Browsing by Author "Metson, JB"

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    Ion beam analysis of GdN thin films with a protective GaN capping layer
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2005-11-20) Granville, S; Budde, F; Koo, A; Ruck, BJ; Trodahl, HJ; Bittar, A; Metson, JB; Kennedy, VJ; Prince, KE; Atanacio, AJ
    Rare-earth nitrides represent an interesting class of matrials that exhibit a range of electronic and magnetic properties. Recent LSD+SIC calculations have predicted magnetic properties covering paramagnetic, ferromagnetic, and antiferromagnetic, and elecronic states including metallic, semiconducting, or insulating, and a number exhibit half-metallicity. Due to this wide variety of predicted properties these materials are of considerable interest as potential sources of spin-polarised current for novel devices. Although numerous studies of the rare-earth nitrides are present in the literature, there is still much to be learned about them. The most well studied of these nitrides is GdN, a ferromagnet with the highest Curie temperature of the series. The magnetic properties in particular have been extensively studied, but often the presence of impurities such as O could not be ruled out, and studies have shown that N vacancies or O impurities significantly influence the magnetic quality of GdN. The rare-earth nitrides are sensitive to water vapour and react rapidly upon exposure to atmosphere, so it is an ongoing challenge to produce GdN of a sufficient purity to make characterising its properties an achievable task. In particular the electrical and optical properties of stoichiometric GdN have not both been established reliably, despite their great relevance to the potential usefulness of the material in devices.
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    Phase-oriented surface segregation in an aluminium casting alloy
    (Elsevier, 2009-02-15) Nguyen, CL; Atanacio, AJ; Zhang, W; Prince, KE; Hyland, MM; Metson, JB
    There have been many reports of the surface segregation of minor elements, especially Mg, into surface layers and oxide films on the surface of Al alloys. LM6 casting alloy (Al–12%Si) represents a challenging system to examine such segregation as the alloy features a particularly inhomogeneous phase structure. The very low but mobile Mg content (approximately 0.001 wt.%), and the surface segregation of modifiers such as Na, mean the surface composition responds in a complex manner to thermal treatment conditions. X-ray photoelectron spectroscopy (XPS) has been used to determine the distribution of these elements within the oxide film. Further investigation by dynamic secondary ion mass spectrometry (DSIMS) confirmed a strong alignment of segregated Na and Mg into distinct phases of the structure. © 2009, Elsevier Ltd.