Enhancement of maximum energy product in exchange-coupled BaFe12O19/Fe3O4 core-shell-like nanocomposites

Combined characterization approaches to investigate magnetostructural effects in exchange-spring ferrite nanocomposite magnets

“…Theoretical predictions suggest that an exchange-spring nanocomposite made by the mixing of two different nanomagnetic phases (hard-soft composite) can enhance the M S while maintaining a high H C and thereby improve the (BH) max . [18][19][20][21][22] Mixing the hard and soft phases at the nanoscale is expected to result in an exchange-spring nanocomposite magnet wherein the soft phase enhances magnetization of the composite and the hard phase stabilizes the composite against demagnetization. 17,23,24 The concept of an exchange-spring magnet was proposed in 1991 by Kneller and Hawing in their seminal paper.…”

“…24,[26][27][28] Oxide-based exchange-spring magnets are attractive alternatives due to the low cost and high corrosion resistance along with relative tolerance of magnetic performance to defects. 19,20,[29][30][31][32][33] Magnetic ferrites are widely used magnets, where hexaferrites presents a high H C material (B500 kA m À1 ), while spinel ferrites are attributed with high M S (B90 Am 2 kg À1 ). 16,19,20,34,35 The magnetoplumbite strontium hexaferrite (SrFe 12 O 19 ; space group: P6 3 /mmc) is formed of a hexagonally packed lattice of oxygen ions with every 5th layer having one oxygen ion replaced by a strontium ion.…”

“…19,20,[29][30][31][32][33] Magnetic ferrites are widely used magnets, where hexaferrites presents a high H C material (B500 kA m À1 ), while spinel ferrites are attributed with high M S (B90 Am 2 kg À1 ). 16,19,20,34,35 The magnetoplumbite strontium hexaferrite (SrFe 12 O 19 ; space group: P6 3 /mmc) is formed of a hexagonally packed lattice of oxygen ions with every 5th layer having one oxygen ion replaced by a strontium ion. The iron ions occupy interstitial sites within the oxygen sublattice.…”

Topical Review: Progress and Prospects of Hard Hexaferrites for Permanent Magnet Applications

“…Although small crystallites were obtained, no clear improvements in remanence are reported and the composites appear to be decoupled based on the demagnetization curves. Core-shell BFO/Fe 3 O 4 core-shell-like particles were the focus of Mohseni et al work [201]. Larger BFO particles are seen to have their surface covered by small magnetite nanoparticles.…”

Effect of Rare-Earth Co-Doping on the Microstructural and Magnetic Properties of BaFe12O19

“…In addition, co-doped Tm-Tb, Eu-Nd, Sm-Co Ba-hexaferrites have also been investigated and have been shown that co-doping of the rare-earth ions provides hexaferrites with a rise in the magnetization and/or coercivity [24][25][26][27]. Among other magnetic properties, some attempts have also been made to improve the maximum energy product, (BH)max for Srhexaferrites and Ba-hexaferrites using La-Sm [28,29].Researchers have different manufacturing methods to produce hexaferrites such as traditional ceramic methods [30][31][32][33][34] or several chemical methods [35][36][37][38][39][40][41].…”