition, we also investigate the fundamental origin of the magnetic anisotropy induced during the SPS process. We show that the polycrystalline anisotropic cobalt ferrite obtained after SPS exhibits no texture. However, the SPS samples turn isotropic after being annealed in air at 400 °C/2 h, as shown by magnetic and magnetostrictive measurements. A change in ionic distribution after the annealing is also observed by Mössbauer spectroscopy. Our findings suggest that the induced magnetic anisotropy results from the ionic distribution of the Co 2+ in the CFO's spinel lattice, a mechanism previously observed in magnetic annealed CFO. This study advances the in-depth understanding of the relationship between SPS processing and magnetic properties of cobalt ferrite.