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Direct observation of spinlike reaction fronts in planar energetic multilayer foils

Applied Physics Letters

McDonald, Joel P.; Hodges, Vernon C.; Jones, E.D.; Adams, David P.

Propagating reactions in initially planar cobalt/aluminum exothermic multilayer foils have been investigated using high-speed digital photography. Real-time observations of reactions indicate that unsteady (spinlike) reaction propagation leads to the formation of highly periodic surface morphologies with length scales ranging from 1 μm to 1 mm. The characteristics of propagating spinlike reactions and corresponding reacted foil morphologies depend on the bilayer thickness of multilayer foils. © 2009 American Institute of Physics.

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TYPE Journal Article YEAR 2009
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Unsteady reaction behaviors in reactive Co/Al multilayer foils

Materials Research Society Symposium Proceedings

McDonald, Joel P.; Jones, E.D.; Hodges, Vernon C.; Adams, David P.

Reaction dynamics in exothermic Co/Al multilayer foils are studied with high speed digital photography. Unsteady, spin-like reaction propagation is observed in which the net synthesis of a foil is accomplished through advancing transverse bands that propagate perpendicular to the net reaction direction. This unsteady behavior is connected to the final reacted foil surface morphology that exhibits periodic structures. The evolution of the reaction front shape and corresponding surface morphology are discussed with respect to Co/Al foil characteristics. © 2009 Materials Research Society.

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TYPE Conference YEAR 2008
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Low temperature photoluminescence studies of narrow bandgap GaAsSbN quantum wells on GaAs

Materials Research Society Symposium - Proceedings

Waldrip, Karen E.; Jones, E.D.; Modine, N.A.; Jalali, F.; Klem, John F.; Peake, G.M.

We present low-temperature (T = 4K) photoluminescence studies of the effect of adding nitrogen to 6-nm-wide single-strained GaAsSb quantum wells on GaAs. The samples were grown by both MBE and MOCVD techniques. The nominal Sb concentration is about 30%. Adding about 1 to 2% N drastically reduced the bandgap energies from 1 to 0.75 eV, or 1.20 to 1.64 μm. Upon performing ex situ rapid thermal anneals, 825°C for 10s, the band gap energies as well as the photoluminescence intensities increased. The intensities increased by an order of magnitude for the annealed samples and the band gap energies increased by about 50 - 100 meV, depending on growth temperatures. The photoluminescence linewidths tended to decrease upon annealing. Preliminary results of a first-principles band structure calculation for the GaAsSbN system are also presented.

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TYPE Conference YEAR 2002
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23 Results
23 Results