| Professor J Harding |
| 90 |
SIMULATING NANOSTRUCTURES: A MULTISCALE PROBLEM
Supervisor: Professor J Harding |
| Nanostructures such as quantum dots, carbon nanotubes, nanowires, ultra-thin films are sometimes small enough that one can hope to simulate the entire system. The problem is then that the timescale of the processes you are interested is too long for any simulation to manage. Dynamical simulations last of the order of hundreds of nanoseconds. Processes like diffusion, film growth, self-assembly can take place on timescales of seconds to years. There is no possibility of a direct simulation unless special methods are used. A range of these have been and are being developed. This project would work in collaboration with Prof. Bill Smith (Daresbury) and Prof Mark Rodger (Warwick) who are currently developing long timescale codes for the new HECTOR machine in Edinburgh. Depending on your interests, this project could either focus on the development of codes, or their applications to nanostructures, or both. |
| Dr B J Inkson |
| 91 |
WEAR AND DEGRADATION OF MEMS COMPONENTS
Supervisor: Dr B J Inkson (in collaboration with QinetiQ, Malvern) |
| 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. |
| 92 |
NOVEL MAGNETIC NANOWIRES: FABRICATION AND CHARACTERISATION
Supervisors: Dr B J Inkson and Professor T Schrefl |
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 ‘porous alumina’ 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. |
| 93 |
DEVELOPMENT OF NANOTOOLS FOR TEM NANOROBOTICS
Supervisor: Dr B J Inkson (in collaboration with Nottingham University) |
| 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). |
| Dr G Möbus |
| 94 |
ION-IMPLANTATION AND NANOPATTERNING STUDIES FOR FUNCTIONAL CERAMICS
Supervisors: Dr G Möbus |
| The processes of pattern formation for applications in nanotechnology in crystalline, and amorphous substrates upon various forms of irradiation is examined: (i) High-energy ion implantation in large scale accelerator facilities, (ii) low energy ion implantation in focused ion beam microscopy, (iii) highly focused electron beam irradiation in scanning transmission electron microscopy. Aim of the studies is to explore the physical/chemical processes involved in the pattern formation, to assess resolution limits, and to explore the writing of advanced patterns, such as lines, rings, and arrays of particles. Sheffield’s new aberration corrected TEM/SEM as well as special facilities for electron tomography for 3D chemical mapping will be used. |
| 95 |
ABERRATION CORRECTED TEM FOR TOMOGRAPHY ON THE EXTREME NANOSCALE
Supervisors: Dr G Möbus |
| Developments of innovative procedures, to perform nanoscale 3D reconstruction and analysis of nanostructured materials is at the core of this group of PhD topics. The focus of the project can be tuned according to the preference of the student across the filds of (i) Experimental microscopy work using Sheffield’s new state-of-the-art aberration corrected TEM/SEM, (ii) computational developments and programming in data processing and reconstruction algorithms, (iii) applications of the techniques to selected groups of nanomaterials, to include (examples only) nanoparticle arrays, nanochannel porous membranes, metallic nanowire heterostructures, and (iv) the characterisation of freshly in-situ fabricated nanostructures using the method of electron beam ablation. |
| 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). |
| Dr G Möbus |
| 96 |
STRUCTURAL DISCOVERIES AND TARGETED DAMAGE THROUGH LOW ENERGY ELECTRONS
Supervisors: C. Rodenburg |
| Electron beams are widely exploited in materials processing and characterisation for example to visualise sample surfaces in scanning electron microscopes (SEMs). Yet, for some materials groups such as polymers & glasses SEMs are rarely used to investigate surfaces at the nanoscale because of the potential damage the electron beam may cause. You will work to gain an insight of the interaction of low energy electron beams with materials such as organic solar cell materials through the use of highly localised secondary electron spectroscopy in an SEM (pioneered here in Sheffield at the Sorby Centre for Electron Microscopy and Microanalysis, with the support of FEI company). This gives you the opportunity to investigate how selective detection of secondary electrons in SEMs can be exploited for the characterisation of beam sensitive materials to reveal information that is not accessible otherwise. Gaining insight in to damage will also enable you to study how deliberately inflicted damage aids the processing of novel nanostructures in polymers and/or glass and explore applications. |
