Browsing by Author "Ionescu, M"
Now showing 1 - 20 of 100
Results Per Page
Sort Options
- ItemAnodic behavior of zinc in Zn-MnO2 battery using ERDA technique(Elsevier, 2010-07) Minakshi, M; Ionescu, MThe commercial, alkaline zinc-manganese dioxide (Zn-MnO2) primary battery has been transformed into a secondary battery using lithium hydroxide electrolyte. Galvanostatic discharge–charge experiments showed that the capacity decline of the Zn-MnO2 battery is not caused by the MnO2 cathode, but by the zinc anode. The electrochemical data indicated that a rechargeable battery made of porous zinc anode can have a larger discharge capacity of 220 mAh/g than a planar zinc anode of 130 mAh/g. The cycling performance of these two anodes is demonstrated. Structural and depth profile analyses of the discharged anodes are examined by X-ray diffraction (XRD) and elastic recoil detection analysis (ERDA) techniques. © 2010, Elsevier Ltd.
- 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, DB; 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.
- ItemAntimicrobial and anti-Inflammatory gallium Implanted ‘trojan Horse’ surfaces for implantable devices(Australian Nuclear Science and Technology Organisation, 2021-11-23) Divakarla, SK; Das, T; Chatterjee, C; Ionescu, M; Pastuovic, Z; Jang, JH; Alkhoury, H; Loppnow, H; Yamaguchi, S; Groth, T; Chrzanowski, WA rapidly aging population, high incidence of osteoporosis and trauma-related fractures, and better health care access explain rapid surge in utilisation of orthopedic implantable devices. Unfortunately, many implants fail without strategies that synergistically prevent infections and enhance the implant’s integration with host tissues. Here, we propose a solution that builds on our pioneering work on gallium (Ga)-enhanced biomaterials, which show exceptional antimicrobial activity, and combined it with defensin (De, hBD-1), which has potent anti-microbial activity in vivo as part of the innate immune system. Our aim was to simultaneously impart antimicrobial activity and anti-inflammatory properties to polymer-based implantable devices through the modification of the surfaces with Ga ions and immobilisation of De. Poly-lactic acid (PLA) films were modified using Ga implantation using the Surface Engineering Beamline of the 6MV SIRIUS tandem accelerator at ANSTO Australia, and subsequently functionalised with De. Ga ion implantation increased surface roughness and increased stiffness of treated PLA surfaces and led to the reduction in foreign body giant cell formation and expression of pro-inflammatory cytokine IL-1β. Ga implantation and defensin immobilization both independently and synergistically introduced antimicrobial activity to the surfaces, significantly reducing total live biomass. We demonstrated, for the first time, that antimicrobial effects of De were enhanced by its surface immobilization. Cumulatively, the Ga-De surfaces were able to kill bacteria and reduce inflammation in comparison to the untreated control. These innovative surfaces have the potential to prevent biofilm formation without inducing cellular toxicity or inflammation, which is essential in enhancing integration of implantable devices with host tissues and hence, ensure their longevity. © The Authors
- ItemA bright future for accelerator science at ANSTO(Australian Institute of Nuclear Science and Engineering (AINSE), 2009-11-25) Hotchkis, MAC; Child, DP; Cohen, DD; Dodson, JR; Fink, D; Garton, DB; Hua, Q; Ionescu, M; Jacobsen, GE; Levchenko, VA; Mifsud, C; Siegele, R; Smith, AM; Williams, AG; Winkler, SIn the May 2009 budget, the Federal Government announced funding of $25m to ANSTO through the Education Investment Fund, to build state-of-the-art applied accelerator science facilities, by upgrading and replacing existing facilities and laboratories at ANSTO. Currently, ANSTO's researchers, jointly with researchers from all 37 Australian universities, plus other agencies such as CSIRO, government departments and local government bodies, and overseas collaborators and customers, use ANSTO's accelerator facilities for analysis of a wide range of materials, predominantly by Accelerator Mass Spectrometry (AMS) and Ion Beam Analysis (IBA). There are >100 external users of those facilities every year. © 2009 AINSE
- ItemCathodic arc co-deposition of highly oriented hexagonal Ti and Ti2AlC MAX phase thin films(Elsevier, 2009-08-25) Guenette, MC; Tucker, MD; Ionescu, M; Bilek, MMM; McKenzie, DRTi2AlC belongs to a family of ternary nanolaminate alloys known as the MAX phases, which exhibit a unique combination of metallic and ceramic properties. Here we report pulsed cathodic arc deposition of c axis normal oriented Ti2AlC thin films on α-Al2O3 (001) single crystal substrates heated to 900°C, without an intentionally pre-deposited seed layer. Oriented hexagonal Ti is observed in some films and an in-plane epitaxial relationship between the α-Al2O3 (001) substrate, the hexagonal Ti and Ti2AlC MAX phase is observed. We observe formation of the Ti2AlC phase in all films despite variations in elemental composition. The electrical resistivity of our films was in the range 0.48–0.67 μΩ m, higher than other values found for Ti2AlC in the literature. © Elsevier B.V.
- ItemThe Centre for Accelerator Science at ANSTO(International Atomic Energy Agency, 2014-01-14) Hotchkis, MAC; Child, DP; Cohen, DD; Dodson, JR; Fink, D; Fujioka, T; Garton, DB; Hua, Q; Ionescu, M; Jacobsen, GE; Levchenko, VA; Mifsud, C; Pastuovic, Z; Siegele, R; Smith, AM; Wilcken, KM; Williams, AGIn 2009, the Federal government provided funding of $25m to ANSTO through the Education Investment Fund, to build state-of-the-art applied accelerator science facilities, with the primary aim of providing world-leading accelerator mass spectrometry (AMS) and ion beam analysis (IBA) facilities. New buildings are now under construction and Building plans are now well advanced, and two new accelerators are on order with National Electrostatics Corporation, USA. The 1MV AMS accelerator system is designed with the capability to perform high efficiency, high precision AMS analysis across the full mass range. Large beam-optical acceptance will ensure high quality and high throughput radiocarbon measurements. High mass resolution analyzers, at low and high energy, coupled to a novel fast isotope switching system, will enable high quality analysis of actinide radioisotopes. The 6MV tandem accelerator will be instrumented with a wide range of AMS, IBA and ion irradiation facilities. The three ion sources include hydrogen and helium sources, and a MCSNICS sputter source for solid materials. The AMS facility has end stations for (i) a gasabsorber detector for 10Be analysis, (ii) a time-of-flight detector, (iii) a gas-filled magnet and(iv) a general use ionization detector suited to 36Cl and other analyses. Initially, there will be four IBA beamlines, including a new ion beam microprobe currently on order with Oxford Microbeams. The other beamlines will include an on-line ion implanter, nuclear reaction analysis and elastic recoil detection analysis facilities. The beam hall layout allows for future expansion, including the possibility of porting the beam to the existing ANTARES beam hall for simultaneous irradiation experiments.Two buildings are currently under construction, one for the new accelerators and the other for new chemistry laboratories for AMS and mass spectrometry facilities. The AMS chemistry labs are planned in two stages, with the new radiocarbon labs to come in the second phase of work.
- ItemCharacterisation of a ΔE–E particle telescope using the ANSTO heavy ion microprobe(Elsevier, 2007-07) Siegele, R; Reinhard, MI; Prokopovich, DA; Ionescu, M; Cohen, DD; Rosenfeld, AB; Cornelius, IM; Wroe, A; Lerch, MLF; Fazzi, A; Pola, A; Agosteo, SSemiconductor planar processing technology has spurned the development of novel radiation detectors with applications in space, high energy physics, medical diagnostics, radiation protection and cancer therapy. The ANSTO heavy ion microprobe, which allows a wide range of ions to be focused into spot sizes of a few micrometers in diameter, has proven to be an essential tool for characterising these detectors using the Ion Beam Induced Charge (IBIC) imaging technique. The use of different ions and the wide range of available energies on the heavy ion microprobe, allows the testing of these devices with ionising particles associated with different values of linear energy transfer (LET). Quadruple coincidence measurements have been used to map the charge collection characteristics of a monolithic ΔE-E telescope, This was done through simultaneous measurement of the spatial coordinates of the microbeam relative to the sample and the response of both detector elements. The resulting charge collection maps were used to better understand the functionality of the device as well as to ascertain ways in which future device designs could be modified to improve performance. © 2007, Elsevier Ltd.
- ItemCharacterisation of methane plasma treated carbon surfaces(Institute of Electrical and Electronics Engineers, 2008-02-25) Deslandes, A; Jasieniak, M; Ionescu, M; Shapter, JG; Quinton, JSTime of Flight Secondary ion Mass Spectrometry (ToF-SIMS) was used to investigate the chemical nature of methane plasma treated graphite surfaces. Principle Component Analysis (PCA) was applied to the SIMS data, revealing chemical changes to the surfaces, in particular the extent of hydrogenation. The hydrogen content of the HOPG surface is observed to increase with systematic increases in power of the plasma treatment. These results are supported by Elastic Recoil Detection Analysis (ERDA) measurements that show a similar increase in hydrogen content. Scanning Tunneling Microscopy (STM) measurements provide insight into the morphological changes to the surface caused by the treatment, via investigating plasma-created features that are observed to increase in coverage with the increases in plasma power. © 2008 IEEE.
- ItemA comparative study of two nanoindentation approaches for assessing mechanical properties of ion-irradiated stainless steel(The Minerals, Metals & Materials Society, 2020-02-26) Bhattacharyya, D; Saleh, M; Xu, A; Zaidi, Z; Hurt, C; Ionescu, MNot available
- ItemControl of time-dependent buckling patterns in thin confined elastomer film(Materials Research Society, 2010-10) Winton, BR; Ionescu, M; Dou, SXLow energy metal ion implantation has been used to combine an easy “bottom-up” way of creating and tuning different topographic structures on submicron to micrometer scales with the embedding of a metallic element-rich functionalized layer at the surface for a variety of scientific and technological applications. The self-organizing and complex patterns of functionalized topographic structures are highly dependent on the implanted metal ion species, variations in the geometric confinement of the buckled areas on the larger unmodified elastomer film, and the boundary conditions of the buckled regions. Systematic investigations of these dependencies have been carried out via optical and atomic force microscopy, and confirmed with cross-sectional transmission electron microscopy. © 2010, Materials Research Society
- ItemCurrent advances on titanate glass-ceramic composite materials as waste forms for actinide immobilization: a technical review(Elsevier, 2022-05) Zhang, YJ; Kong, L; Ionescu, M; Gregg, DJAs the emerging versatile waste forms for immobilizing actinide-rich radioactive wastes, glass-ceramic composite materials based on some durable ceramic phases are being developed. They have apparent advantages over the conventional borosilicate glasses and multi- or single- phase ceramics as they essentially combine the chemical and processing flexibilities of glasses to accommodate processing impurities and excellent chemical durability of ceramic phases to host actinides. More recently, some new advances have been made on scientific and technological aspects including new glass-ceramic systems; improved understanding of ceramic phase evolution in glass; actinide validation studies and simplified processing techniques. This review is intended to cover the current advances on the development of glass-ceramic composite waste forms focusing on titanate ceramic phases (zirconolite, pyrochlore and brannerite) for immobilizing various actinide-rich radioactive wastes arising from the nuclear fuel cycle. © 2021 Published by Elsevier Ltd.
- ItemDepth control of ferromagnetism in FePt3 films by ion-irradiation(International Conference on Neutron Scattering, 2017-07-12) Causer, GL; Cortie, DL; Zhu, HL; Ionescu, M; Mankey, GJ; Klose, FThe roadmap which outlines storage technology of magnetic hard disk drives predicts storage densities above 5 Tb/in2 to be realised by isolated, individually addressable ferromagnetic (FM) bits of <10 nm in lateral dimension. In principle, artificially patterned structures of this type can be manufactured by x-ray, ion-and electron-beam lithography. However, there may be alternative solutions for obtaining these regular, nanoscale patterns of isolated FM dots. Our proposal is to locally transform a non-magnetic layer into a pattern of geometrically defined FM islands. Such a phase transition could be initiated by locally changing some physical parameter of the layer, such as its strain state or chemical composition leading to ferromagnetism. Here, we present a chemical order (paramagnetic) to chemical disorder (FM) phase transition stimulated by He+ irradiation of a FePt3 thin film. This talk will present preliminary work focussing on depth profiling the ion-beam induced FM order. By controlling the energy (15 keV) and fluence (2x1016 ions/cm2) of the ion-beam, we show ferromagnetism can be locally induced into the upper-half volume of the initially chemically well-ordered 280 nm FePt3 film. Polarised neutron reflectometry was used to investigate the depth dependence of the layer averaged ion-beam induced FM moment within the thin film. Data analysis of the Kiessig fringes observed in the reflectivity post-irradiation suggest the FM / nonmagnetic interface is atomically sharp. The resulting bilayer structure was found to be homogenous in chemical composition but heterogeneous in both chemical and magnetic orders.
- ItemDepth-profiling magnetic interfaces formed intrinsically in FePt3 by ion-beams(American Physical Society, 2018-03-07) Causer, GL; Cortie, DL; Zhu, HL; Ionescu, M; Mankey, GJ; Wang, XL; Klose, FUsing ion-beams to locally modify material properties is rapidly gaining momentum as a technique of choice for the fabrication of magnetic nano-elements because the method provides the capability to nano-engineer in 3D, which is important for many future spintronic technologies. The precise definition of the resulting element shape is crucial for device functionality. In this work, the intrinsic sharpness of a magnetic interface formed by nano-machining FePt3 films using He+ irradiation is investigated. Through careful selection of the irradiating ion’s energy and fluence, ferromagnetism is locally induced into a fractional volume of a paramagnetic (PM) FePt3 film by modifying the chemical order parameter. Using a combination of magnetometry, transmission electron microscopy and polarised neutron reflectometry it is demonstrated that the interface over which the PM to ferromagnetic modulation occurs is confined to a few atomic monolayers only. Using density functional theory, the mechanism for the ion-beam induced magnetic transition is elucidated and shown to be caused by an intermixing of Fe and Pt atoms in anti-site defects above a threshold density.
- ItemDevelopment of accelerator based micro IBA techniques for the study of environmental samples and material characterisation(Australian Nuclear Science and Technology Organisation, 2010-05-17) Cohen, DD; Siegele, R; Stelcer, E; Ionescu, M; Garton, DBThe Australian Nuclear Science and Technology Organisation (ANSTO) is a research establishment of around 950 people located approximately 30 km south west of Sydney, Australia. ANSTO has several research institutes, including Bragg, Radiopharm, Materials and Environment. These institutes alone include about 300 research and technical support staff. ANSTO's major neutron facility is the Open Pool Australian Light Water Reactor (OPAL). It is a 20 MW pool reactor using low enriched uranium fuel, and cooled by water. It is a multipurpose facility for radioisotope production, irradiation services and neutron beam research.
- ItemDevelopment of advanced diluted magnetic semiconductors with rare earth doping technology(University of Western Australia, 2007-10-15) Photongkam, P; Ionescu, M; Zeng, R; Yu, DH; Li, S
- ItemDirect measurement of the intrinsic sharpness of magnetic interfaces formed by chemical disorder using a He+ beam(American Chemical Society, 2018-04-27) Causer, GL; Cortie, DL; Zhu, H; Ionescu, M; Mankey, GJ; Wang, XL; Klose, FUsing ion beams to locally modify material properties and subsequently drive magnetic phase transitions is rapidly gaining momentum as the technique of choice for the fabrication of magnetic nanoelements. This is because the method provides the capability to engineer in three dimensions on the nanometer length scale. This will be an important consideration for several emerging magnetic technologies (e.g., spintronic devices and racetrack and random-access memories) where device functionality will hinge on the spatial definition of the incorporated magnetic nanoelements. In this work, the fundamental sharpness of a magnetic interface formed by nanomachining FePt3 films using He+ irradiation is investigated. Through careful selection of the irradiating ion energy and fluence, room-temperature ferromagnetism is locally induced into a fractional volume of a paramagnetic (PM) FePt3 film by modifying the chemical order parameter. A combination of transmission electron microscopy, magnetometry, and polarized neutron reflectometry measurements demonstrates that the interface over which the PM-to-ferromagnetic modulation occurs in this model system is confined to a few atomic monolayers only, while the structural boundary transition is less well-defined. Using complementary density functional theory, the mechanism for the ion-beam-induced magnetic transition is elucidated and shown to be caused by an intermixing of Fe and Pt atoms in antisite defects above a threshold density. © 2018 American Chemical Society.
- ItemDLC coatings: effects of physical and chemical properties on biological response(Elsevier, 2007-03) Ma, WJ; Ruys, AJ; Mason, RS; Martin, PJ; Bendavid, A; Liu, ZW; Zreiqat, H; Ionescu, MRecent trials on diamond-like carbon (DLC) coated medical devices have indicated promise for blood interfacing applications. The literature is sparse regarding structural and compositional effects of DLC on cellular response. An important goal in optimizing blood-interfacing implants is minimal macrophage attachment, and maximal albumin:fibrinogen adsorption ratio. DLC coatings deposited by PACVD and FAD, were analysed with respect to sp(3) content (EELS), hydrogen content (ERDA), surface composition (XPS), surface roughness (AFM), surface energy, albumin: fibrinogen adsorption ratio, and macrophage viability and attachment. We found that increasing surface roughness and surface energy enhanced the macrophage viability and the albumin: fibrinogen adsorption ratio. We also found that the higher the hydrogen content for a-C:Hs deposited by PACVD, the lower the albumin:fibrinogen adsorption ratio, and macrophage attachment. This suggests that hydrogen content may be an important factor for influencing the biological response of DLC surfaces. Macrophage cells spread well on all DLC surfaces, and the surface results indicated the non-toxic nature of the surfaces on the cells at the time points tested. © 2007, Elsevier Ltd.
- ItemDoiba manual: using PIXE and PIGE to their full potential with doiba(Australian Nuclear Science and Technology Organisation, 2008-04) Siegele, R; Ionescu, M; Cohen, DDIn the early 1980s, Eric Clayton developed a software package for the analysis of Proton Induced X-Ray Emission (PIXE) spectra at the Australian Nuclear Science and Technology Organisation (ANSTO). This package was called PIXAN and it is based on work by D.D. Cohen et al. and E. Clayton et al. The package is optimised for the batch analysis of a large number of similar samples. It uses a 2 step process to analyse PIXE spectra. Command line programs controlled by run control files that contain the parameters of the experiment facilitate the 2 steps of the analysis.
- ItemDoping of ZnO thin film with Eu using ion beams(Trans Tech Publications, 2010-01-01) Ionescu, M; Photongkam, P; Yu, DH; Siegele, R; Li, S; Cohen, DDModification of electric and magnetic properties of ZnO thin films was achieved by low energy Eu ion irradiation. The desired doping levels as well as the depth distribution of the dopant was controlled by the ion energy and the ion flux, following a simulated interaction between the doping ion and the host ZnO matrix of epitaxial ZnO (0001) films of approximatelly 200nm, grown on c-Al2O3 by PLD. The properties of the doped ZnO film depend in a critical way on the homogeneity of the doped ions throughout the entire film. The doping levels and the depth distribution of dopants were measured by elastic recoil detection analysis (ERDA). The results show a uniform depth distribution of Eu, as well as some level of Al diffusion from the substrate and the presence of some low levels of H, N and O. PACS code: 68.49Sf; 74.78Bz.
- ItemEffect of annealing upon retention of He and H in irradiated SiC(Trans Tech Publications, 2017) Ionescu, M; Deslandes, A; Holmes, R; Guenette, MC; Karatchevtseva, I; Lumpkin, GRSilicon carbide (3C-β SiC) samples were irradiated with He ions of energy up to 30 keV and a fluence up to 1016/cm2, to produce damage in the near-surface region. A duplicate set of He ion irradiated SiC samples, as well as undamaged SiC, were also irradiated with H2+ ions of energy up to 20 keV and a similar fluence, to study the interaction of H species with pristine SiC and with He radiation-damaged SiC. Samples were annealed in steps of 200 K, from 473 K to 1273 K, and the retention of H and He were measured using elastic recoil detection analysis with 7.8 MeV C3+ ions, after each anneal step. Modification to the surface following irradiation is observed via Raman spectroscopy, which exhibits development of damage states such as disordered carbon and Si-Si peaks. Only minor changes in the H and He profiles were observed up to 1073 K, however after the 1273 K anneal the H and He profiles changed considerably, with a marked difference between samples irradiated only with He and those irradiated with He and H. © 2025 Trans Tech Publications Ltd