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Harker S.J.,Defence Science and Technology Organisation, Australia | Harker S.J.,UNSW Canberra at the Australian Defence Force Academy | Stewart G.A.,UNSW Canberra at the Australian Defence Force Academy | Hutchison W.D.,UNSW Canberra at the Australian Defence Force Academy | And 2 more authors.
Hyperfine Interactions | Year: 2015

The impact of doping the Fe component of barium hexaferrite with Ni0.5Ti0.5 is investigated using x-ray powder diffraction, 57Fe Mössbauer spectroscopy and microwave network analysis. The dopant ions exhibit a preference for the 2b, 4f2 and 12k-sites and the unit cell volume is observed to decrease. The ferromagnetic resonance frequency is reduced by about 11.5 GHz for each additional dopant ion per formula unit. © 2015, Springer International Publishing Switzerland.

Bali M.S.,UNSW Canberra at the Australian Defence Force Academy | Armitt D.,Defence Science and Technology Organisation, Australia | Wallace L.,UNSW Canberra at the Australian Defence Force Academy | Day A.I.,UNSW Canberra at the Australian Defence Force Academy
Journal of Forensic Sciences | Year: 2014

Research to counter the threat of organic peroxides such as triacetone triperoxide (TATP) is at times hampered by their inherent extreme sensitiveness and volatility. This work describes an approach to lowering some risks associated with the handling of TATP in the laboratory through the use of an analog species, tripentanone triperoxide (TPTP). Sensitiveness has been tested via standard methods. GCMS analysis has shown that TPTP degrades via similar mechanisms to TATP under a range of conditions. Slight differences in product composition were traced to side reactions which may also affect impurities present in homemade TATP synthesis. A pilot field trial was conducted to evaluate TPTP as a substitute for TATP in explosive detection dog (EDD) scent training. The degradation studies have yielded insights into the complexities of the acidic degradation of cyclic peroxides with potential forensic application, and TPTP's inadequacy as a TATP pseudoscent is a valuable example of the limitations of such training aids. © 2014 American Academy of Forensic Sciences.

Lashgari H.R.,University of New South Wales | Cadogan J.M.,UNSW Canberra at the Australian Defence Force Academy | Chu D.,University of New South Wales | Li S.,University of New South Wales
Materials and Design | Year: 2016

In this study we investigate the mechanical properties of Fe80.75Si8B11.25 amorphous alloys produced by melt-spinning by means of single-step and multi-step nanoindentation methods. Single-step nanoindentation showed that annealing treatment increases the hardness (by ≈13%) and Young's modulus (by ≈46%); however, unnecessary prolonged annealing time (500°C for 3h) decreases the hardness (by ≈20%) and Young's modulus (by ≈16%) considerably. Positron annihilation spectroscopy (PALS) showed two lifetime components corresponding to the interstitial defects and free volume, the lifetime of both decreased after stress-relaxation treatment at temperature far below the glass transition point. The strain hardening behaviour was observed during multi-step nanoindentation in amorphous state leading to a slight increase of hardness (≈5%); however, multi-step nanoindentation in the stress-relaxed sample (400°C for 0.5h) resulted in an overall strain-softening phenomenon and any increase in the number of cycles (from 3 to 10) did not alter the global softening behaviour. Atomic force microscopy (AFM) of the indented surface in the amorphous sample revealed the strain localization around the residual indent after multi-step nanoindentation (leading to more material pile-up as compared to single-step indent) that could be due to the densification induced by stress and/or interaction and entanglement of the shear bands during unloading/reloading process. © 2015 Elsevier Ltd.

Cadogan J.M.,UNSW Canberra at the Australian Defence Force Academy | Ryan D.H.,McGill University | Rejali R.,McGill University | Boyer C.D.,Chalk River Laboratories
Journal of Alloys and Compounds | Year: 2016

The magnetic ordering of the trigonal compound EuGe2 has been studied using 151Eu Mössbauer spectroscopy and neutron powder diffraction. The europium in EuGe2 is divalent and orders antiferromagnetically (AF) below TN∼49 K giving a hyperfine field of 24.4(1) T at 4.6 K. The thermal evolution of the spectra shows no evidence for changes to the structure or slow paramagnetic dynamics as TN is approached from below. Analysis of the neutron diffraction data shows that EuGe2 orders as an A-type AF with the 7.1(2)μB Eu2+ moments ordered as ferromagnetic sheets within the ab-plane and AF coupled along the c-axis, forming a magnetic cell that is doubled along the crystallographic c-axis. © 2016 Elsevier B.V.

Ryan D.H.,McGill University | Cadogan J.M.,UNSW Canberra at the Australian Defence Force Academy
Hyperfine Interactions | Year: 2014

The closed-shell, well-screened europium moment should make its compounds an easy and robust system in which to study the correlation between the local moment and the observed hyperfine field (Bhf). Having explored why one might expect Bhf to provide a reasonable measure of the local moment, and why the isomer shift (δ) might allow for a first-order correction to include the effects of the local chemical environment, we proceed with an anlysis of the extensive 151Eu Mössbauer data on the EuT2X2 compound family. We find that while in some limited cases a useful correlation may exist, in general there are far too many as yet unknown contributions to Bhf for it to provide a meaningful estimate of the moment. © 2013 Springer Science+Business Media Dordrecht.

Ryan D.H.,McGill University | Legros A.,McGill University | Niehaus O.,University of Munster | Pottgen R.,University of Munster | And 2 more authors.
Journal of Applied Physics | Year: 2015

Neutron powder diffraction confirms that the primary ordering mode in Eu4PdMg is ferromagnetic with a europium moment of 6.5(2) μB. 151Eu Mössbauer spectroscopy shows that the unusual linear temperature dependence of the magnetisation reported for this system is an intrinsic property and not an artefact of the applied field. The form and temperature evolution of the 151Eu Mössbauer spectra strongly suggest that there is an incommensurate modulation to the magnetic structure that modifies the basic ferromagnetic order. This modulated structure may be the origin of the broad magnetocaloric response previously observed in Eu4PdMg. © 2015 AIP Publishing LLC.

Diop L.V.B.,CNRS Neel Institute | Isnard O.,CNRS Neel Institute | Lee-Hone N.R.,McGill University | Ryan D.H.,McGill University | Cadogan J.M.,UNSW Canberra at the Australian Defence Force Academy
Journal of Physics Condensed Matter | Year: 2013

The effects of iron substitution on the structural and magnetic properties of the GdCo12-xFexB6 (0 ≤ x ≤ 3) series of compounds have been studied. All of the compounds form in the rhombohedral SrNi12B6-type structure and exhibit ferrimagnetic behaviour below room temperature: TC decreases from 158 K for x = 0 to 93 K for x = 3. 155Gd Mössbauer spectroscopy indicates that the easy magnetization axis changes from axial to basal-plane upon substitution of Fe for Co. This observation has been confirmed using neutron powder diffraction. The axial to basal-plane transition is remarkably sensitive to the Fe content and comparison with earlier 57Fe-doping studies suggests that the boundary lies below x = 0.1. © 2013 IOP Publishing Ltd.

Cadogan J.M.,UNSW Canberra at the Australian Defence Force Academy | Devlin E.J.,Advanced Materials and Processes
Hyperfine Interactions | Year: 2014

Nurina-003 is a Group LL5/br Ordinary Chondrite meteorite which was recovered in the Nullarbor Desert (Australia) in 1986. The degree of weathering is classified as moderate to severe. We have characterised the Fe-bearing phases in Nurina-003 by 57Fe Mössbauer Spectroscopy over the temperature range 5-295 K. The spectra are dominated by Olivine and also contain Pyroxene, Troilite and a Ferric component that is (super)paramagnetic at 295 K. We clearly see the effects of the magnetic ordering of the Olivine phase in the 5 K spectrum. © 2013 Springer Science+Business Media Dordrecht.

Hynes M.,Australian National University | Sharpe S.,UNSW Canberra at the Australian Defence Force Academy
Cultural Geographies | Year: 2015

Contributing to cultural geography’s emerging interest in the work of Felix Ravaisson, this article explores the relationship between the impersonal force of habit and the personalised production of subjectivity. More precisely, our concern is with the relationship between habit and the stylisation of self that can be witnessed in the production of the intellectual subject. Paying particular attention to the relationship he traces between habit, consciousness and the effort that defines subjectivity, we explore the implications of Ravaisson’s understanding of habit for the work of style, understood as an integration of habits and dispositions into a manner of being. By exploring the question of intellectual style in the work of Alain Badiou, Michel Foucault and Friedrich Nietzsche, we consider what the implications might be of performing that task of integration lightly, without the lofty weightiness that often attends intellectual life. © The Author(s) 2014.

Susilo R.A.,UNSW Canberra at the Australian Defence Force Academy | Cadogan J.M.,UNSW Canberra at the Australian Defence Force Academy | Hutchison W.D.,UNSW Canberra at the Australian Defence Force Academy | Campbell S.J.,UNSW Canberra at the Australian Defence Force Academy
Physica Status Solidi (A) Applications and Materials Science | Year: 2014

The intrinsic magnetism of Gd2Fe2Si2C has been investigated using magnetization and specific heat measurements. Gd 2Fe2Si2C orders magnetically below 58 K, consistent with the de Gennes scaling observed for the remaining (heavy-R) R2Fe2Si2C compounds.A second magnetic event at ∼38 K is also observed in the susceptibility and specific heat data which might signal a spin-reorientation transition. Field dependent magnetometry suggests that the magnetic structure of this compound is quite complex. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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