skip to main content

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

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.
Authors:
;  [1] ;  [2] ;  [3] ; ;  [4] ;  [5] ;  [6] ;  [7]
  1. University of Dayton Research Institute, 300 College Park, Dayton, Ohio 45469 (United States)
  2. (United States)
  3. National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310 (United States)
  4. Air Force Research Laboratory, Munitions Directorate, 2306 Perimeter Rd., Eglin AFB, Florida 32542 (United States)
  5. ERC Inc., Edwards AFB, California 93524 (United States)
  6. Air Force Research Laboratory, Aerospace System Directorate, Edwards AFB, California 93524 (United States)
  7. Naval Surface Warfare Center Indian Head Explosive Ordnance Technology Division, Indian Head, Maryland 20640 (United States)
Publication Date:
OSTI Identifier:
22416180
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 8; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
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