Unusual behavior in magnesium-copper cluster matter produced by helium droplet mediated deposition

Journal Article · Sat Feb 28 00:00:00 EST 2015 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4913210· OSTI ID:22416180

Little, B. K. ^[1]; Xin, Y. ^[2]; Ridge, C. J.; Lindsay, C. M. ^[3]; Buszek, R. J. ^[4]; Boatz, J. A. ^[5]; Boyle, J. M. ^[6]

---

1. University of Dayton Research Institute, 300 College Park, Dayton, Ohio 45469 (United States)
2. National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310 (United States)
3. Air Force Research Laboratory, Munitions Directorate, 2306 Perimeter Rd., Eglin AFB, Florida 32542 (United States)
4. ERC Inc., Edwards AFB, California 93524 (United States)
5. Air Force Research Laboratory, Aerospace System Directorate, Edwards AFB, California 93524 (United States)
6. Naval Surface Warfare Center Indian Head Explosive Ordnance Technology Division, Indian Head, Maryland 20640 (United States)

We demonstrate the ability to produce core-shell nanoclusters of materials that typically undergo intermetallic reactions using helium droplet mediated deposition. Composite structures of magnesium and copper were produced by sequential condensation of metal vapors inside the 0.4 K helium droplet baths and then gently deposited onto a substrate for analysis. Upon deposition, the individual clusters, with diameters ∼5 nm, form a cluster material which was subsequently characterized using scanning and transmission electron microscopies. Results of this analysis reveal the following about the deposited cluster material: it is in the un-alloyed chemical state, it maintains a stable core-shell 5 nm structure at sub-monolayer quantities, and it aggregates into unreacted structures of ∼75 nm during further deposition. Surprisingly, high angle annular dark field scanning transmission electron microscopy images revealed that the copper appears to displace the magnesium at the core of the composite cluster despite magnesium being the initially condensed species within the droplet. This phenomenon was studied further using preliminary density functional theory which revealed that copper atoms, when added sequentially to magnesium clusters, penetrate into the magnesium cores.

• OSTI ID: 22416180
• Journal Information: Journal of Chemical Physics, Vol. 142, Issue 8; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CHEMICAL STATE
COPPER
COPPER ALLOYS
DENSITY FUNCTIONAL METHOD
DEPOSITION
DROPLETS
HELIUM
MAGNESIUM
MAGNESIUM ALLOYS
NANOSTRUCTURES
SUBSTRATES
TRANSMISSION ELECTRON MICROSCOPY
VAPORS