Calcium-assisted reduction of cobalt ferrite nanoparticles for nanostructured iron cobalt with enhanced magnetic performance
- 190 Downloads
This paper demonstrates the potential of a calcium-assisted reduction process for synthesizing fine-grain (~100 nm) metal alloys from metal oxide nanoparticles. To demonstrate the process, an iron cobalt alloy (Fe66Co34) is obtained by hydrogen annealing 7-nm cobalt ferrite (CoFe2O4) nanoparticles in the presence of calcium granules. The calcium serves as a strong reducing agent, promoting the phase transition from cobalt ferrite to a metallic iron cobalt alloy, while maintaining high crystallinity. Magnetic measurements demonstrate the annealing temperature is the dominant factor of tuning the grain size and magnetic properties. Annealing at 700 °C for 1 h maximizes the magnetic saturation, up to 2.4 T (235 emu/g), which matches that of bulk iron cobalt.
KeywordsMagnetic nanomaterials Iron cobalt Calcium-assisted reduction High saturation Grain evolution
This work was supported in part by the US Army Research Office (W911NF-09-1-0511) and National Science Foundation (CMMI-1451993). The authors thank Stefan Kelly for assistance in the DLS measurements, Lorena Maldonado-Camargo and Dr. Carlos Rinaldi for making the FC/ZFC measurements, and the UF MAIC facility for the invaluable support in material characterization.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- Coey JMD (2010) Magnetism and magnetic materials. Cambridge University Press, Cambridge, p 386Google Scholar
- Levy M, Quarta A, Espinosa A, Figuerola A, Wilhelm C, García-Hernández M, Genovese A, Falqui A, Alloyeau D, Buonsanti R, Cozzoli PD, García MA, Gazeau F, Pellegrino T (2011) Correlating magneto-structural properties to hyperthermia performance of highly monodisperse iron oxide nanoparticles prepared by a seeded-growth route. Chem Mater 23:4170–4180CrossRefGoogle Scholar
- Popova AN (2012) Synthesis and characterization of iron-cobalt nanoparticles. J Physics: Conf Series 345:012030Google Scholar
- van Schooneveld MM, Campos-Cuerva C, Pet J, Meeldijk JD, van Rijssel J, Meijerink A, Erné BH, de Groot FM (2012) Composition tunable cobalt–nickel and cobalt–iron alloy nanoparticles below 10 nm synthesized using acetonated cobalt carbonyl. J Nanopart Res 14:1–13Google Scholar