Browsing by Author "Appadoo, D"

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    40th Annual Condensed Matter and Materials Meeting, Charles Sturt University, Wagga Wagga, NSW, 2nd February – 5th February, 2016
    (Australian Institute of Physics, 2016-02-02) Tadich, A; Brand, HEA; Appadoo, D; Finlayson, TR; James, M
    The 40th Annual Condensed Matter and Materials Meeting was held at Charles Sturt University, Wagga Wagga, NSW from 2 - 5 February, 2016. There were 116 attendees, including international visitors from Scotland, China, Taiwan and New Zealand. A total of 10 invited and 29 contributed oral papers were presented during the two and one half days of scientific sessions. There were also two sessions with a total of 70 poster presentations. All presenters were invited to submit a manuscript (six pages for invited papers and four for contributed papers) for publication in the conference proceedings. Each manuscript was refereed by at least two anonymous reviewers who worked to a set of guidelines made available by the editor. Each accepted publication therefore satisfies the requirements for classification as a refereed conference publication (E1). The organizers would like to thank the reviewers for their time and effort in reviewing manuscripts, which resulted in 10 papers being accepted for publication.
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    Condensed phase studies at the THz/Far-IR beamline at the Australian Synchrotron
    (Australian Institute of Physics, 2014-02-06) Appadoo, D; Ennis, C; Plathe, R
    The THz/Far-IR beamline at the Australian Synchrotron is coupled to a Bruker IFS125HR FT spectrometer equipped with a variety of optical components which can cover the spectral range from 5 to 5000 cm-1. Experiments from a variety of fields such as atmospheric and astrophysical science, geology, electrochemistry, nano-materials as well as biology have been successfully conducted at the beamline. There is a range of instruments to accommodate the diverse requirements of the User community. For gas-phase experiments, the beamline is equipped with multiple-pass optics gas-cells: one of which can be coupled to a furnace to study reactive species, while another can be cooled to liquid nitrogen or helium temperatures to study aerosols and cold gases. Users also have access to a couple of cryostats (one > 79 K, the other > 6 K), a grazing incidence angle optical setup and a near-normal accessory to study condensed phase systems, thin films and surface interactions. The synchrotron infrared light offers a S/N advantage over conventional thermal sources, but this advantage varies to a great degree upon the spectral range, sample size and resolution dictated by the application. In this paper, the capabilities and performance of the THz/Far-IR beamline at the Australian Synchrotron will be presented as well as some applications undertaken at the beamline, and future developments.
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    Estimating dielectric parameters by reflecting evanescent waves at THz frequencies
    (Society of Photo-Optical Instrumentation Engineers (SPIE), 2021-04-20) Vilagosh, Z; Foroughimehr, N; Lajevardipour, A; Appadoo, D; Juodkazis, S; Wood, AW
    The THz/Far-IR Beamline at the Australian Synchrotron was used to demonstrate a novel method of estimating the dielectric properties of homogenous substances in the 1.0 THz to 4.0 THz region. Attenuated total reflection (ATR) coupled with synchrotron sources allow rapid evaluation of samples. The source is incoherent, thus normally only reflectance can be derived, as phase shift data cannot be obtained with this arrangement. A method is presented of deriving the full complex dielectric parameters by a modified frustrated internal reflection technique which reflects the evanescent wave using a gold plated mirror. Oil and alcohol samples were used in the study. With the mirror in situ, the reflectance changed from being enhanced at some frequencies to undergoing a frequency dependent destructive interference at other frequencies. The change in different samples was noted to vary according to the refractive index (but not the absorption coefficient) of the sample. © (2022) Society of Photo-Optical Instrumentation Engineers (SPIE)
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    Growth response of Escherichia coli bacterial cells on exposure to 1.25 Wm-2 synchrotron-sourced Terahertz radiation
    (Institute of Electrical and Electronics Engineers (IEEE), 2023-09-19) Vilagosh, Z; Nguyen, THPP; Perera, PGT; Linklater, D; Appadoo, D; Vingsvivut, JP; Tobin, MJ; Croft, R; Ivanova, EP
    The growth of E. coli cells following low intensity 1.25 Wm−2 broadband synchrotron-sourced Terahertz (THz) radiation was monitored following serial exposures for 60 minutes with distinct samples at 10-minute intervals. After 20 minutes, E. coli cells showed a reduction to 53% compared to the control, and a minor fluctuation in colony forming units density followed by a major recovery to 80% at 60 minutes. © 2023 IEEE.
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    Microstructural and spectroscopic investigations into the effect of CeO2 additions on the performance of a MnO2 aqueous rechargeable battery
    (Elsevier, 2009-04-30) Minakshi, M; Mitchell, DRG; Carter, ML; Appadoo, D; Nallathamby, K
    The influence of CeO2 additions on the electrochemical behaviour of the MnO2 cathode in a Zn–MnO2 battery using lithium hydroxide (LiOH) as an electrolyte is investigated using microscopy and spectroscopic techniques. The results showed that such additions greatly improve the discharge capacity of the battery (from 155 to 190 mAh g−1) but only from the second discharge cycle onwards. Capacity fade with subsequent cycling is also greatly reduced. With an aim to understand the role of CeO2 on the discharge–charge characteristics of MnO2 and its mechanism, we have used a range of microscopy, spectroscopy and diffraction-based techniques to study the process. The CeO2 is not modified by multiple discharged and charged cycles. The CeO2 may enhance the discharge–charge performance of the battery by raising the oxygen evolution potential during charging but does not take part directly in the redox reaction. © 2009, Elsevier Ltd.
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    Neutron and synchrotron characterisation techniques for hydrogen fuel cell materials
    (Australian Nuclear Science and Technology Organisation, 2021-11-24) Lamb, K; Kirby, N; Bartlett, JR; Peterson, VK; Appadoo, D; Jiang, SP; De Marco, R
    Hydrogen fuel cells and other renewable energy technologies have specific materials and functional needs which can be more fully understood using neutron and synchrotron characterisation techniques. In this presentation, a materials which has applications in proton exchange membranes is studied with a variety to techniques to develop a comprehensive understanding of the functional-structural relationship. The materials used here is phosphotungstic acid (HPWA) stabilised in an ‘inert’ mesoporous silica host material. This aim of this research is to develop an understanding of the interaction between the HPWA and the silica and whether different structures or surface chemistries have advantageous or detrimental effects. Two silica symmetries used were Ia3 ̅d (face centred cubic bi-continuous) and P6mm (2D hexagonal with cylindrical pores) which were vacuum impregnated with solutions of HPWA in a range of concentrations. The resulting powder samples were then analysed using small angle x-ray scattering (SAXS), inductively coupled plasma emissions spectroscopy (ICP-OES), nitrogen gas adsorption/desorption, near edge X-ray absorption fine structure (NEXAFS/X-ray absorption near edge structure/XANES) of the O and Si k-edges, Fourier transform infra-red spectroscopy (FTIR), Raman spectroscopy, and then formed into a disk using polyethylene as the binder for electrical impedance spectroscopy (EIS). The insights gained from this systematic study indicate that the surface chemistry of the silica host has a significant effect on the performance, uptake and interactions with the HPWA anions, where lower concentrations of HPWA result in stronger host:HPWA interactions but lower conductivity. © The Authors
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    Sodium for securing future renewable energy supply
    (Australian Institute of Physics, 2016-02-04) Minakshi, M; Appadoo, D
    The storage and recovery of electrical energy is widely recognized as one of the most important areas for energy research. Although renewable energy such as i.e. wind and solar generated electricity is becoming increasingly available in many countries including Australia, these sources provide only intermittent energy. Thus, energy storage systems are required for load levelling, allowing energy to be stored and used on demand. Energy storage in rechargeable batteries and supercapacitors is the most promising prospect for ensuring consistent energy supply therefore allowing greater penetration of renewable energy into the electricity grid. Energy storage capability also has obvious benefits in terms of greenhouse emissions. Issues such as the environment, the rapid increase in fossil fuel prices, and the increased deployment of renewable energy sources, provide a greater need for the development of electrochemical energy storage, especially for large-scale applications. Thus, materials research and computational modelling play a key role in making further progress in the field of energy storage. Energy storage devices based on sodium have been considered as an alternative to traditional lithium based systems because of the natural abundance, cost effectiveness and low environmental impact of sodium. Phosphate materials such as NaNiPO4, NaMnPO4, NaCoPO4 and NaNi1/3Mn1/3Co1/3PO4 will be discussed at the conference. Sodium transition metal phosphate has served as an active electrode material for an energy storage device. The development of sodium transition metal phosphate with special emphasis on structural changes and novel synthetic approach can underpin technological advancements in small renewable energy harvesting and power generation technologies. The characteristics of the fabricated device such as improved storage capability, cycling stability, safety and economic life - cycle cost made this an attractive alternative to conventional charge storage devices using more expensive materials.
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    Structural characteristics of olivine Li(Mg0.5Ni0.5)PO4 via TEM analysis
    (Springer Nature, 2012-01-13) Minakshi, M; Singh, P; Ralph, D; Appadoo, D; Blackford, MG; Ionescu, M
    The structural characteristics of olivine-type lithium orthophosphate Li(Mg0.5Ni0.5)PO4 synthesized via solid-state reaction have been studied using X-ray diffraction, ion beam technique, scanning electron microscopy, infrared spectroscopy, transmission electron microscopy and energy dispersive X-ray analysis. The parent LiNiPO4 compound can be synthesized in olivine structure without any evidence of secondary phases as impurities. The structural quality of the parent LiNiPO4 in the absence of secondary component phases resulted in the formation of hexagonal closed packed structure. The olivine analogue compound containing mixed M (M = Mg, Ni) cations, Li(Mg0.5Ni0.5)PO4 contained Li3PO4 as a second phase upon synthesis, however a carbothermal reduction method produced a single-phase compound. The redox behaviour of carbon-coated Li(Mg0.5Ni0.5)PO4 cathode in aqueous lithium hydroxide as the electrolyte showed reversible lithium intercalation. © 2020 Springer Nature Switzerland AG.
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    Synthesis and characterization of Li(Co0.5Ni0.5)PO4 cathode for li-ion aqueous battery applications
    (The Electrochemical Society, 2011-03-17) Minakshi, M; Sharma, N; Ralph, D; Appadoo, D; Nallathamby, K
    Olivine-type lithium orthophosphate Li(Co0.5Ni0.5)PO4 was synthesized in a solid state reaction at 800 degrees C in air. Infra-red spectroscopy, x-ray and neutron powder diffraction were used to characterize the as-prepared compound and its electro-oxidized analogue. Rietveld analysis was used to illustrate that the synthesized compound is isostructural with LiNiPO4 and LiCoPO4 with lattice parameters larger than the former and smaller than the latter. The Rietveld-refined Ni:Co ratio was found to be 0.498(4):0.502(4) and no evidence for long-range Ni: Co ordering or mixed Li/Ni/Co cation sites was found. The electro-oxidised electrode showed a mixture of two phases i.e. parent Li(Co0.5Ni0.5)PO4 and lithium extracted Li1-x(Co0.5Ni0.5)PO4 suggesting a delithiation process in aqueous electrolytes. Reversible Li transfer between a Li(Co0.5Ni0.5)PO4 electrode and an aqueous LiOH electrolyte was demonstrated. (C) 2011 The Electrochemical Society. [doi:10.1149/1.3561764]
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    THz/Far-IR astrophysical studies at the Australian synchrotron
    (Institute of Electrical and Electronic Engineers, 2019-09) Appadoo, D; Plathe, R
    THz synchrotron spectroscopy has become an important tool in the identification and quantification of molecular species of astrophysical interest; it is a routinely used technique as it is well established that synchrotron radiation offers a S/N advantage over conventional thermal sources. The brightness advantage is perfectly suited for high-resolution gas-phase spectroscopy, and at the Australian Synchrotron, this advantage is limited to energies lying below 1500 cm-1; however, a flux advantage is maintained for energies below 350 cm-1 which facilitates the study of homogeneous condensed-phase samples. The THz/Far-IR beamline is equipped with a suite of both gas-phase and condensed-phase techniques to enable research on interstellar molecular species, and in this paper, the beamline capabilities available for the study of molecular species of astrophysical interest will be presented. © The authors.