Cold plasma reduction of surface carbon on SmCo5 nano-flakes prepared by surfactant-assisted ball-milling

• Published in: Journal of magnetism and magnetic materials Vol. 471; pp. 250 - 254
• Main Authors: Han, Guangbing, Wang, Ke, Elkins, Kevin E., Qiu, Zhaoguo, Timmons, Richard B., Savage, Charles R., Kang, Shishou, Liu, J. Ping
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-02-2019; Elsevier BV
• Subjects: Argon; Argon plasma; Ball milling; Carbon; Cold plasmas; Cold pressing; Demagnetization; Electrons; Flakes; Magnetic properties; Magnetism; Oleic acid; Plasma; Samarium base alloys; SmCo5; Surfactant removal; Surfactants; X-ray photoelectron spectroscopy (XPS); Surfactant removal; SmCo5; X-ray photoelectron spectroscopy (XPS); Argon plasma; Magnetic properties
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2018.09.057

•Cold plasma (>50 Watt) was used to remove carbon on surface of magnetic nanoflakes.•62.5 at.% of carbon removal was achieved on the SmCo5 nanoflakes treated 4 h.•No discernible changes in morphology were induced by cold plasma treatment.
Nano-flake SmCo5 powders with typical flake thickness of 200 nm were prepared by high energy ball milling using Oleic Acid (OA) as a surfactant. In order to remove the surfactant, the as-milled powders were exposed to pulse cold plasma of argon. The effects of the plasma parameters on residual surfactant content and magnetic properties of the resulting powder were investigated. Partial (62.5 at. %) surfactant removal was observed by XPS after treatments of 4 h at 150 Watt average power under an argon pressure of 300 mTorr. In addition, the cold plasma cleaning process led to a little bit of increase of oxygen on the surface. Demagnetization measurements revealed a slight decrease of the magnetic performance after plasma treatment. These results indicate that pulse cold plasma is an effective way for surfactant removal without morphological change and magnetic property degradation of the SmCo5 nano-flakes.