Annealing-Environment Effects on the Properties of CoPt Nanoparticles Formed in Single-Crystal Al₂O₃ by Ion Implantation

Journal Article · Sat Jan 01 04:00:00 EST 2005 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2138801· OSTI ID:978031

White, Clark W ^[1]; Withrow, Stephen P ^[1]; Budai, John D ^[1]; Thomas, Darrell Keith ^[1]; Williams, J. M. ^[2]; Meldrum, A. ^[3]; Sorge, K. D. ^[4]; Thompson, James R ^[1]; Ownby, Gary Webb ^[1]; Wendelken, J F ^[1]; Boatner, Lynn A ^[1]

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1. ORNL
2. BronteK Delta Corporation
3. University of Alberta, Edmondton, Canada
4. University of Nebraska, Lincoln

The ion implantation of nearly equal doses of Co and Pt into a single-crystal Al{sub 2}O{sub 3} host followed by thermal annealing leads to the formation of nanoparticles whose phase, structure, and physical properties are strongly dependent on the annealing environment. Annealing in 96%Ar+4%H{sub 2} gives rise to ferromagnetic, chemically ordered CoPt nanoparticles with the L1{sub 0} structure and a magnetic coercivity that can exceed 10 kOe at 5 K. Annealing in O{sub 2} (or in Ar) does not result in the formation of a CoPt alloy. Instead, the implanted Pt precipitates to form oriented elemental Pt nanoparticles, and the implanted Co combines with oxygen to form Co{sub 3}O{sub 4} oxide nanoparticles. Annealing in ultrahigh-vacuum conditions results in a mixture of phases including CoPt{sub 3} and Co{sub 3}O{sub 4} and possibly Co. The results obtained for Co+Pt-implanted Al{sub 2}O{sub 3} are compared with the previous results for Fe+Pt-implanted Al{sub 2}O{sub 3} annealed in similar environments.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 978031
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 11 Vol. 98; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANNEALING
ION IMPLANTATION
MIXTURES
OXIDES
OXYGEN
PHYSICAL PROPERTIES