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Please note: The PhD studentships are available and linked to, but not directly part of, the NanoLAB Centre. These studentships are available for UK citizens, and partial funding may be available for EU students

  1. Real-time characterisation of nanoscale frictional processes

    Supervisors: BJ Inkson

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    Tribology processes such as friction and wear affect all technology with moving parts. Although many friction and wear mechanisms occur at the nanoscale, it is extremely difficult to investigate how they happen in real time. Here at Sheffield NanoLAB we have built a new mechanical triboprobe miniaturized to fit inside a TEM which will enable two surfaces to be videoed as they rub against each other, and enable real-time characterisation of nanofriction and nanowear. In two available projects the TEM triboprobe will be used for ground-breaking research into the frictional and wear processes of (a) industrially important carbon-based lubricants and (b) ultrathin surface coatings systems. The microstructural changes and conversion of energy occurring during nanoscale impacts of individual lubricant particles, and frictional nanocontacts between rubbing surfaces, will be characterised in real-time using high resolution advanced ion and electron microscopy techniques
  2. New methods for welding at the nanoscale

    Supervisors: BJ Inkson

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    One of the central challenges for the construction, integration and repair of nanoscale systems is to develop reliable methods of joining individual nanoobjects together and to substrates. Although a number of localized joining methods suitable for individual nanoscale objects have recently been proposed, including thermal heating and ion beam deposition of material, they generally lead to some degradation of the nanostructure involved. In this project we will develop a new nanoscale electrical welding technique, using nanovolumes of metal solder, which should radically improves the spatial resolution, flexibility and controllability of nanoscale joins and welds. The use of solder to bond nanoobjects together should offer the opportunity to tailor the mechanical and functional properties of weld by controlling the chemistry, structure and volume of solder material used. The new nanoweld methods will be applied to the construction of novel 3D semiconductor nanowire circuits, whose structure and electrical performance will then be extensively characterized using real-time nanoprobe techniques. This work will be part of a large Basic Technology programme, and will be carried out in collaboration with industrial partners
  3. Wear and Degredation of MEMS components

    Supervisors: BJ Inkson

    In collaboration with QinetiQ, Malvern QinetiQ Website
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    Metal and ceramic wires and cantilevers smaller than a micron in size are being developed for use in micro- and nano-electromechanical system (MEMS and NEMS) devices. Surface wear and damage can be much more dangerous in such tiny components than for bulk samples. This project, with the MEMS centre at QinetiQ, Malvern, is to characterise the mechanisms of damage and wear in MEMS devices after specified fractions of projected lifetime. Damage build up from thermal/stress cycling and repeated material impact (wear at joints) will be characterised by advanced microscopy methods including real-time impact testing of nanocontacts in the TEM, site-specific FIB-TEM samples extracted from tested specimens, and 3D FIB/TEM microstructural analysis. The microstructural evolution will be linked to simple finite element modelling of the component deformation (QinetiQ), with the aim to design new damage resistant MEMS devices
  4. Novel magnetic and electronic nanowires: Fabrication and Characterisation

    Supervisors: BJ Inkson

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    Functional nanowires, possessing diverse and novel properties, can be fabricated by the billion in a beaker by using porous templates into which vast arrays of nanowires and nanotubes are grown by electrodeposition of materials into the pores. This project will involve the fabrication of novel magnetic and electronic nanowires by electrodeposition into porous alumina templates. The microstructure of the wires will be characterised by advanced electron microscopy, as a function of the wire width and length which can be varied by controlling the porous alumina template growth. Single nanowires will be functionally tested and assembled into prototype devices using novel in-situ TEM mechanical and electrical probes built under the Sheffield RCUK Nanorobotics programme. The performance and stability of the magnetic and electronic wires will investigated as a function of mictostructural parameters including grainsize, nanolayer sizes and nanoscale chemistry. The structural stability of the nanowires, specifically morphological transformations which can occur during current flow due Joule heating, will be investigated
  5. Nanofabrication of functional devices by ion implantation

    Supervisors: G Möbus

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    Ion implantation into substrates is a well established technology, e.g. for the doping of semiconductor device structures. At higher dose rates, the implanted atoms can accumulate with or without annealing to form clusters or entire nanoparticles. This opens up a new route of nanofabrication by tuning the particle size, the depth of implantation and the implantation dose. We use large scale ion implantation in collaboration with the Ion Beam Centre at Surrey University, and apply state-of-the-art aberration corrected electron microscopy for imaging. Application fields comprise e.g. data storage, sensor development, and other patterned media devices
  6. Looking inside Materials: Nanotomography and 3D Nanometrology

    Supervisors: G Möbus

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    Nanomaterials are intrinsically 3-dimensional materials, as their properties depend on surface-proximity and confinement of electronic or mechanical properties as low dimensional matter. Imaging of surfaces or planar cross-sections is no longer sufficient. In this project we develop new acquisition sequences and new data reconstruction procedures for applying the established technique of computed axial tomography (CAT) to nanomaterials, with special emphasis on 3D chemical and structural mapping. State-of-the-art aberration corrected electron microscopy is available for projection imaging. Applications will e.g. comprise nanoparticles, nanoparticle composites, functional nanotips and nanoporous materials
  7. Nanopatterning for engineering of novel devices and surfaces

    Supervisors: G Möbus

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    We use electron beams to drill or cut patterns with sub 5nm dot resolution into inorganic substrates. The research concentrates especially on the physical origins of the ultimate resolution limit of this technique and the chemical processes taking place during ablation of atoms. A second central aim of the project is to study sublattice depletion (such as to remove anions only from a compound) to leave conductive or magnetic purely metallic material behind. Another aspect is the analysis of freshly milled patterns via nanoscale spectroscopy inside the transmission electron microscope. Prospective applications include nano-circuitry, nano-optics, patterns for nanoscale templating
  8. Experimental study of nanoparticle architectures

    Supervisors: G Möbus and BJ Inkson

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    Nanoparticles can be obtained in various degrees of agglomeration or clustering. Cluster morphologies and orientation relationships are to be established via electron diffraction and transmission electron microscopy imaging, including aberration corrected TEM. Experimental data from TEM are to be compared with modelling data (in collaboration with Cranfield University). The dependency of properties on the degree of order or type of clustering is to be established. Application relevant fields of this project comprises: catalysis, sensors, batteries/energy devices, and mechanical processing tools
  9. Irradiation induced materials transformations

    Supervisors: G Möbus and Dr. M.I. Ojovan

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    Live observation of materials changing under irradiation using electron microscopy have recently allowed the discovery of novel phenomena of nanoscale phase and morphology transformations. The project will mainly deal with multi-component silicate glasses, and explore the relationships between chemical composition, processing geometry and/or temperature and the transformations achieved. Examples of such transformations comprise the formation of perfect glass beads out of randomly shaped fragments, the perforation of thin films, gas bubble formation, as well as phase separation and crystallization. The study’s importance lies in possible applications for 3D device packaging, nanoscale pattern formation, as well as for irradiation stability of glasses and ceramics loaded with radionuclides
  10. Local chemistry analysis via EELS spectroscopy for oxide glasses and ceramics

    Supervisors: G Möbus and Dr. R.J. Hand

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    Physical and chemical properties of glasses and ceramics often depend on the coordination and valence states of functional doping atoms or other functional cations. In this project, the technique of electron energy loss spectroscopy in the electron microscope is used to spatially map the distribution of coordination and valence parameters in a selection of glasses and ceramic materials (e.g. glass/nanoparticle composites). Individual topics can be tailored e.g. to include borosilicate glasses, or diamond like carbon coatings
  11. Computational simulation of the imaging process for atomic resolution aberration corrected TEM of nanoparticles

    Supervisors: G Möbus

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    Using latest equipment in the field of transmission electron microscopy, small particles can be mapped for structural and morphology changes down to a single monolayer or atom. The interpretation of images however often requires the understanding of the image formation process from a viewpoint of electron waves. In this project existing computer simulation software shall be used to predict and model the formation of images and diffraction patterns for the new Sheffield aberration corrected TEM facility (Kroto Institute). The project is complemented by post-processing computational evaluation of digital experimental micrographs of nanoparticles, and the student will participate in assisted imaging sessions to generate test data
  12. Development of Nanotools for TEM Nanoroboitcs

    Supervisors: BJ Inkson

    In collaboration with Nottingham University University of Nottingham Website
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    The development of nanorobotics (material nanomanipulation and testing under severe spatial constraints) has important implications for many areas of nanotechnology. We have developed a novel miniaturised piezo-controlled nanopositioning system which fits into an electron microscope. To this nanopositioning system, there is the possibility to fix many different types of nanotools and nanosensors to measure materials properties at the nanometre level whilst simultaneously observing with the electron microscope. This project will involve developing novel nanorobotics nanotools (functionalised tips/probes) optimised for a variety of exciting applications including (i) picking up nanoscale volumes/molecules (nanogrippers), (ii) depositing material/molecules (nanopens), (iii) generating local deformation (nanoindentation) and (iv) making local electrical measurements (nano-electrodes)
  13. Novel Quantum Computing Device Fabrication and Testing

    Supervisors: BJ Inkson and Prof A.G. Cullis

    In collaboration with QinetiQ, Malvern QinetiQ Website
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    A revolution in nanomanipulation systems for electron microscopes is enabling unique devices to be manufactured by the nanopositioning of molecules and nanoobjects within specially designed electrode/electronic frameworks. This exciting project involves the design, fabrication and testing of novel quantum computing devices which spatially confine electrons in 1D and 2D systems. The nanoscale active components, including carbon fullerenes/ nanotubes and metallic wires, will be positioned between electrodes in-situ within electron microscopes (SEM/FIB/TEM) with real-time observation of the device fabrication process
  14. Nanomaterials in Action: In-situ Alloying at the Nanoscale

    Supervisors: BJ Inkson and Prof. J.H. Harding

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    Understanding the physical processes by which metals interact in the solid state to form alloys are of vital importance in the development of new ultraperformance aerospace alloys and metallic components of micro- and nano-electromechanical system (MEMS and NEMS) devices. Not well understood is how the change from xbulkx to xnanoscalex systems changes the dynamics and equilibrium of metal alloying processes. This project aims to characterise, uniquely both experimentally and theoretically, the dynamical interaction and reaction of metals (initially Ti-Al and Ni-Al) at the nanoscale. Two metals will be brought into contact within an electron microscope, using a unique electron microscope nanomanipulation system built at Sheffield. The structural, chemical and electrical changes at the metal-metal nanoscale bond will be recorded on video at a scale of 1 nanometre (a millionth of a millimetre!) and the chemical reaction zone quantified by state-of the art spectroscopy/diffraction/tomography techniques. For the chosen systems the possible phases of bulk metal alloys will be calculated as a function of temperature and composition. Dynamical simulations will then be performed of the in-situ alloying process to investigate the atomic-scale mechanisms at the metal-metal interface and identify any new phases in conjunction with the experiments. The nanoscale results will be compared with the phase behaviour expected from consideration of the bulk phases
  15. Novel Magnetic Nanowires: Fabrication and Characterisation

    Supervisors: BJ Inkson and Prof. T. Schrefl

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    Under carefully controlled conditions the anodic oxidation of aluminium can result in an alumina thin film containing a self-assembled array of high aspect ratio nanopores. Functional nanowires, possessing diverse and novel properties, can be fabricated by the billion in a beaker by using the xporous aluminax as a template into which vast arrays of nanowires and nanotubes are grown by electrodeposition of materials into the self-ordered pores. This project will involve the fabrication of novel magnetic nanowires by electrodeposition into porous alumina templates. The microstructure of the wires will be characterised by advanced electron microscopy, as a function of the wire width and length which can be varied by controlling the porous alumina template growth. Single nanowires will be functionally tested and assembled into prototype devices using novel in-situ TEM mechanical and electrical probes built under the Sheffield RCUK nanorobotics programme. The structure and performance of the magnetic wires will be compared to theoretical models; the interplay between the crystallographic structure and the magnetic properties will be calculated using finite element simulations. In particular the interaction of magnetic domain walls with grain boundaries will be studied
  16. Nanofilled Composites for Medical and Dental Applications: Mechanical Failure at the Nanoscale

    Supervisors: BJ Inkson and Prof. P. Hatton

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    Biocompatible ceramic-polymer composites are used extensively in medicine and dentistry for human tissue repair. More recently, nanoparticles have been employed in the production of novel composites with the intention of improving their properties (e.g. wear resistance). Understanding the surface and interfacial properties of these functional materials at the nanoscale is very important for their molecular design. At Sheffield we are quantifying the nanomechanical and nanotribological properties of biocompatible ceramic-polymer nanocomposites using advanced microstructural techniques including state-of-the-art 3D tomographic analysis and wear testing inside electron microscopes. While the limited data available suggests that these nanostructured biomaterials have improved wear characteristics, the properties appear to be strongly influenced by the size, shape and distribution of the nanoparticles. The aim of this PhD programme is therefore to carry out a detailed study of the nanoscale properties and failure modes of these novel nanofilled medical and dental composite materials
  17. Thermal Stability of Direct-Write Nanostructures Deposited by Focused Ion and Electron Beams

    Supervisors: BJ Inkson

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    New direct-write technologies enable complex nanostructures to be directly written onto surfaces without the need for traditional multi-step lithographic based nanodeposition processes. One method involves the use of a highly focused beam of Ga+ ions (FIB) or electrons (SEM) to locally breakdown organic molecules on a surface ? leaving behind the desired metal or ceramic atoms only in the places the ion or electron beam have been. Because the ion or electron beam can be scanned in any pattern, nanostructures ranging from single nanoscale electrodes to large scale patterns can be written on a surface. Not much is known about the thermal stability of FIB and e-beam direct-write deposits, and this is a crucial issue for their use in the electronics industry for depositing, joining and repairing nanoscale components. This project will quantify the thermal stability of metallic and ceramic based FIB and e-beam direct-write components. Changes in microstructure after thermal cycling (morphology, crystallinity, chemistry + substrate reactions), including in-situ real-time thermal testing in electron microscopes, will be characterised by a range of state-of-the-art FIB and TEM techniques
  18. Quantitative Three Dimensional Dopant Mapping in the Scanning Electron Microscope

    Supervisors: C Rodenburg and BJ Inkson

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    Doping is the heart of all semiconductor devices because the number and position of dopant atoms determines the functionality of electronic devices. The aim of this project is to develop a high resolution, 3D dopant mapping technique that combines Focused Ion Beam specimen preparation with secondary electron spectroscopy in the Scanning Electron Microscope
  19. Manipulation of Micro and Nano Objects by Charge Writing in the Low Voltage Scanning Electron Microscope

    Supervisors: C Rodenburg and BJ Inkson

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    The contact-free controlled manipulation of micro and nano objects by electro static forces is of increasing interest because at the nano-scale objects tend to stick to surfaces they touch. The necessary electrostatic fields can be achieved by wiring charged patterns in substrates with the electron beam in a Low Voltage Electron Microscope