ORCID Profile
0000-0003-4548-1955
Current Organisation
RMIT University
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Materials Engineering | Nanotechnology | Materials Engineering Not Elsewhere Classified | Condensed Matter Physics—Structural Properties | Functional Materials | Nanotechnology | Nanoscale Characterisation | Instruments And Techniques | Other Physical Sciences | Condensed Matter Characterisation Technique Development | Biochemistry and Cell Biology | Condensed Matter Physics | Elemental Semiconductors | Biosensor Technologies | Condensed Matter Imaging | Colloid And Surface Chemistry | Materials Engineering not elsewhere classified | Metals and Alloy Materials | Composite and Hybrid Materials | Solid State Chemistry | Nanomaterials | Interdisciplinary Engineering Not Elsewhere Classified | Plasma Physics; Fusion Plasmas; Electrical Discharges | Composite Materials | Alloy Materials | Physical Chemistry (Incl. Structural) | Surfaces and Structural Properties of Condensed Matter | Synthesis Of Macromolecules | Synchrotrons; Accelerators; Instruments and Techniques | Plant Biology | Macromolecular and materials chemistry | Functional materials | Physical Chemistry Not Elsewhere Classified | Electrical Engineering | Optics And Opto-Electronic Physics | Biomedical Engineering | Optical And Photonic Systems | Plant Cell and Molecular Biology | Other Biological Sciences | Nanobiotechnology | Plasmas And Electrical Discharges | Nanofabrication, Growth and Self Assembly | Structural properties of condensed matter | Ceramics | Microelectronics and Integrated Circuits | Biochemistry and Cell Biology not elsewhere classified | Biological Sciences Not Elsewhere Classified | Animal Cell and Molecular Biology | Medical Parasitology | Condensed Matter Physics—Electronic And Magnetic Properties; | Condensed Matter Physics—Other | Medical Devices | Theory and design of materials | Biomaterials | Electrochemistry | Infectious Agents | Cellular Interactions (incl. Adhesion, Matrix, Cell Wall) | Protein Trafficking | Electronic and Magnetic Properties of Condensed Matter; Superconductivity | Cell Development, Proliferation and Death | Cell Metabolism
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Physical Sciences | Other | Physical sciences | Expanding Knowledge in Technology | Chemical sciences | Expanding Knowledge in the Chemical Sciences | Metals (composites, coatings, bonding, etc.) | Expanding Knowledge in Engineering | Integrated circuits and devices | Biological sciences | Integrated Circuits and Devices | Materials performance and processes | Industrial machinery and equipment | Metals (e.g. Composites, Coatings, Bonding) | Scientific instrumentation | Expanding Knowledge in the Earth Sciences | Expanding Knowledge in the Biological Sciences | Renewable Energy not elsewhere classified | Information processing services | Network switching equipment | Ceramics, Glass and Industrial Mineral Products not elsewhere classified | Appliances and Electrical Machinery and Equipment | Fabricated metal products not elsewhere classified | Health not elsewhere classified | Energy Storage, Distribution and Supply not elsewhere classified | Ceramics | Environmentally Sustainable Plant Production not elsewhere classified | Public Health (excl. Specific Population Health) not elsewhere classified | Manufacturing not elsewhere classified | Ground Transport not elsewhere classified | Basic Metal Products (incl. Smelting, Rolling, Drawing and Extruding) not elsewhere classified | Management of Water Consumption by Plant Production | Solar-Thermal Electric Energy | Solar-Photovoltaic Energy | Basic Iron and Steel Products | Industrial Instruments | Medical Instruments | Basic Aluminium Products | Barley | Wheat | Ceramics, glass and industrial mineral products not elsewhere classified | Control of Pests, Diseases and Exotic Species not elsewhere classified | Energy Storage (excl. Hydrogen) | Metal Castings | Sheet Metal Products | Air Passenger Transport | Manufactured products not elsewhere classified | Coated Metal and Metal-Coated Products | Inorganic industrial chemicals | Energy Transformation not elsewhere classified | Other | Diagnostic methods | Machined products | Diagnostic Methods |
Related Links
Publications
Titanium nitride/vanadium nitride alloy coatings: Mechanical properties and adhesion characteristics
Publisher: Elsevier BV
Date: 03-2006
Refinements in the collection of energy filtered diffraction patterns from disordered materials
Publisher: Elsevier BV
Date: 07-2005
DOI: 10.1016/J.ULTRAMIC.2005.01.002
Abstract: In this paper a method for collecting electron diffraction patterns using a Gatan imaging filter is presented. The method enables high-quality diffraction data to be measured at scattering angles comparable to those that can be obtained using X-ray and neutron diffraction. In addition, the method offers the capability for examining small regions of s le in, for ex le, thin films and nano-structures. Using X-ray, neutron and electron diffraction data collected from the same s le, we demonstrate quantitative agreement between all three. We also present a novel method for obtaining the single scattering contribution to the total diffracted intensity by collecting data at various electron wavelengths. This approach allows pair distribution functions to be determined from electron diffraction in cases where there exists significant multiple scattering.
Mechanical Properties of Plasma Immersion Ion Implanted PEEK for Bioactivation of Medical Devices
Publisher: American Chemical Society (ACS)
Date: 07-10-2015
Abstract: Plasma immersion ion implantation (PIII) is used to modify the surface properties of polyether ether ketone for biomedical applications. Modifications to the mechanical and chemical properties are characterized as a function of ion fluence (treatment time) to determine the suitability of the treated surfaces for biological applications. Young's modulus and elastic recovery were found to increase with respect to treatment time at the surface from 4.4 to 5.2 MPa and from 0.49 to 0.68, respectively. The mechanical properties varied continuously with depth, forming a graded layer where the mechanical properties returned to untreated values deep within the layer. The treated surface layer exhibited cracking under cyclical loads, associated with an increased modulus due to dehydrogenation and cross-linking however, it did not show any sign of delamination, indicating that the modified layer is well integrated with the substrate, a critical factor for bioactive surface coatings. The oxygen concentration remained unchanged at the surface however, in contrast to ion implanted polymers containing only carbon and hydrogen, the oxygen concentration within the treated layer was found to decrease. This effect is attributed to UV exposure and suggests that PIII treatments can modify the surface to far greater depths than previously reported. Protein immobilization on PIII treated surfaces was found to be independent of treatment time, indicating that the surface mechanical properties can be tuned for specific applications without affecting the protein coverage. Our findings on the mechanical properties demonstrate such treatments render PEEK well suited for use in orthopedic implantable devices.
Voltage dependence of cluster size in carbon films using plasma immersion ion implantation
Publisher: Elsevier BV
Date: 05-2003
Carbon evolution during vacuum heat treatment of High Speed Steel
Publisher: Elsevier BV
Date: 02-2016
Investigation of Room Temperature Formation of the Ultra‐Hard Nanocarbons Diamond and Lonsdaleite
Publisher: Wiley
Date: 04-11-2020
Formation of Lead Lanthanum Zirconate Titanate Films by Heat Treatments
Publisher: IEEE
Date: 2005
Lattice guiding for sputter deposition of single domain (Sr0.6Ba0.4)Nb2O6ferroelectric thin films
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C1CE06112G
Effect of intrinsic stress on preferred orientation in AlN thin films
Publisher: AIP Publishing
Date: 30-01-2004
DOI: 10.1063/1.1640462
Abstract: We examine the effect of ion impact energy on the intrinsic stress and microstructure of aluminum nitride thin films deposited using a filtered cathodic arc. The dependence of intrinsic stress on ion impact energy is studied over the range from 0 to 350 V using dc bias and up to several kV for a fraction of the ions using pulse bias. For dc bias, the stress reaches a maximum at 200 V and decreases with further increase in ion bias. The preferred orientation of the crystallites was studied by cross-section transmission electron microscopy and diffraction. We found that there is a preference for the c crystallographic axis to lie in the plane of the film under high intrinsic stress conditions (4 GPa), whereas a c-axis orientation perpendicular to the plane of the film was observed for low intrinsic stress (0.25 GPa). We carried out calculations of the expected distribution of intensity in cross-sectional electron diffraction patterns to predict the effect of rotation freedom of crystallites with the c axis pinned. The calculated patterns agreed well with experiment.
Wannier function analysis for understanding disordered structures generated using car-parrinello molecular dynamics
Publisher: Informa UK Limited
Date: 10-2002
Changes in the electrical resistance of oriented graphitic carbon films induced by atomic hydrogen
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C2TA00198E
Characterisation of titanium nitride thin films prepared using PVD and a plasma immersion ion implantation system
Publisher: Elsevier BV
Date: 05-2002
Graphene Films Prepared Using Energetic Physical Vapor Deposition
Publisher: Springer Science and Business Media LLC
Date: 2017
DOI: 10.1557/ADV.2017.108
Combined nuclear microprobe and TEM study of corrosion pit nucleation by intermetallics in aerospace aluminium alloys
Publisher: Elsevier BV
Date: 04-2005
Nitriding of high speed steel
Publisher: Informa UK Limited
Date: 06-2011
Neuromorphic sensing of biomolecules covalently immobilised on polydimethyl glutarimide
Publisher: Elsevier BV
Date: 10-2023
Multilayered graphene films prepared at moderate temperatures using energetic physical vapour deposition
Publisher: Elsevier BV
Date: 11-2015
A Hydrogen Sensor Based on Graphitic Carbon
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 09-2011
Non-volatile and volatile memory behaviour in oxygenated amorphous carbon electrochemical metallisation devices
Publisher: AIP Publishing
Date: 11-06-2018
DOI: 10.1063/1.5029402
Abstract: The resistive switching behaviour of oxygenated amorphous carbon electrochemical metallisation devices is investigated. The effect of temperature on the microstructure and composition of the oxygenated carbon matrix is also investigated by annealing in situ in a transmission electron microscope. The devices exhibit controllable bipolar non-volatile and bi-directional volatile resistive switching behaviour that is dependent on the resistance state of the device and the polarity of the RESET voltage. The characteristics presented suggest suitability for incorporation into neuromorphic computing and memory storage technologies as memory cells, selector devices, or synaptic emulators.
Analytical electron microscopy of a reaction-bonded Si3N4-based ceramic containing oxide additions
Publisher: Elsevier BV
Date: 1994
Investigation of nitrogen mass transfer within an industrial plasma nitriding system I: The role of surface deposits
Publisher: Elsevier BV
Date: 2010
Ultraviolet detection from graphitic-C/Zn1−xMgxO Schottky devices fabricated at moderate temperatures
Publisher: AIP Publishing
Date: 28-10-2013
DOI: 10.1063/1.4826576
Abstract: Ultraviolet (UV) Schottky detector devices were fabricated on polycrystalline wurtzite Zn1−xMgxO films energetically deposited onto a-plane sapphire at room-temperature (RT) and 200 °C. The unintentionally doped, transparent, n-Zn1−xMgxO films exhibit low surface roughness (& % of film thickness), moderate carrier concentration, and Hall mobility up to 15 cm2 V−1 s−1. The direct bandgaps of the RT and 200 °C films (x = 0.24 and x = 0.20) were 3.57 eV and 3.40 eV. Schottky diodes with graphitic anodes formed on these films exhibited barrier heights up to 0.88 eV and ideality factors as low as 1.97. Spectral response measurements demonstrated UV/visible photo-current ratios up to ∼104.
Structural investigation of xenon-ion-beam-irradiated glassy carbon
Publisher: American Physical Society (APS)
Date: 09-1994
Formation of ordered arrays of gold particles by nanoindentation templating
Publisher: Wiley
Date: 22-10-2013
Reply to Németh and Garvie: Evidence for lonsdaleite in ureilite meteorites
Publisher: Proceedings of the National Academy of Sciences
Date: 08-05-2023
Resistive switching and transport characteristics of an all-carbon memristor
Publisher: Elsevier BV
Date: 09-2018
Observation and characterization of memristive silver filaments in amorphous zinc-tin-oxide
Publisher: Springer Science and Business Media LLC
Date: 13-08-2018
DOI: 10.1557/MRC.2018.156
Device quality ZnO grown using a Filtered Cathodic Vacuum Arc
Publisher: Elsevier BV
Date: 08-2012
Carbon K-shell near-edge structure calculations for graphite using the multiple-scattering approach
Publisher: IOP Publishing
Date: 20-05-1996
Relationship between microstructure and electronic properties of energetically deposited zinc tin oxide
Publisher: IOP Publishing
Date: 19-05-2016
Abstract: Thin films of amorphous n-type zinc tin oxide have been energetically deposited from a filtered cathodic vacuum arc at moderate temperatures. The characteristics of these films span a range suitable for semiconductor devices and transparent conducting oxide interconnects with carrier concentration and mobility dependent on local bonding. X-ray photoelectron spectroscopy (XPS) and electron diffraction have revealed that acceptor-like Sn(II) bonding in the films decreased with increasing growth temperature, resulting in higher n-type carrier concentrations. XPS and in situ Ar plasma treatment showed that downward surface band bending resulted from OH attachment. Persistent photoconductivity was attributed to the photoionization of oxygen vacancies.
Unifying the optical and electrical properties of amorphous carbon: application to hopping photoconductivity and memristance
Publisher: AIP Publishing
Date: 03-12-2020
DOI: 10.1063/5.0024224
Abstract: Amorphous carbon films with an intermediate content of sp3 atoms are finding applications as resistive switches in devices for bio-sensing and for neuromorphic pattern recognition. To understand resistive switching and photoconductivity in amorphous semiconductors dominated by hopping conduction, we present a theory that unifies the optical and electronic properties. The theory considers all of the states to be localized to various extents instead of being extended electronic states. The electronic density of states (eDOS) is modeled with Gaussian functions, symmetric in energy around the Fermi energy. A “hopping mobility” between localized states that is explicitly both energy and temperature dependent is introduced. We describe an ex le application to amorphous carbon films prepared by using high power impulse magnetron sputtering that have a range of sp3 hybridization fractions of the carbon atoms. The electronic bandgaps of the films are observed to correlate with their optical bandgaps. The eDOS is benchmarked against optical property measurements made by ellipsometry. The theory explains the temperature dependence of the resistivity and predicts that the films should show a temperature dependent hopping photoconductivity. Measurements confirm the presence of the photoconductivity and reveal its spectral dependence. A link is made between persistent hopping photoconductivity and resistive switching.
Mechanical and structural modification of CR-39 polymer surface by 50-keV hydrogen and argon ion implantation
Publisher: Elsevier BV
Date: 05-1997
The effect of deposition energy on the microstructure and mechanical properties of high speed steel films prepared using a filtered cathodic vacuum arc
Publisher: Elsevier BV
Date: 08-2010
Plasma immersion ion implantation of poly(tetrafluoroethylene)
Publisher: Elsevier BV
Date: 2004
The microstructure and properties of energetically deposited carbon nitride films
Publisher: Elsevier BV
Date: 05-2014
Abrupt Stress Induced Transformation in Amorphous Carbon Films with a Highly Conductive Transition Phase
Publisher: American Physical Society (APS)
Date: 28-04-2008
Multilayered carbon films for tribological applications
Publisher: Elsevier BV
Date: 02-2003
Bulk Crystalline
4 H
Publisher: American Physical Society (APS)
Date: 25-05-2021
Temperature sensitivity and short-term memory in electroforming-free low power carbon memristors
Publisher: AIP Publishing
Date: 22-04-2019
DOI: 10.1063/1.5094652
Abstract: We report temperature dependent electrical characteristics of two-terminal Ag/a-COx/ta-C/Pt memristors. In these asymmetric devices, defects at the Ag/a-COx interface are passivated by oxygen. This alleviates Fermi level pinning and hence increases the height of the Schottky barrier formed at the interface. Electric-field-induced detrapping of electrons from sp2-related defects in the ta-C causes the observed resistive switching. This occurs entirely in the insulating regime, i.e., with conductance ≪ 2e2/h, enabling ultralow power resistive switching (∼6 nW). Nonlinear temperature dependent ON/OFF ratios and short-term memory characteristics (governed by thermal detrapping kinetics) suggest suitability for temporal neuromorphic computing and sensing applications.
Investigation of nitrogen mass transfer within an industrial plasma nitriding system II: Application of a biased screen
Publisher: Elsevier BV
Date: 2010
External magnetic field guiding in HiPIMS to control sp3 fraction of tetrahedral amorphous carbon films
Publisher: IOP Publishing
Date: 04-11-2020
Abstract: Amorphous carbon films have many applications that require control over their sp 3 fraction to customise the electrical, optical and mechanical properties. Ex les of these applications include coatings for machine parts, biomedical and microelectromechanical devices. In this work, we demonstrate the use of a magnetic field with a high-power impulse magnetron sputtering (HiPIMS) source as a simple, new approach to give control over the sp 3 fraction. We provide evidence that this strategy enhances the deposition rate by focusing the flux, giving films with high tetrahedral bonding at the centre of the deposition field and lower sp 3 fractions further from the centre. Resistive switching appears in films with intermediate sp 3 fractions. The production of thin amorphous carbon films with selected properties without the need for electrical bias opens up applications where insulating substrates are required. For ex le, deposition of sp 3 rich films on polymers for wear resistant coatings as well as fabrication of resistive switching devices for neuromorphic technologies that require tuning of the sp 3 fraction on insulating substrates are now possible.
Soft ferromagnetic materials based on iron/carbon multilayers
Publisher: Elsevier BV
Date: 05-2007
Disintegration ofC 60
Publisher: American Physical Society (APS)
Date: 15-12-1993
Facile, size-controlled deposition of highly dispersed gold nanoparticles on nitrogen carbon nanotubes for hydrogen sensing
Publisher: Elsevier BV
Date: 12-2011
Substrate bias effects on the structural and electronic properties of tetrahedral amorphous carbon
Publisher: American Physical Society (APS)
Date: 15-11-1996
Theoretical and experimental investigation of point defects in cubic boron nitride
Publisher: Springer Science and Business Media LLC
Date: 16-01-2017
DOI: 10.1557/ADV.2017.53
Co-deposition of band-gap tuned Zn1−xMgxO using high impulse power- and dc-magnetron sputtering
Publisher: IOP Publishing
Date: 11-03-2015
Tin oxide artificial synapses for low power temporal information processing
Publisher: IOP Publishing
Date: 08-05-2019
Abstract: Lateral memristors configured with inert Pt contacts and mixed phase tin oxide layers have exhibited immediate, forming-free, low-power bidirectional resistance switching. Activity dependent conductance and relaxation in the low resistance state resembled short term potentiation in biological synapses. After scanning probe microscopy, x-ray photoelectron spectroscopy and electrical measurements, the device characteristics were attributed to Joule heating induced decomposition of the minority SnO phase and formation of a SnO
Controlled surface modification of boron nitride nanotubes
Publisher: IOP Publishing
Date: 20-04-2011
Experimental and theoretical characterization of structure in thin disordered films
Publisher: International Union of Crystallography (IUCr)
Date: 03-1999
DOI: 10.1107/S0108767398008769
Abstract: The electron microscope provides an ideal environment for the structural analysis of small volumes of amorphous and polycrystalline materials by enabling the collection of scattering information as a function of energy loss and momentum transfer. The scattered intensity at zero energy loss can be readily processed to a reduced density function, providing information on nearest-neighbour distances and bond angles. A method for collecting and processing the scattered intensity, which allows for the collection of an energy-loss spectrum for a range of momentum transfers, is discussed. A detailed structural determination from a reduced density function alone is difficult and it is shown that a more detailed structural model can be obtained by combining the experimental reduced density function with model structures obtained from molecular dynamics based on first-principles quantum mechanics. This method is applied to tetrahedral amorphous carbon, as an ex le of a monatomic network, and to aluminium nitride, as a prototype for a binary amorphous alloy.
The encapsulation of Ni in graphitic layers using C60 as a precursor
Publisher: Elsevier BV
Date: 10-2001
Highly dispersed gold nanoparticles on nitrogen doped carbon nanotubes for hydrogen sensing
Publisher: IEEE
Date: 11-2010
Ion implantation in tetrahedral amorphous carbon
Publisher: American Physical Society (APS)
Date: 07-1995
Light-gated amorphous carbon memristors with indium-free transparent electrodes
Publisher: Elsevier BV
Date: 11-2019
High-temperature formation of concentric fullerene-like structures within foam-like carbon: Experiment and molecular dynamics simulation
Publisher: American Physical Society (APS)
Date: 15-06-2007
Oriented graphitic carbon films for hydrogen gas sensors
Publisher: IEEE
Date: 11-2010
Microstructural investigation supporting an abrupt stress induced transformation in amorphous carbon films
Publisher: AIP Publishing
Date: 15-04-2009
DOI: 10.1063/1.3075867
Abstract: The intrinsic stress of carbon thin films deposited by filtered cathodic arc was investigated as a function of ion energy and Ar background gas pressure. The microstructure of the films was analyzed using transmission electron microscopy, electron energy loss spectroscopy, and Raman spectroscopy. The stress at given substrate bias was reduced by the presence of an Ar background gas and by the presence of a Cu underlayer deposited onto the substrate prior to deposition. Auger electron spectroscopy depth profiles showed no evidence of Ar incorporation into the films. A sharp transition from a sp2 to sp3 rich phase was found to occur at a stress of 6.5±1.5 GPa, independent of the deposition conditions. The structural transition at this value of stress is consistent with available data taken from the literature and also with the expected value of biaxial stress at the phase boundary between graphite and diamond at room temperature. The microstructure of films with stress in the transition region near 6.5 GPa was consistent with a mixture of sp2 and sp3 rich structures.
Mechanism for the Amorphisation of Diamond
Publisher: Wiley
Date: 15-03-2012
Abstract: The breakdown of the diamond lattice is explored by ion implantation and molecular dynamics simulations. We show that lattice breakdown is strain-driven, rather than damage-driven, and that the lattice persists until 16% of the atoms have been removed from their lattice sites. The figure shows the transition between amorphous carbon and diamond, with the interfaces highlighted with dashed lines.
Synaptic plasticity and oscillation at zinc tin oxide/silver oxide interfaces
Publisher: AIP Publishing
Date: 07-02-2017
DOI: 10.1063/1.4975412
Abstract: Short-term plasticity, long-term potentiation, and pulse interval dependent plasticity learning/memory functions have been observed in junctions between amorphous zinc-tin-oxide and silver-oxide. The same junctions exhibited current-controlled negative differential resistance and when connected in an appropriate circuit, they behaved as relaxation oscillators. These oscillators produced voltage pulses suitable for device programming. Transmission electron microscopy, energy dispersive X-ray spectroscopy, and electrical measurements suggest that the characteristics of these junctions arise from Ag+/O− electromigration across a highly resistive interface layer. With memory/learning functions and programming spikes provided in a single device structure, arrays of similar devices could be used to form transistor-free neuromorphic circuits.
Influence of bias and in situ cleaning on through cage (TC) or active screen plasma nitrided (ASPN) steels
Publisher: Informa UK Limited
Date: 08-2006
The Near Edge Structure of Hexagonal Boron Nitride
Publisher: Oxford University Press (OUP)
Date: 23-04-2014
DOI: 10.1017/S1431927614000737
Abstract: Hexagonal boron nitride (hBN) is a promising material for a range of applications including deep-ultraviolet light emission. Despite extensive experimental studies, some fundamental aspects of hBN remain unknown, such as the type of stacking faults likely to be present and their influence on electronic properties. In this paper, different stacking configurations of hBN are investigated using CASTEP, a pseudopotential density functional theory code. AB-b stacking faults, in which B atoms are positioned directly on top of one another while N atoms are located above the center of BN hexagons, are shown to be likely in conventional AB stacked hBN. Bandstructure calculations predict a single direct bandgap structure that may be responsible for the discrepancies in bandgap type observed experimentally. Calculations of the near edge structure showed that different stackings of hBN are distinguishable using measurements of core-loss edges in X-ray absorption and electron energy loss spectroscopy. AB stacking was found to best reproduce features in the experimental B and N K-edges. The calculations also show that splitting of the 1 s to π * peak in the B K-edge, recently observed experimentally, may be accounted for by the presence of AB-b stacking faults.
Synthesis of nanostructured tungsten oxide thin films: A simple, controllable, inexpensive, aqueous sol-gel method
Publisher: American Chemical Society (ACS)
Date: 29-10-2010
DOI: 10.1021/CG9010295
An ab initio study of structural properties and single vacancy defects in Wurtzite AlN
Publisher: AIP Publishing
Date: 03-2004
DOI: 10.1063/1.1645790
Abstract: The cell parameters, bulk moduli and electronic densities-of-states (DOS) of pure and vacancy defect AlN were computed using generalized-gradient approximation (GGA) and hybrid functional (B3LYP) computational methods within both plane wave-pseudopotential and localized Gaussian basis set approaches. All of the methods studied yielded cell parameters and bulk moduli in reasonable agreement with experiment. The B3LYP functional was also found to predict an optical band gap in excellent agreement with experiment. These methods were subsequently applied to the calculation of the geometry, defect state positions and formation energies of the cation (VAl) and anion (VN) single vacancy defects. For the VAl defect, the plane wave-pseudopotential predicted a significant retraction of the neighboring N away from the vacancy, while for the VN defect, only slight relaxations of the surrounding Al atoms towards the vacancy were predicted. For the computed DOS of both vacancy defects, the GGA methods yielded similar features and defect level positions relative to the valence band maximum, while the B3LYP method predicted higher separations between the defect levels and the valence and conduction bands, leading to higher energy occupied defect levels.
The effect of annealing and implantation temperature on the structure of C ion-beam-irradiated glassy carbon
Publisher: AIP Publishing
Date: 09-1995
DOI: 10.1063/1.360054
Abstract: Raman spectroscopy has been used to investigate the effects of dynamic and postimplantation annealing on glassy carbon implanted with 50 keV C ions to a dose of 5×1016 ions/cm2. The postimplantation annealing of damage in the ion-beam modified material was found to occur in two stages as a function of postimplantation annealing temperature Ta. These occur for 500& Ta& K and Ta≳1300 K and correspond to the thermal energy required to activate C interstitials and vacancies, respectively. Once mobile these defects diffuse through the implanted layer, reducing bond angle disorder which leads to an increase in graphitic order as interstitial-vacancy recombination occurs. The effects of the ion-beam irradiation on the final structure of glassy carbon were found to be a strong function of the temperature of the s le during the irradiation, Ti. This dependence is interpreted in terms of dynamic annealing and radiation-enhanced diffusion. Three temperature regimes were found to be important. For Ti& K defect motion during irradiation is suppressed. For 300& Ti& K, the mobility of C interstitials during irradiation results in dynamic annealing which prevents amorphization, with the result that the ion irradiation creates a highly disordered, but essentially graphitically bonded carbon. For Ti≳600 K, vacancy mobilities are sufficiently high such that most ion-beam-induced defects are dynamically annealed and, for Ti≳800 K the unimplanted glassy carbon microstructure is retained following the ion-beam irradiation. Finally, activation energies for interstitial and vacancy mobilities were determined and found to compare favorably with those found in other forms of carbon.
Co-operative corrosion phenomena
Publisher: Elsevier BV
Date: 03-2010
Structural and chemical bonding investigation of tungsten implanted glassy carbon
Publisher: Elsevier BV
Date: 1993
Neutron diffraction discriminates between models for the nanoarchitecture of graphene sheets in glassy carbon
Publisher: Elsevier BV
Date: 02-2021
Ion-beam modification of fullerene
Publisher: American Physical Society (APS)
Date: 07-1995
Fabrication of Nanoscale Multilayer Device by Filtered Cathodic Vacuum Arc for Optical Application
Publisher: IEEE
Date: 2006
Ion-beam induced compaction in glassy carbon
Publisher: AIP Publishing
Date: 07-1993
DOI: 10.1063/1.354145
Abstract: Cross-sectional transmission electron microscopy has been used to investigate the implanted layer in glassy carbon irradiated with 50 keV C ions to a dose of 5×1016 ions/cm2. It was found that in addition to the formation of an amorphous surface layer approximately 100 nm deep, the ion-beam modified layer was compacted from the unirradiated density of 1.5 to 2.4±0.2 g/cm3. Ion implantation was also found to increase the refractive index of glassy carbon from 1.8±0.1 to 2.4±0.1 which is also consistent with the proposition that an increase in the density of the implanted layer has occurred. The formation of a dense, amorphous carbon surface layer could explain the observed increase in wear resistance of glassy carbon following ion implantation.
The stress and microstructure of a‐C multilayers deposited using a filtered cathodic vacuum arc and periodic substrate bias
Publisher: Wiley
Date: 10-2009
Electroformed, Self‐Connected Tin Oxide Nanoparticle Networks for Electronic Reservoir Computing
Publisher: Wiley
Date: 20-05-2020
The effect of annealing on the structure of cathodic arc deposited amorphous carbon nitride films
Publisher: Elsevier BV
Date: 12-1996
Plasma-based ion implantation utilising a cathodic arc plasma
Publisher: Elsevier BV
Date: 07-2002
Mechanisms for the behavior of carbon films during annealing
Publisher: American Physical Society (APS)
Date: 08-2004
Fullerenes as precursors for nanocapsule formation
Publisher: Informa UK Limited
Date: 2000
The near edge structure of cubic boron nitride
Publisher: Elsevier BV
Date: 2012
DOI: 10.1016/J.MICRON.2011.07.004
Abstract: We compare the near edge structure (NES) of cubic boron nitride (cBN) measured using both electron energy loss spectroscopy (EELS) and X-ray absorption spectroscopy (XAS) with that calculated using three commonly used theoretical approaches. The boron and nitrogen K-edges collected using EELS and XAS from cBN powder were found to be nearly identical. These experimental edges were compared to calculations obtained using an all-electron density functional theory code (WIEN2k), a pseudopotential density functional theory code (CASTEP) and a multiple scattering code (FEFF). All three codes were found to reproduce the major features in the NES for both ionisation edges when a core-hole was included in the calculations. A partial core hole (1/2 of a 1s electron) was found to be essential for correctly reproducing features near the edge threshold in the nitrogen K-edge and to correctly obtain the positions of all main peaks. CASTEP and WIEN2k were found to give almost identical results. These codes were also found to produce NES which most closely matched experiment based on χ² calculations used to qualitatively compare theory and experiment. This work demonstrated that a combined experimental and theoretical approach to the study of NES is a powerful way of investigating bonding and electronic structure in boron nitride and related materials.
Ohmic and rectifying contacts to n-SiC formed by energetic deposition of carbon
Publisher: Springer Science and Business Media LLC
Date: 2014
DOI: 10.1557/OPL.2014.570
Abstract: Energetically-deposited carbon contacts to n-type 6H-SiC have exhibited either insulating, rectifying or ohmic electrical characteristics depending on the average energy of the depositing flux and the substrate temperature. Deposition at room temperature and at a low-medium average energy ( 500 eV) has resulted in carbon with a low graphitic content and insulating electrical contacts. With higher average energy and at a moderately elevated temperature (∼100 °C), the higher graphitic content contacts were rectifying with an ideality factor, η, of ∼1.8 and barrier height of ∼0.88 eV. Oriented graphitic carbon deposited at 200 °C with biases exceeding 300 V formed ohmic contacts.
Electrical conductivity as a measure of the continuity of titanium and vanadium thin films
Publisher: Elsevier BV
Date: 03-2005
Nanostructured SnO2films prepared from evaporated Sn and their application as gas sensors
Publisher: IOP Publishing
Date: 20-02-2008
DOI: 10.1088/0957-4484/19/12/125504
Abstract: This paper describes the morphology, stoichiometry, microstructure and gas sensing properties of nanoclustered SnO(x) thin films prepared by Sn evaporation followed by a rheotaxial growth and thermal oxidation process. Electron microscopy was used to investigate, in detail, the evolution of the films as the oxidation temperature was increased. The results showed that the contact angle, perpendicular height, volume and microstructure of the clusters all changed significantly as a result of the thermal oxidation processes. Electron diffraction and x-ray photoelectron spectroscopy measurements revealed that after oxidation at a temperature of 600 °C, the Sn clusters were fully transformed into porous three-dimensional polycrystalline SnO(2) clusters. On the basis of these results, a prototype SnO(2) sensor was fabricated and sensing measurements were performed with H(2) and NO(2) gases. At operating temperatures of 150-200 °C the film produced measurable responses to concentrations of H(2) as low as 600 ppm and NO(2) as low as 500 ppb.
Graphitization of Glassy Carbon after Compression at Room Temperature
Publisher: American Physical Society (APS)
Date: 23-05-2018
Antireflective trilayer films fabricated using a filtered cathodic vacuum arc
Publisher: SPIE
Date: 28-08-2008
DOI: 10.1117/12.795634
Correlation between stress and hardness in pulsed cathodic arc deposited titanium/vanadium nitride alloys
Publisher: IOP Publishing
Date: 30-10-2004
Oriented graphene films for use as high-performance thermal and electrical interconnects
Publisher: SPIE
Date: 26-12-2008
DOI: 10.1117/12.815405
Rectifying electrical contacts to n-type 6H–SiC formed from energetically deposited carbon
Publisher: Elsevier BV
Date: 06-2016
The interface structure of high performance ZnO Schottky diodes
Publisher: Elsevier BV
Date: 08-2012
A combinatorial comparison of DC and high power impulse magnetron sputtered Cr2AlC
Publisher: Elsevier BV
Date: 11-2014
Smoothening of wrinkles in CVD-grown hexagonal boron nitride films
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8NR03984D
Abstract: Hexagonal boron nitride (h-BN) is an ideal substrate for two-dimensional (2D) materials because of its unique electrically insulating nature, atomic smoothness and low density of dangling bonds.
Physical and Spectroscopic Studies of Polypyrrole Films Containing Transition-Metal EDTA Chelates
Publisher: American Chemical Society (ACS)
Date: 05-1994
DOI: 10.1021/CM00041A022
Enhancing the hardness of Al/W nanostructured coatings
Publisher: IOP Publishing
Date: 16-12-2009
DOI: 10.1088/0953-8984/21/5/055003
Abstract: Two-component multilayer thin films frequently show hardness enhancements at specific repeat periods above that of the constituent layers. This study of hardness enhancements in W/Al nanostructured coatings provides strong new evidence that hardness enhancements in this system arise not only from the presence of a layered structure, but also from the presence of defects introduced by changing the deposition conditions. S les with well defined layers of W and Al were produced by sputtering to cover a wide range of periods from 10 to 200 nm. No evidence of enhanced hardness in these films was found by nanoindentation. On the other hand, s les deposited from cathodic arc sources showed strong hardness enhancement above that of pure W. However, the s les of highest hardness did not contain Al layers for much of their thickness. The hardening mechanism therefore could not be attributed to the presence of a multilayer structure. Examination of the microstructure showed that the interruptions to the W deposition caused by operation of the Al source introduced defects which acted as pinning sites for dislocations. The nanoindentation hardness data were well described using a modified Hall-Petch relation.
The effect of carbon and nitrogen implantation on the abrasion resistance of type IIa (110) diamond
Publisher: Elsevier BV
Date: 1993
Controlled morphogenesis and self-assembly of bismutite nanocrystals into three-dimensional nanostructures and their applications
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3TA14587E
Abstract: We report the morphogenesis and self-assembly of bismutite nanocrystals with fully tunable morphologies from square plates, octagonal sheets, and round disks into three-dimensional hierarchical nanostructures.
Self-organized carbon nanotubes grown at the grain boundary of iron-nitride
Publisher: Elsevier BV
Date: 2005
The composition, structure and properties of four different glassy carbons
Publisher: Elsevier BV
Date: 10-2019
Characterization and device applications of ZnO films deposited by high power impulse magnetron sputtering (HiPIMS)
Publisher: IOP Publishing
Date: 03-04-2013
Mechanisms for the behaviour of amorphous carbon films during annealing
Publisher: Oxford University Press (OUP)
Date: 08-2004
DOI: 10.1017/S1431927604886100
Abstract: Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.
Modification of the mechanical and optical properties of a polycarbonate by 50 keV Ar+and H+ion implantation
Publisher: AIP Publishing
Date: 15-03-1998
DOI: 10.1063/1.367108
Abstract: The effects of 50 keV H+ and Ar+ ions on the mechanical properties and ultraviolet-visible absorption of the polymer CR39 were investigated. It was found that the H+ implantation produced a yellow–brown material with optical properties similar to amorphous hydrogenated carbon, whereas Ar+ implantation produced a material with optical properties more like evaporated amorphous carbon. The mechanical properties of the implanted material were measured using a nanoindentation technique and increases in both the elastic modulus and hardness (maximum sustainable contact pressure) were observed following irradiation with both ion species. Compared to Ar+ implantation, H+ implantation of CR39 was found to produce a more transparent material at an equivalent maximum sustainable contact pressure and therefore H+ ions were found to be more desirable than Ar+ ions for the treatment of CR39 optical components.
Ion beam modification of tetrahedral amorphous carbon: the effect of irradiation temperature
Publisher: Elsevier BV
Date: 10-1997
Pulsed external magnetic fields increase the deposition rate in reactive HiPIMS while preserving stoichiometry: An application to amorphous HfO2
Publisher: AIP Publishing
Date: 08-09-2016
DOI: 10.1063/1.4961730
Abstract: We compare the use of externally applied pulsed and steady magnetic fields for the enhancement of deposition rate in reactive High Power Impulse Magnetron Sputtering (HiPIMS), using the deposition of amorphous hafnium oxide (a-HfO2) on Si as an ex le. The external magnetic fields were applied by a solenoidal coil, placed above the magnetron target. In the case of a steady magnetic field, a higher voltage was required to initiate the HiPIMS discharge, a longer delay time was observed for current onset, and the films became substoichiometric. For the pulsed magnetic field, film stoichiometry was maintained under all applied external magnetic field strengths. Varying the duration and delay times of the magnetic field after the application of HiPIMS voltage pulse revealed that the afterglow of the plasma between HiPIMS pulses was actively quenched by the presence of the magnetic field. Therefore, the optimum operation with the highest plasma density was obtained by applying the external magnetic field only when the plasma was established and removing it at the end of the HiPIMS pulse. A model to explain the findings is presented in which the target poisoning by oxide formation is determined by the conditions in the afterglow. We describe an approach to achieve maximum deposition rate while maintaining film stoichiometry and high film quality. Amorphous HfO2 films with leakage current through the film of less than 5 × 10−5 A/cm2 at 0.1 MV/cm were obtained at the maximum deposition rate. The refractive index, at a wavelength of 500 nm, of the film prepared with pulsed magnetic field was 2.05 with a very low extinction coefficient of 8 × 10−5.
Energetically deposited nano-composite films of high speed steel and titanium nitride
Publisher: Elsevier BV
Date: 11-2014
The microstructure and mechanical properties of TiNNi nanocomposite thin films
Publisher: Elsevier BV
Date: 11-2013
Styrene epoxidation over gold supported on different transition metal oxides prepared by homogeneous deposition–precipitation
Publisher: Elsevier BV
Date: 11-2004
Changes in oriented graphitic carbon properties upon exposure to atomic hydrogen
Publisher: Elsevier BV
Date: 2020
Reverse Monte Carlo analysis of the structure of glassy carbon using electron-microscopy data
Publisher: American Physical Society (APS)
Date: 06-1998
Conducting carbon films with covalent binding sites for biomolecule attachment
Publisher: AIP Publishing
Date: 15-02-2019
DOI: 10.1063/1.5066565
Abstract: We report an electrically conductive carbon film with controllable hydrophilic properties that offers a covalent binding surface containing radicals for biomolecule attachment without using chemical linkers. Films were deposited from an acetylene-containing plasma using plasma immersion ion implantation during growth and subsequently annealed under vacuum. Electrical conductivity, spin density, contact angle, surface energy, surface composition, and covalent binding capability were studied as a function of annealing temperature, revealing three distinct regions. In the first region, surface energy is dominated by polar groups. In the second region, the polar groups are expelled, creating unpaired electrons that dominate the polar component of the surface energy. In the third region, the electrical conductivity rises and the polar component of surface energy falls as the unpaired electrons recombine, leading to an optimum combination of surface energy, spin density, and electrical conductivity for biological applications. It is proposed that persistent radicals are responsible for both high wettability and covalent binding properties. Covalently attached enzyme molecules on the C film can resist stringent washing with detergents. The C films offer the functions of conducting polymers, but with the added features of controllable wettability and a covalent binding capability.
Nanoporous titanium oxide synthesized from anodized Filtered Cathodic Vacuum Arc Ti thin films
Publisher: Elsevier BV
Date: 12-2009
Characterization of non-Cr-based deoxidizers on Al alloy 7475-T7651
Publisher: Wiley
Date: 2004
DOI: 10.1002/SIA.1938
Applications of tetrahedral amorphous carbon in limited volatility memory and in field programmable gate arrays
Publisher: Elsevier BV
Date: 02-2001
Microstructure of an industrial char by diffraction techniques and Reverse Monte Carlo modelling
Publisher: Elsevier BV
Date: 2004
Fullerene blacks and cathode deposits derived from plasma arcing of graphite with naphthalene
Publisher: Elsevier BV
Date: 2000
Sequential Lonsdaleite to Diamond Formation in Ureilite Meteorites via In Situ Chemical Fluid/Vapor Deposition
Publisher: Proceedings of the National Academy of Sciences
Date: 12-09-2022
Abstract: Ureilite meteorites are arguably our only large suite of s les from the mantle of a dwarf planet and typically contain greater abundances of diamond than any known rock. Some also contain lonsdaleite, which may be harder than diamond. Here, we use electron microscopy to map the relative distribution of coexisting lonsdaleite, diamond, and graphite in ureilites. These maps show that lonsdaleite tends to occur as polycrystalline grains, sometimes with distinctive fold morphologies, partially replaced by diamond + graphite in rims and cross-cutting veins. These observations provide strong evidence for how the carbon phases formed in ureilites, which, despite much conjecture and seemingly conflicting observations, has not been resolved. We suggest that lonsdaleite formed by pseudomorphic replacement of primary graphite shapes, facilitated by a supercritical C-H-O-S fluid during rapid decompression and cooling. Diamond + graphite formed after lonsdaleite via ongoing reaction with C-H-O-S gas. This graphite lonsdaleite diamond + graphite formation process is akin to industrial chemical vapor deposition but operates at higher pressure (∼1–100 bar) and provides a pathway toward manufacture of shaped lonsdaleite for industrial application. It also provides a unique model for ureilites that can reconcile all conflicting observations relating to diamond formation.
Self-assembled V2O5 interconnected microspheres produced in a fish-water electrolyte medium as a high-performance lithium-ion-battery cathode
Publisher: Springer Science and Business Media LLC
Date: 16-09-2015
Energetic deposition of carbon clusters with preferred orientation using a new mixed mode cathodic arc – Sputtering process
Publisher: Elsevier BV
Date: 03-2010
The origin of preferred orientation during carbon film growth
Publisher: IOP Publishing
Date: 22-04-2009
DOI: 10.1088/0953-8984/21/22/225003
Abstract: Carbon films were prepared using a filtered cathodic vacuum arc deposition system operated with a substrate bias varying linearly with time during growth. Ion energies were in the range between 95 and 620 eV. Alternating dark, high density (sp(3) rich) bands and light, low density (sp(2) rich) bands were observed using cross-sectional transmission electron microscopy, corresponding to abrupt transitions between materials with densities of approximately 3.1 and 2.6 g cm(-3). No intermediate densities were observed in the s les. The low density bands show strong preferred orientation with graphitic sheets aligned normal to the film. After annealing, the low density bands became more oriented and the thinner high density layers were converted to low density material. In molecular dynamics modelling of film growth, temperature activated structural rearrangements occurring over long timescales ([Formula: see text] ps) caused the transition from sp(3) rich to oriented sp(2) rich structure. Once this oriented growth was initiated, the sputtering yield decreased and channelling was observed. However, we conclude that sputtering and channelling events, while they occur, are not the cause of the transition to the oriented structure.
Modeling of structure and porosity in amorphous silicon systems using Monte Carlo methods
Publisher: AIP Publishing
Date: 05-06-2007
DOI: 10.1063/1.2743029
Abstract: Porous solids are very important from a scientific point of view as they provide a medium in which to study the behavior of confined fluids. Although some porous solids have a well defined pore geometry such as zeolites, many porous solids lack crystalline order and are usually described as amorphous. The description of the pore geometry in such structures is very difficult. The authors develop a modeling approach using a Monte Carlo algorithm to simulate porosity within amorphous systems based on constraints for the internal volume and surface area. To illustrate this approach, a model of microporous amorphous silicon is presented. Structural aspects of the porous model are then compared against hybrid reverse Monte Carlo simulations of nonporous amorphous silicon and published results from the literature. It is found that coordination defects are predominately located at the pore surface walls.
Monte Carlo based modeling of carbon nanostructured surfaces
Publisher: American Physical Society (APS)
Date: 13-09-2005
Toughening of a trifunctional epoxy system Part III. Kinetic and morphological study of the thermoplastic modified cure process
Publisher: Elsevier BV
Date: 04-2000
Metal ion implantation using a filtered cathodic vacuum arc
Publisher: AIP Publishing
Date: 05-2000
DOI: 10.1063/1.373052
Abstract: When plasma immersion ion implantation is performed in the condensable plasma stream produced by a cathodic vacuum arc, deposition as well as implantation usually occurs. In this article we describe a method of achieving pure implantation by orienting the substrate so that it is shadowed from the plasma beam. Implantation depth profiles measured in glassy carbon and CR39 polymer using Rutherford backscattering are compared to illustrate the effectiveness of the technique for conducting and insulating substrates. Charging of the insulating substrate was found to cause a reduction in implantation depth compared to a conducting substrate. The depth profiles in glassy carbon were comparable to those achieved by conventional extracted ion beam implantation. Implantation of magnesium into hydroxyapatite and alumina was carried out to improve the bone cell adhesion onto these materials for prosthetic applications.
Energetic deposition, measurement and simulation of graphitic contacts to 6H-SiC
Publisher: Elsevier BV
Date: 04-2017
Graphitic Schottky Contacts to Si formed by Energetic Deposition
Publisher: Springer Science and Business Media LLC
Date: 2015
DOI: 10.1557/OPL.2015.824
Abstract: Carbon films deposited by filtered cathodic vacuum arc have been used to form high quality Schottky diodes on p-Si. Energetic deposition with an applied substrate bias of -1 kV and with a substrate temperature of 100 °C has produced carbon diodes with rectification ratios of ∼ 3 × 10 6 , saturation currents of ∼0.02 nA and ideality factors close to unity (n = 1.05). Simulations were used to estimate the effective work function and the thickness of an interfacial mixed (C/SiO 2 ) layer from the current/voltage characteristics of the diodes.
Effect of crystallographic orientation on the anodic formation of nanoscale pores/tubes in TiO2 films
Publisher: Elsevier BV
Date: 10-2009
Mixed-mode high-power impulse magnetron sputter deposition of tetrahedral amorphous carbon with pulse-length control of ionization
Publisher: AIP Publishing
Date: 21-04-2016
DOI: 10.1063/1.4946841
Abstract: High-power impulse magnetron sputtering (HiPIMS) is used to deposit amorphous carbon thin films with sp3 fractions of 13% to 82%. Increasing the pulse length results in a transition from conventional HiPIMS deposition to a “mixed-mode” in which an arc triggers on the target surface, resulting in a large flux of carbon ions. The films are characterized using X-ray photoelectron spectroscopy, Raman spectroscopy, ellipsometry, nanoindentation, elastic recoil detection analysis, and measurements of stress and contact angle. All properties vary in a consistent manner, showing a high tetrahedral character only for long pulses, demonstrating that mixed-mode deposition is the source of the high carbon ion flux. Varying the substrate bias reveals an “energy window” effect, where the sp3 fraction of the films is greatest for a substrate bias around −100 V and decreases for higher or lower bias values. In the absence of bias, the films' properties show little dependence on the pulse length, showing that energetic ions are the origin of the highly tetrahedral character.
Corrosion of AA2024-T3 Part I: Localised corrosion of isolated IM particles
Publisher: Elsevier BV
Date: 2011
Synthesis and in-situ ellipsometric monitoring of Ti/C nanostructured multilayers using a high-current, dual source pulsed cathodic arc
Publisher: Elsevier BV
Date: 06-2005
Structural characterisation of energetically deposited Zn 1−x Mg x O films
Publisher: Elsevier BV
Date: 02-2015
The microstructure and stability of Al/AlN multilayered films
Publisher: AIP Publishing
Date: 07-2006
DOI: 10.1063/1.2204816
Abstract: Al ∕ Al N multilayers with bilayer thicknesses ranging from 10to50nm were fabricated using a filtered cathodic arc deposition system. The effects on the microstructure of using two different deposition rates and applying an 8kV pulsed voltage (plasma immersion ion implantation or PIII) to the substrate were explored. The microstructure was found to undergo a transition in which the Al transformed from layers to an aggregated phase under some conditions. This behavior is explained by a model in which the aggregation process is limited by diffusion. High deposition rates and the application of PIII were both found to encourage the transition by increasing diffusion. The model defines a phase diagram which predicts whether a multilayer or an aggregated structure will occur. A maximum in intrinsic stress was found to occur when the average feature size was 15nm for both layers and aggregates.
In situ analysis of the structural transformation of glassy carbon under compression at room temperature
Publisher: American Physical Society (APS)
Date: 30-01-2019
Fabrication, Structural Characterization and Testing of a Nanostructured Tin Oxide Gas Sensor
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 05-2009
Optical properties and oxidation of carbonized and cross-linked structures formed in polycarbonate by plasma immersion ion implantation
Publisher: Elsevier BV
Date: 06-2014
A crystallographic study of dislocation cell arrangement in aluminium deformed at an elevated temperature
Publisher: Elsevier BV
Date: 05-1995
Multilayer structure, stress reduction and annealing of carbon film.
Publisher: Springer Science and Business Media LLC
Date: 2003
Abstract: Carbon films deposited by filtered cathodic arc show a high compressive stress which limits their thickness because of delamination. We study three methods of relieving the stress in these films. We first determine the dependence of the stress on DC bias up to bias voltages of 1200V and show that the formula of Davis provides a good fit to the data including the stress maximum in the region of 150–200V and the progressive decrease in stress at higher voltages. In the second method, plasma immersion ion implantation (PIII) was used to create multilayer of alternating high density, high stress (PIII on) films and lower density, low stress (PIII off) films. This method enabled thicker structures to be produced. In the third method we made multilayers using amorphous silicon and carbon layers. Annealing of these layers showed that the stress could be reduced to very low values because of the ability of the silicon layers to absorb compressive stress by contracting after the annealing step. The microstructural effects of PIII were studied by transmission and scanning electron microscopy.
Dark field microscopy for diffraction analysis of non crystalline materials
Publisher: Oxford University Press (OUP)
Date: 08-2004
DOI: 10.1017/S1431927604886379
Abstract: Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.
Relation between microstructure and stress in titanium nitride films grown by plasma immersion ion implantation
Publisher: AIP Publishing
Date: 21-03-2003
DOI: 10.1063/1.1558995
Abstract: Polycrystalline and microcrystalline materials grown as thin films often exhibit a preferred crystallographic orientation. The mechanism by which this preferred orientation develops has been the subject of some debate. In this article we present the results of electron microscopy and diffraction experiments examining preferred orientation in titanium–nitride (TiN) films deposited by physical vapor deposition with bombardment energies up to 18 keV using plasma immersion ion implantation. We show that as the bombardment energy increases the intrinsic stress is reduced. For ex le, at 3 kV more than a 50% reduction in stress is achieved. The results are consistent with a model in which the preferred orientation is the result of minimizing the energy, which includes both surface energy and bulk strain energy terms.
Nanocrystalline hexagonal diamond formed from glassy carbon
Publisher: Springer Science and Business Media LLC
Date: 29-11-2016
DOI: 10.1038/SREP37232
Abstract: Carbon exhibits a large number of allotropes and its phase behaviour is still subject to significant uncertainty and intensive research. The hexagonal form of diamond, also known as lonsdaleite, was discovered in the Canyon Diablo meteorite where its formation was attributed to the extreme conditions experienced during the impact. However, it has recently been claimed that lonsdaleite does not exist as a well-defined material but is instead defective cubic diamond formed under high pressure and high temperature conditions. Here we report the synthesis of almost pure lonsdaleite in a diamond anvil cell at 100 GPa and 400 °C. The nanocrystalline material was recovered at ambient and analysed using diffraction and high resolution electron microscopy. We propose that the transformation is the result of intense radial plastic flow under compression in the diamond anvil cell, which lowers the energy barrier by “locking in” favourable stackings of graphene sheets. This strain induced transformation of the graphitic planes of the precursor to hexagonal diamond is supported by first principles calculations of transformation pathways and explains why the new phase is found in an annular region. Our findings establish that high purity lonsdaleite is readily formed under strain and hence does not require meteoritic impacts.
The structure of disordered carbon solids studied using a hybrid reverse Monte Carlo algorithm
Publisher: IOP Publishing
Date: 15-04-2005
Nanoscale momentum-resolved vibrational spectroscopy
Publisher: American Association for the Advancement of Science (AAAS)
Date: 06-2018
Abstract: A widely applicable method for accessing phonon dispersions of materials at high spatial resolution is demonstrated.
Engineering titanium and aluminum oxide composites using atomic layer deposition
Publisher: AIP Publishing
Date: 15-12-2011
DOI: 10.1063/1.3667134
Abstract: Mixed metal oxides provide a convenient means to produce coatings with tailored physical properties. We investigate the possibility of synthesizing novel coatings of mixed titanium and aluminum oxide using atomic layer deposition (ALD). Results show that ALD films were prepared with compositions ranging between Al2O3 and TiO2 having refractive indices between 1.6 and 2.4 (at λ = 550 nm) at low temperature. The microstructure and bonding environment within the films was investigated using electron microscopy and x-ray absorption spectroscopy. The films were amorphous, and the Ti and Al atoms were mixed at the atomic scale. The electrical breakdown characteristics of the films were measured and showed that films with intermediate compositions had poor leakage current properties, believed to be caused by the presence of distorted bonding configurations. This study shows that ALD can be used to deposit high quality thin films with tailored optical properties, particularly suitable for applications in which complex topographies are required.
A Pt/oriented-C hydrogen gas sensor
Publisher: IEEE
Date: 10-2009
Production of amorphous carbon by plasma immersion ion implantation of polymers
Publisher: Elsevier BV
Date: 10-2005
Non-chromate deoxidation of AA2024-T3: Sodium bromate–nitric acid (20–60°C)
Publisher: Elsevier BV
Date: 03-2008
Ab initio study of structure in boron nitride, aluminum nitride and mixed aluminum boron nitride amorphous alloys
Publisher: AIP Publishing
Date: 11-2000
DOI: 10.1063/1.1316790
Abstract: Car–Parrinello molecular dynamics is applied to the liquid quench simulation of the amorphous networks of BN, AlN and AlBN2. Structural and elastic properties were determined. It is found that AlN has a stronger tendency to chemical order than BN, driven by the greater energy penalty for “wrong bonds.” AlN, however, has a stronger tendency to form an amorphous structure as judged by the energy difference between the crystalline and amorphous states. There is some experimental evidence for an amorphous form of AlN. BN was simulated at two densities, 2.0 and 3.0 g/cm3. Even at the higher density, the fraction of tetrahedral coordination remained low, in contrast to AlN, enabling us to predict that the tetrahedral amorphous form of BN does not form under liquid quench conditions. The amorphous network with the formula AlBN2 has an intermediate tendency to form a tetrahedral structure and has a relatively high elastic modulus. This material is predicted to be of value for application as a wear resistant coating.
Magnetic ordering and spin-glass behaviour of carbon nanoclusters
Publisher: IEEE
Date: 2006
Multilayer alumina and titania optical coatings prepared by atomic layer deposition
Publisher: SPIE
Date: 28-08-2008
DOI: 10.1117/12.794618
The role of pulse length in target poisoning during reactive HiPIMS: application to amorphous HfO2
Publisher: IOP Publishing
Date: 26-05-2015
Minimisation of intrinsic stress in titanium nitride using a cathodic arc with plasma immersion ion implantation
Publisher: Elsevier BV
Date: 09-2003
Molecular dynamics and experimental studies of preferred orientation induced by compressive stress
Publisher: Elsevier BV
Date: 12-1995
Ion implantation induced phase transformation in carbon and boron nitride thin films
Publisher: Elsevier BV
Date: 08-2005
Corrosion of AA2024-T3 Part II: Co-operative corrosion
Publisher: Elsevier BV
Date: 2011
The role of energetic ions from plasma in the creation of nanostructured materials and stable polymer surface treatments
Publisher: Elsevier BV
Date: 2006
The structure and electronic properties of tetrahedrally bonded hydrogenated amorphous carbon
Publisher: AIP Publishing
Date: 05-2023
DOI: 10.1063/5.0147494
Abstract: We have synthesized hydrogenated and deuterated amorphous carbon materials that have a density, 2.7 ± 0.1 g/cm3, consistent with almost entirely tetrahedral bonding. In hydrogen-free tetrahedral amorphous carbon, the presence of a minority of sp2 bonded atoms leads to localized states that could be passivated with hydrogen by analogy with hydrogenated amorphous silicon. Neutron diffraction analysis demonstrated that the local bonding environment is consistent with ab initio models of high density hydrogenated tetrahedral amorphous carbon and with the related tetrahedral molecular structure neopentane. The optical bandgap of our material, 4.5 eV, is close to the bandgap in the density of states determined by scanning tunneling spectroscopy (4.3 eV). This bandgap is considerably larger than that of hydrogen-free tetrahedral amorphous carbon, confirming that passivation of sp2 associated tail-states has occurred. Both the structural and electronic measurements are consistent with a model in which the tetrahedrally bonded carbon regions are terminated by hydrogen, causing hopping conductivity to dominate.
Extending the Debye scattering equation for diffraction from a cylindrically averaged group of atoms: detecting molecular orientation at an interface
Publisher: International Union of Crystallography (IUCr)
Date: 20-05-2020
DOI: 10.1107/S2053273320005276
Abstract: The Debye scattering equation is now over 100 years old and has been widely used to interpret diffraction patterns from randomly oriented groups of atoms. The present work develops and applies a related equation that calculates diffraction intensity from groups of atoms randomly oriented about a fixed axis, a scenario that occurs when molecules are oriented at an interface by the presentation of a binding motif as in antibody binding. Using an ex le biomolecule, the high level of sensitivity of the diffraction pattern to the orientation of the molecule and to the direction of the incident beam is shown. The use of the method is proposed not only for determining the orientation of molecules in biosensors and at membrane interfaces, but also for determining molecular conformation without the need for crystallization.
Evolution of target condition in reactive HiPIMS as a function of duty cycle: An opportunity for refractive index grading
Publisher: AIP Publishing
Date: 07-03-2017
DOI: 10.1063/1.4977824
Abstract: Competition between target erosion and compound layer formation during pulse cycles in reactive HiPIMS opens up the possibility of tuning discharge conditions and the properties of deposited films by varying the duty cycle in situ without altering the reactive gas mixture. Three different reactive systems, hafnium in oxygen, tungsten in oxygen, and tungsten in oxygen/nitrogen, are studied in which amorphous films of hafnium oxide (HfO2), tungsten oxide (WO3), and tungsten oxynitride (WOxNy) are deposited. We show that the cyclic evolution of the target surface composition depends on the properties of the target including its affinity for the reactive gas mix and the compound layer melting point and volatility. We find that pulse length variations modulate the target compound layer and hence the discharge chemistry and properties of the films deposited. The refractive indices of HfO2 and WO3 were progressively reduced with the duty cycle, whereas that of WOxNy increased. These variations were found to be due to changes in the chemical composition and/or densification. We present and validate a phenomenological model that explains these findings in terms of a compound layer on the target surface that undergoes evolution during each pulse resulting in a cyclic equilibrium. The end points of the composition of the target surface depend on the duty cycle. Tuning the pulse characteristics holds great promise for the fabrication of multilayer films with through thickness graded properties.
The mechanical response of glassy carbon recovered from high pressure
Publisher: AIP Publishing
Date: 14-04-2020
DOI: 10.1063/1.5142309
Abstract: Glassy carbon (GC) is usually considered the prototypical super-elastic material, which can almost fully recover its shape after compression of several gigapascals (GPa). In this work, nanoindentation is used to study the mechanical response of GC, which was subjected to a range of high pressures using a diamond anvil cell (DAC). We show that GC starts to lose its elasticity after compression to 6 GPa and becomes clearly mechanically anisotropic after being compressed beyond ∼30 GPa. Molecular dynamics (MD) simulations are used to calculate Young's modulus before and after compression. Through our experimental results and MD simulations, we show that the elasticity of GC is at a minimum around 30 GPa but recovers after compression to higher pressures along the DAC compression axis.
Scaled-up production of multi-walled carbon nanotubes using catalytic chemical vapour deposition
Publisher: IEEE
Date: 07-2006
Optically absorbing trilayer films fabricated using a Filtered Cathodic Vacuum Arc
Publisher: Wiley
Date: 29-05-2008
THE ELECTRONIC STRUCTURE AND MEMORY DEVICE APPLICATIONS OF TETRAHEDRAL AMORPHOUS CARBON
Publisher: World Scientific Pub Co Pte Lt
Date: 30-01-2000
DOI: 10.1142/S0217979200000236
Abstract: The introduction of nitrogen dopant sites into tetrahedral amorphous carbon produces changes in the structure and the electronic density of states that can be modelled using molecular dynamics. In this work we use both a tight-binding approach and a Car-Parrinello density functional theory approach. In a comparison of these, we found that the former tends to overestimate the strain energy of 3 membered carbon rings relative to the latter and to experiment, explaining the reduced occurrence of 3 membered rings in networks and simulated using tight-binding. Experiment shows that at approximately 3% of nitrogen, the network begins to change rapidly with nitrogen content. In this form, an additional electronic conduction mode is found experimentally, of the Poole-Frenkel type, which can be turned on and off at will. The conduction is turned on by negative voltage excursion and quenched by a positive one. This conduction bistability can be exploited to produced a simple new type of memory device in which the high conductivity state (''on'') is a digital ''1'' and the low conductivity state (''off'') is a digital ''0''. The operating characteristics of the device are excellent, with more than one million read cycles having been demonstrated without deterioration of the discrimination between the ''on'' and ''off'' states. Molecular dynamics is used to study the configuration of the nitrogen atoms, yielding a possible candidate for the site responsible for the Poole-Frenkel conduction.
Synthesis of highly tetrahedral amorphous carbon by mixed-mode HiPIMS sputtering
Publisher: IOP Publishing
Date: 09-10-2015
Characterization of cathodic arc deposited titanium aluminium nitride films prepared using plasma immersion ion implantation
Publisher: IOP Publishing
Date: 15-04-2005
Dark field microscopy for diffraction analysis of amorphous carbon solids
Publisher: Elsevier BV
Date: 03-2005
Positive magnetisation in carbon nanoclusters produced by high-repetition-rate laser ablation
Publisher: Springer Science and Business Media LLC
Date: 2007
Abstract: Carbon nanoclusters produced by high-repetition-rate laser ablation of graphite and glassy carbon in Ar exhibits para- and ferromagnetic behaviour at low temperature. The results show that the degree of remanent order is strongly dependent on the magnetic history, i.e. whether the s les were cooled under zero-field or field conditions. Such behaviour is typical for a spin glass structure where the system can exist in many different roughly equivalent spin configurations. The spin-freezing temperature is unusually high (50–300 K) compared with ≤ 15 K for typical spin glasses. The maximum in the zero-field magnetic susceptibility experiments and their field dependence indicate that there is competition between ferromagnetic and antiferromagnetic exchange pathways, accounting for the spin glass behavior and/or a low-dimensionality of the system.
ITO-free silver-doped DMD structures: HiPIMS transparent-conductive nano-composite coatings for electrochromic applications
Publisher: Elsevier BV
Date: 10-2021
The mechanical properties of energetically deposited non-crystalline carbon thin films
Publisher: Elsevier BV
Date: 03-2016
Room-Temperature Negative Differential Resistance in Amorphous Carbon: The Role of Electron Trapping Defects at Device Interfaces
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 02-2021
Control of stress and microstructure in cathodic arc deposited films
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 10-2003
Controlled glow to arc transition in sputtering for high rate deposition of carbon films
Publisher: Elsevier BV
Date: 02-2011
Aluminium/aluminium oxide nanocomposites prepared using a filtered cathodic vacuum arc
Publisher: Elsevier BV
Date: 08-2012
The effect of plasma immersion ion implantation on the contact pressure and composition of titanium nitride thin films
Publisher: Elsevier BV
Date: 09-2006
The shear-driven transformation mechanism from glassy carbon to hexagonal diamond
Publisher: Elsevier BV
Date: 02-2019
Wannier function analysis of tetrahedral amorphous networks
Publisher: Elsevier BV
Date: 10-2003
SEM and RBS characterization of a cobalt-based conversion coating process on AA2024-T3 and ALA7075-T6
Publisher: Wiley
Date: 2004
DOI: 10.1002/SIA.1986
Ultraviolet and visible Raman analysis of thin a-C films grown by filtered cathodic arc deposition
Publisher: Elsevier BV
Date: 05-2010
A hydrogen gas sensor based on Pt/nanostructured WO3 /SiC Schottky diode
Publisher: American Scientific Publishers
Date: 02-2011
DOI: 10.1166/SL.2011.1409
The morphology and structure of sol–gel derived zirconia films on stainless steel
Publisher: Elsevier BV
Date: 12-1997
Comparison of density-functional, tight-binding, and empirical methods for the simulation of amorphous carbon
Publisher: American Physical Society (APS)
Date: 25-01-2002
SAW Gas Sensors with Titania Nanotubes Layers
Publisher: American Scientific Publishers
Date: 04-2011
DOI: 10.1166/SL.2011.1645
SAW Gas Sensors with Metal Oxides Nanoplatelets Layers
Publisher: American Scientific Publishers
Date: 04-2011
DOI: 10.1166/SL.2011.1644
The structural phases of non-crystalline carbon prepared by physical vapour deposition
Publisher: Elsevier BV
Date: 11-2009
Gas sensing properties of interconnected ZnO nanowires
Publisher: American Scientific Publishers
Date: 04-2011
DOI: 10.1166/SL.2011.1646
Structural analysis of carbonaceous solids using an adapted reverse Monte Carlo algorithm
Publisher: Elsevier BV
Date: 2003
Ab initio studies of amorphous carbon films
Publisher: Elsevier BV
Date: 08-2005
Sensory gating in bilayer amorphous carbon memristors
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8NR05328F
Abstract: Paired pulse inhibition is observed using amorphous carbon memristors, which enables their use for sensory gating.
The structure and annealing properties of multilayer carbon films
Publisher: Elsevier BV
Date: 08-2005
The anodized crystalline WO3 nanoporous network with enhanced electrochromic properties
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2NR31203D
Abstract: We demonstrate that a three dimensional (3D) crystalline tungsten trioxide (WO(3)) nanoporous network, directly grown on a transparent conductive oxide (TCO) substrate, is a suitable working electrode material for high performance electrochromic devices. This nanostructure, with achievable thicknesses of up to 2 μm, is prepared at room temperature by the electrochemical anodization of a RF-sputtered tungsten film deposited on a fluoride doped tin oxide (FTO) conductive glass, under low applied anodic voltages and mild chemical dissolution conditions. For the crystalline nanoporous network with thicknesses ranging from 0.6 to 1 μm, impressive coloration efficiencies of up to 141.5 cm(2) C(-1) are achieved by applying a low coloration voltage of -0.25 V. It is also observed that there is no significant degradation of the electrochromic properties of the porous film after 2000 continuous coloration-bleaching cycles. The remarkable electrochromic characteristics of this crystalline and nanoporous WO(3) are mainly ascribed to the combination of a large surface area, facilitating increased intercalation of protons, as well as excellent continuous and directional paths for charge transfer and proton migration in the highly crystalline material.
Codeposition of amorphous zinc tin oxide using high power impulse magnetron sputtering: characterisation and doping
Publisher: IOP Publishing
Date: 21-03-2017
Identification of M5C2 carbides in ex- service 1Cr-0.5Mo steels
Publisher: Springer Science and Business Media LLC
Date: 03-1995
DOI: 10.1007/BF02663901
Influence of point defects on the near edge structure of hexagonal boron nitride
Publisher: American Physical Society (APS)
Date: 11-10-2017
The influence of deposition rate on the stress and microstructure of AlN films deposited from a filtered cathodic vacuum arc
Publisher: Elsevier BV
Date: 03-2011
Control of stress and delamination in single and multi-layer carbon thin films prepared by cathodic arc and RF plasma deposition and implantation
Publisher: Elsevier BV
Date: 06-2006
Ab initiosimulation of structure in amorphous hydrogenated carbon
Publisher: American Physical Society (APS)
Date: 08-2000
New measurement of melting and thermal conductivity of iron close to outer core conditions
Publisher: Elsevier BV
Date: 03-2020
An investigation of the native oxide of aluminum alloy 7475-T7651 using XPS, AES, TEM, EELS, GDOES and RBS
Publisher: World Scientific Pub Co Pte Lt
Date: 04-2003
DOI: 10.1142/S0218625X0300530X
Abstract: The native oxide on the rolled aerospace aluminum alloy 7475-T7651 was characterized using a variety of different techniques, including X-ray Photoelectron Spectrometry (XPS), Auger Electron Spectrometry (AES), Transmission Electron Microscopy (TEM), Electron Energy Loss Spectrometry (EELS), Glow Discharge Optical Emission Spectrometry (GDOES), and Rutherford Backscattered Spectrometry (RBS). All techniques revealed that the native oxide layer is magnesium-rich and is probably a mixture of magnesium and aluminum–magnesium oxides. 1 The oxide layer was found to be of nonuniform thickness due to the rolling process involved during the manufacture of this sheet alloy this complicates analysis using techniques which have poor spatial resolution. Direct thickness measurement from cross-sectional TEM reveals an oxide thickness which varies between 125 and 500 nm. This large variation in thickness was also evident from GDOES and AES depth profiles as well as the RBS data. Both XPS and RBS also show evidence for the presence of heavy metals in the oxide.
A comparison of experimental and calculated electron-energy loss near-edge structure of carbon, and the nitrides of boron, carbon and silicon using multiple scattering theory
Publisher: Elsevier BV
Date: 09-1998
Stable n-channel metal-semiconductor field effect transistors on ZnO films deposited using a filtered cathodic vacuum arc
Publisher: AIP Publishing
Date: 10-12-2012
DOI: 10.1063/1.4769899
Abstract: We report on the properties of metal-semiconductor-field-effect-transistors (MESFETs) on ZnO films grown using the filtered cathodic vacuum arc (FCVA) technique. FCVA ZnO films deposited on a-plane sapphire at 200 °C showed good structural and electrical properties that improved further on annealing at 800 °C in oxygen, due to the formation of larger grains with lower inter-grain transport barriers. MESFETs with silver oxide and iridium oxide Schottky gates on these annealed films showed excellent long-term stability with low ideality factors (& .3), low gate leakage, and channel mobilities up to 50 cm2/Vs that were unchanged with both age and stress testing.
Structural investigation of two carbon nitride solids produced by cathodic arc deposition and nitrogen implantation
Publisher: AIP Publishing
Date: 05-1996
DOI: 10.1063/1.361515
Abstract: Carbon nitride materials have been the focus of research efforts worldwide. Most materials studied have been amorphous, with only a few groups claiming to have found a crystalline material. We investigate the structure of amorphous carbon nitride solids produced by two different techniques: cathodic arc deposition and high dose nitrogen implantation of glassy carbon. Transmission electron microscopy, electron energy loss spectroscopy, energy filtered electron diffraction, Rutherford backscattering, infrared, and Raman spectroscopy are all used to derive structural information. It was found that the carbon nitride materials prepared by both techniques have similar structures and [N]/[C] ratios (0.3). The materials appear to have a primarily sp2 bonded carbon structure with a smaller bond length than found in amorphous carbon. This is explained by nitrogen substituting into ‘‘rings’’ to a saturation level of about one nitrogen per three carbon atoms. We have found no evidence for a C3N4 crystalline structure, nor any amorphous derivative of it.
The relationship between microstructure and electrical breakdown in cathodic arc deposited hafnium oxide films
Publisher: AIP Publishing
Date: 07-2011
DOI: 10.1063/1.3607238
Abstract: Hafnium oxide films were deposited with a range of substrate temperatures using a filtered cathodic vacuum arc deposition system. The microstructure, electronic structure, and electrical breakdown of the films were characterized. In films deposited at temperatures above 200 °C, the microstructure became more ordered and x-ray diffraction indicated that the dominant phase was monoclinic hafnium oxide. Evidence for the presence of the tetragonal phase was also found in the films deposited at temperatures above 400 °C. The near edge structure of the oxygen K-edge measured using x-ray absorption spectroscopy, provided further evidence that films prepared at high temperatures contained a combination of the monoclinic and tetragonal phases. Films deposited at room temperature were disordered and exhibited the best electrical breakdown characteristics. The electrical breakdown of the films deteriorated as the crystallinity increased with increasing deposition temperature. These results support the proposition that electrical breakdown paths may occur along grain boundaries in polycrystalline hafnium oxide films and therefore a disordered microstructure is preferable.
Nanoporous TiO2 thin film based conductometric H2 sensor
Publisher: Elsevier BV
Date: 12-2009
A physical and spectroscopic study of polypyrrole films containing tetrasulfonated metallophthalocyanine and transition metal EDTA chelates
Publisher: Elsevier BV
Date: 03-1995
The electronic structure of tungsten oxide thin films prepared by pulsed cathodic arc deposition and plasma-assisted pulsed magnetron sputtering
Publisher: IOP Publishing
Date: 07-04-2008
Energetic deposition of carbon in a cathodic vacuum arc with a biased mesh
Publisher: AIP Publishing
Date: 04-2011
DOI: 10.1063/1.3562165
Abstract: Carbon films were deposited in a filtered cathodic vacuum arc with a bias potential applied to a conducting mesh mounted in the plasma stream between the source and the substrate. We determined the stress and microstructural properties of the resulting carbon films and compared the results with those obtained using direct substrate bias with no mesh. Since the relationship between deposition energy and the stress, sp2 fraction and density of carbon are well known, measuring these film properties enabled us to investigate the effect of the mesh on the energy and composition of the depositing flux. When a mesh was used, the film stress showed a monotonic decrease for negative mesh bias voltages greater than 400V, even though the floating potential of the substrate did not vary. We explain this result by the neutralization of some ions when they are near to or passing through the negatively biased mesh. The microstructure of the films showed a change from amorphous to glassy carbonlike with increasing bias. Potential applications for this method include the deposition of carbon films with controlled stress on low conductivity substrates to form rectifying or ohmic contacts.
Uniformly Dispersed Pt−Ni Nanoparticles on Nitrogen-Doped Carbon Nanotubes for Hydrogen Sensing
Publisher: American Chemical Society (ACS)
Date: 11-12-2009
DOI: 10.1021/JP908945X
Hardness of nano- and microcrystalline lonsdaleite
Publisher: AIP Publishing
Date: 20-02-2023
DOI: 10.1063/5.0138911
Abstract: Lonsdaleite is a hexagonal allotrope of carbon found in nature in meteorites and at meteorite impact sites. It has been predicted to have an indentation hardness greater than cubic diamond by first principles calculations. However, this has not been demonstrated experimentally. Here, nanoindentation was used to measure the hardness of two different lonsdaleite s les. One contains nanocrystalline lonsdaleite synthesized by high pressure compression of glassy carbon. The other is from a ureilite meteorite that contains lonsdaleite crystals up to ∼1 μm. The hardness of these two s les was determined using both the Oliver–Pharr and Meyer methods. Our results show that the hardness of the lonsdaleite s les is similar to that of diamond therefore, there is no evidence that these forms of polycrystalline lonsdaleite are significantly harder than similar forms of diamond.
Analysis of nanocrystalline diamond powder by scanning transmission electron microscopy
Publisher: AIP Publishing
Date: 06-2001
DOI: 10.1063/1.1360702
Abstract: Theoretical studies [R. P. Fehlhaber and L. A. Bursill, Phys. Rev. B 60, 14147 (1999)] of small nanocrystalline diamond spheres, using the classical electrodynamic formalism with a well defined impact parameter and including all multipole modes, are used to analyze and discuss electron energy loss spectra recorded with a high resolution scanning transmission electron microscope. The theory is used to predict spectra for spheres of different radii with and without surface coatings. Due to the relatively large d ing factor for diamond the surface, interface and bulk plasmon peaks overlap but it is shown that the theory is nevertheless capable to allow particle diameter and coating thickness to be determined accurately. The theory is also applied to make some deductions concerning particle morphology by analysis of low-loss spectra from particles of different thickness and shape.
A study of Technegas employing X-ray photoelectron spectroscopy, scanning transmission electron microscopy and wet-chemical methods
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-1996
DOI: 10.1097/00006231-199606000-00009
Abstract: Scanning transmission electron microscopy (STEM), coupled with energy dispersive X-ray analysis (EDS), X-ray photoelectron spectroscopy (XPS) or radionuclear chemical methods, indicates that the active agent in Technegas is either polymeric TcO2[i.e. (TcO2)n] or (TcO2)n bound to a carbon nanoparticle. The particle size observed using STEM is in good agreement with other published results. XPS has also been used to investigate technetium residues remaining on spent crucibles. The chemical form of technetium in this residue is quite different to the form detected in the aerosol particles. We conclude that the small fraction that migrates into the crucible framework upon resistive heating is reduced to either metallic technetium or carbidic forms, with the remaining nuclide evaporating as (TcO2)n with or without carbon before complete reduction can occur.
Hard magnetic properties in nanoflake van der Waals Fe3GeTe2
Publisher: Springer Science and Business Media LLC
Date: 19-04-2018
DOI: 10.1038/S41467-018-04018-W
Abstract: Two-dimensional van der Waals materials have demonstrated fascinating optical and electrical characteristics. However, reports on magnetic properties and spintronic applications of van der Waals materials are scarce by comparison. Here, we report anomalous Hall effect measurements on single crystalline metallic Fe 3 GeTe 2 nanoflakes with different thicknesses. These nanoflakes exhibit a single hard magnetic phase with a near square-shaped magnetic loop, large coercivity (up to 550 mT at 2 K), a Curie temperature near 200 K and strong perpendicular magnetic anisotropy. Using criticality analysis, the coupling length between van der Waals atomic layers in Fe 3 GeTe 2 is estimated to be ~5 van der Waals layers. Furthermore, the hard magnetic behaviour of Fe 3 GeTe 2 can be well described by a proposed model. The magnetic properties of Fe 3 GeTe 2 highlight its potential for integration into van der Waals magnetic heterostructures, paving the way for spintronic research and applications based on these devices.
Vacuum heat treatment of high speed steel cutting tools
Publisher: Informa UK Limited
Date: 09-2013
Ultraviolet detection from energetically deposited titania films
Publisher: AIP Publishing
Date: 31-03-2014
DOI: 10.1063/1.4870069
Abstract: Thin films of unintentionally doped n-type titania have been energetically deposited from a filtered cathodic vacuum arc. All films were dense, smooth, and transparent with crystallinity depending on the deposition/annealing temperature. At a growth temperature of 600 °C, the preferred phase could be changed from rutile to anatase by increasing the oxygen process pressure thereby reducing dynamic annealing. Pt/TiOx/Pt ultraviolet detectors exhibiting rectifying current-voltage characteristics and ultraviolet-visible rejection ratios exceeding 104:1 were formed on selected films.
Stress relief and texture formation in aluminium nitride by plasma immersion ion implantation
Publisher: IOP Publishing
Date: 03-2004
Microstructural and tribological characterisation of a nitriding/TiAlN PVD coating duplex treatment applied to M2 High Speed Steel tools
Publisher: Elsevier BV
Date: 06-2015
Ab initiosimulations of the structure of amorphous carbon
Publisher: American Physical Society (APS)
Date: 15-01-2000
Cross-sectional transmission electron microscopy investigation of xenon irradiated glassy carbon
Publisher: Elsevier BV
Date: 1993
Structural and dielectric properties of energetically deposited hafnium oxide films
Publisher: IOP Publishing
Date: 13-11-2014
Hafnium oxide thin films deposited from a filtered cathodic vacuum arc
Publisher: Springer Science and Business Media LLC
Date: 09-05-2009
Quantitative, nanoscale mapping of sp2 percentage and crystal orientation in carbon multilayers
Publisher: Elsevier BV
Date: 2009
Ab initiosimulations of amorphous carbon nitrides
Publisher: American Physical Society (APS)
Date: 19-12-2001
Theory of momentum-resolved phonon spectroscopy in the electron microscope
Publisher: American Physical Society (APS)
Date: 11-03-2019
An energy landscape for carbon network solids
Publisher: Elsevier BV
Date: 11-2013
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