Magnetic properties of ultrafine-grained cobalt samples obtained from consolidated nanopowders

✍ Scribed by Fellah, F. ;Chérif, S. M. ;Bouziane, K. ;Schoenstein, F. ;Jouini, N. ;Dirras, G.

• Book ID: 105366265
• Publisher: John Wiley and Sons
• Year: 2011
• Tongue: English
• Weight: 725 KB
• Volume: 208
• Category: Article
• ISSN: 0031-8965
• DOI: 10.1002/pssa.201026496

✦ Synopsis

Abstract

Co powders having nominal average particle size of 50 and 240 nm were synthesized using a polyol method and then consolidated by hot isostatic pressing (HIP) or the emerging spark plasma sintering (SPS) compaction processes. Bulk polycrystalline aggregates were obtained, having average grain sizes of about 200 and 300 nm, respectively. It is found that both nanoparticles and consolidated samples exhibit a soft ferromagnetic behavior. The magnetization reversal likely occurs by nucleation/propagation process. However, a curling process can be involved in the magnetization reversal for the smaller particles. The dynamic measurements provide for the consolidated samples magnetic parameters corresponding to bulk cobalt with vanishing anisotropy. The contribution of the intergranular region is found to be negligible. We can infer that the used consolidation routes insure a good magnetic interfacial contact between the particles.