Browsing by Author "Prior, MJ"
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- ItemANSTO heavy ion ToF for analysis of light elements in thin films(Australian Institute of Nuclear Science and Engineering (AINSE), 2007-11) Ionescu, M; Zhao, Y; Siegele, R; Cohen, DD; Lynch, D; Garton, D; Stelcer, E; Prior, MJThin films have various potential applications in electronic devices, and their performance is intricately linked with the electric and magnetic properties of the film, in which an important role is played by the presence of light elements, in particular Hydrogen, Oxygen and Nitrogen. The source of light elements, the form in which they are incorporated into the thin film, and how this is influencing the MgB2 thin film properties is currently under scrutiny by various research groups. Typically these films are grown on oxide ceramic substrates, such as Al2O3-C and it is possible that the source of Oxygen is the substrate itself or the growth atmosphere. Here we report on a study of light elements in MgB2 thin films grown on various substrates, using heavy ions recoil and a time-of-flight detector. A series of MgB2 thin film samples produced by PLD (pulsed laser deposition) were analyzed, including films produced in-situ on Al2O3-C substrates with an on-axis and off-axis geometry, one film produced in-situ with an off-axis geometry, and one film produced ex-situ, with a bulk-like Tc. We also analyzed one film produced with on-axis geometry under the same conditions on Si (001) substrate. The amount of Oxygen detected by ToF, appears to be correlated with the Tc of the films, the higher the Tc the lower the oxygen content. Also, the superconducting properties of the examined thin films are discussed in the context of the results.
- ItemExperimental bremsstrahlung yields for MeV proton bombardment of beryllium and carbon(Elsevier, 2008-04) Cohen, DD; Stelcer, E; Siegele, R; Ionescu, M; Prior, MJExperimental bremsstrahlung yields for 2, 3 and 4 MeV protons on thin beryllium and carbon targets have been measured. The yields have been corrected for detector efficiency, self-absorption in the target and fitted to 9th order polynomials over the X-ray energy range 1-10 keV for easy comparison with theoretical calculations.
- ItemFingerprinting and source apportionment of fine particle pollution in Manila by IBA and PMF techniques: a 7-year study(Wiley-Blackwell, 2009-01) Cohen, DD; Stelcer, E; Santos, FL; Prior, MJ; Thompson, C; Pabroa, PCBX-ray and ion beam analysis (IBA) techniques have been used to characterize fine particle pollution in Manila over a 7-year period. These data have then been used in the latest statistical methods of positive matrix factorization (PMF) to quantitatively identify source fingerprints and their contributions to the total fine particulate mass. © 2008, Wiley-Blackwell.
- ItemHeavy ion ToF analysis of oxygen incorporation in MgB2 thin films(Elsevier, 2008-04) Ionescu, M; Zhao, Y; Siegele, R; Cohen, DD; Stelcer, E; Prior, MJOxygen incorporation in MgB2 thin films during their fabrication process has a strong influence on the future properties of the films, and was studied by Elastic Recoil Detection Analysis with heavy ions and a time-of-flight detection. A series of MgB2 thin film samples were analyzed, including films produced in situ on Al2O3-C and Si (0 0 1) substrates (with higher Tc and lower Tc) with an “on-axis” geometry, and films produced in situ with an “off-axis” geometry. The amount of oxygen detected in these films appears to be correlated with the Tc of the films, the higher the Tc the lower the oxygen content. The superconducting properties of the examined thin films are discussed in the context of the ERDA results. © 2008, Elsevier Ltd.
- ItemIn situ neutron diffraction investigation on the phase transformation sequence of kaolinite and halloysite to mullite(Elsevier B. V., 2006-11-15) Tezuka, N; Low, IM; Davies, IJ; Prior, MJ; Studer, AJ“Kaolin” is a major raw material for the fabrication of conventional ceramics. In this work the authors have investigated the thermal phase transformation of mullite from two different types of kaolin (kaolinite and halloysite), with or without alumina matrix constraint, during heating up to 1500 °C and then cooling using in situ neutron diffraction. Mullitization was initiated upon heating to 1200 °C for all specimens and followed spinel formation at 1100 °C. Above this temperature, however, evolution of the main phases, i.e., mullite, cristobalite and corundum, was influenced by the presence of impurities, initial type of silica, and alumina constraint. The relative amount of mullite was largest for the pure kaolinite specimen, particularly during heating, and this was attributed to the presence of a glassy phase. However, kaolinite with alumina suppressed the crystallization of cristobalite from the glassy phase upon cooling due to a reaction between alumina and amorphous silica, consequently resulting in an amount of mullite as for the pure kaolinite specimen (approximately 65 wt%). Halloysite was less active in terms of mullitization due to the lower level of initial impurities and greater amount of cristobalite, particularly for the alumina-constrained specimen. However, the final amount of mullite derived from the pure halloysite specimen was similar to that as from the kaolinite specimen. Crown Copyright © 2006 Published by Elsevier B.V.
- ItemIn-situ neutron diffraction investigation on the phase transformation sequence of kaolinite and halloysite to mullite(The Bragg Institute, Australian Nuclear Science and Technology Organisation, 2005-11-27) Tezuka, N; Low, IM; Davies, IJ; Prior, MJ; Studer, AJ“Kaolin” is a major raw material for the fabrication of conventional ceramics. Whilst kaolin has been thoroughly studied in the past decades with regards to its application as conventional ceramics there has been renewed interests in the conversion of kaolin to mullite (3Al2O3,2SiO2) with purpose of furthering the understanding of processing advanced ceramics with high strength, toughness, and thermal stability. One of the advantages of kaolin as a starting material is the needle-like morphology of mullite that is obtained by the transformation sequence at elevated temperature: kaolin —> metakaolin —> Al-Si spinel —> primary mullite (2Al203.SiO2) —> secondary mullite (3Al2O3.2SiO2). The ratio of Al203/SiO2 in mullite is considered to change by the replacement of Al and Si atoms in the tetrahedral positions. However, the in-situ transformation of primary to a secondary mullite has not been investigated in detail. This paper investigates the thermal phase transformation of mullite from two different types of kaolin (kaolinite and halloysite) with or without AIZO3 matrix constraint through the heating and cooling process by in-situ neutron diffraction. The effects of starting materials and heat treatment on the mullitisation process, especially in terms of primary —> secondary mullite evolution, are highlighted and discussed. © 2005 The Authors
- ItemIon beam analysis and positive matrix factorisation modeling: tools for exploring aerosol source fingerprints(Australian Institute of Nuclear Science and Engineering (AINSE), 2007-11) Stelcer, E; Cohen, DD; Prior, MJANSTO has been involved in PM2.5 monitoring and analysis since 1991. Long term sampling together with information on concentrations of total collected gravimetric mass, black carbon and 23 elements from hydrogen to lead obtained by accelerator based nuclear analytical methods have been used for generating large data sets. The Positive Matrix Factorisation (PMF) modelling technique has been applied to these data sets for exploring PM2.5 source fingerprints and source contributions at Sydney and Brisbane. Data in this presentation covers sources and their contributions to total PM2.5 at Liverpool (Sydney) from January 1998 to December 2006 and Rocklea (Brisbane) from January 1998 to December 2003.
- ItemMartensite destabilization in Au7Cu5Al4 shape-memory alloy(Elsevier, 2011-03) Bhatia, VK; Kealley, CS; Prior, MJ; Cortie, MBAging-induced changes in the austenite peak (Aρ) temperature of Au7Cu5Al4 shape-memory alloy are investigated. Whereas heat treating the parent phase at temperatures >140°C or aging the martensite for long times at room temperature both stabilized the Aρ to ~80°C, low-temperature excursions into the parent phase caused the subsequent Aρ to drop to ~60°C and the transformation hysteresis to decrease. The evidence indicates that this destabilization of the martensite is caused by time-dependent relaxation of elastic constraint due to parent-phase lath migration during the preceding low-temperature austenitizing treatment. This mechanism of aging is different from that of the better-known symmetry-conforming short-range order phenomenon. © 2011, Elsevier Ltd.
- ItemTowards a better understanding and prediction of the bremsstrahlung background in PIXE spectra(Australian Institute of Nuclear Science and Engineering (AINSE), 2007-11) Cohen, DD; Stelcer, E; Prior, MJ; Siegele, R; Ionescu, MMurozono and Ishii et al recently published theoretical QFEB, SEB and AB bremsstrahlung cross sections which, when modified by typical X-ray detection efficiencies, provide excellent predictions of the backgrounds in PIXE spectra for a range of light target matrices.