Graduate Research Projects in the SMF Group (PhD and MPhil Degrees)
Understanding the dynamical properties of bulk materials, and of individual atoms and molecules on surfaces, remain substantial physical challenges. In the SMF group, we aim to investigate the physics of such processes at the most fundamental level practical.
In the fracture part of the group, we study the response of bulk materials and have a particular focus on material response at high strain rates, using a range of experimental techniques. We have a world-wide reputation for scientific excellence in dynamic experimental work and fast diagnostics (such as high speed photography), and collaborate with a range of international industrial sponsors. In the surface part of the group, we study how atoms move on the nanoscale, and the structures they form on surfaces. These processes are fundamental to understanding processes as diverse as industrial catalysis, hydrogen storage and atmospheric and interstellar reactions occur on environmental particulates.
Across the group, we apply an exceptionally wide range of experimental techniques, from nano-scale imaging to macroscopic materials tests, and we have a strong emphasis on development of innovative experimental techniques. Our projects are primarily experimental, but the group also pursues a considerable computational modelling effort - ideal for those people wishing to focus on modelling or theory, while maintaining a grounding in experiment.
Application and Funding
Information about the application procedure is available on the departmental website. All projects are available to students applying for Departmental Quota Award studentships or other personal awards. In addition, there are a number of other studentships available for work in specific areas, and many projects have dedicated funding streams.
PhD Projects for 2016 Entry
Fundamental Steps in the Recycling of Greenhouse Gases (Dr J Ellis) (†)
Greenhouse gas reduction, and especially CO2 reduction, is one of the greatest challenges to our society. While physical means to capture CO2 exist and have been demonstrated, the lack of efficient ways to recycle that CO2 forms an obstacle that prevents the technology from being widely used to ease global warming. Copper mediated hydrogenation of CO2 to form methanol (“MeOH”) is one of the most promising reactions with respect to recycling of greenhouse gas emissions, as not only does it reduce CO2, it also offers alternative fuel production.
The aim of this project is to establish new nanoscience methods which will enable the dynamics of CO2 and methanol to be studied on copper surfaces. Understanding the mobility of reactants and products is a critical step in CO2 conversion and using He spin-echo spectrometry (HeSE), which will be the focus of this project, is an ideal tool. HeSE allows for detailed dynamical analysis and for comparison with theoretical efforts; it is non-invasive, non-destructive and highly surface-sensitive. More importantly, it has a special sensitivity to hydrogen atoms, such as in methanol, and can be applied at the technologically relevant elevated temperatures. Although primarily an experimental project, there is opportunity for substantial computational modelling, and interaction with a variety of international collaborators.
Hydrogen dynamics on surfaces (Dr J Ellis) (†)
Hydrogen is becoming increasingly important in the modern world, from fuel cells to energy storage and even material degradation. However, the fundamental steps relating to its nanoscale motion are still not well understood – even the relationship between classical hopping and quantum tunnelling between different surface sites cannot easily be predicted. One of the major challenges in this field has been to obtain reliable experimental data on nanoscale surface transport, which can be used to drive further development of theory.
The aim of this project will be to experimentally study the transition from classical to quantum H motion on metal surfaces, using helium spin-echo spectroscopy (HeSE). HeSE is a unique experimental approach pioneered in the SMF group in Cambridge, which provides unprecedented access to nanoscale dynamics data. There will be opportunities to link the project with theory, to model the experimental data, depending on individual interests. Some collaboration with national and international collaborators (both experimentalists and theorists) is likely.
Dynamic processes in organic monolayers for organic electronics (Dr J Ellis) (†)
Organic electronics are a major research area of global interest, as a technology for low cost devices and, for example, large scale solar cells. The performance of such devices is controlled by the quality of preparation of molecular thin films and heterostructures. Since top-down structuring methods like lithography cannot be applied to van der Waals bound materials, surface diffusion becomes a structure determining factor that requires microscopic understanding.
The aim of this project will be to study the dynamics of species relevant to the organic electronics industry, including pentacene and fluorinated variants thereof, which enable the level of conjugation to be tuned. The project will include organic monolayer optimisation, dynamics data collection, and analysis. There will be opportunity to combine experiments with extensive molecular dynamics simulations, to further interpret the experiments, depending on individual interests. The project will involve collaboration with researchers in Germany.
Contrast mechanisms in neutral helium atom microscopy (Dr AP Jardine) (†)
We have recently developed a prototype helium atom microscope, which will enable nanoscale imaging without the possibility of sample damage (one of the major concerns with electron microscopy). The apparatus is currently undergoing a series of substantial improvements, to form a ‘second generation’ instrument, which we envisage could lead to an entirely new branch of microscopy.
Recent experiments carried out with collaborators have demonstrated unexpected and exciting forms of chemical contrast. The aim of this project is to study the range of possible contrast mechanisms, and perform experiments and simulations to understand the mechanisms at a quantitative level. It will involve helium microscopy experiments, as well as more conventional helium atom scattering studies, using a range of instruments available within the group. It will suit a keen experimental physicist who is prepared to get their hands dirty in the lab, and will benefit from ongoing collaborations with European and Australian physicists.
Nanoscale control of single crystal diamond mechanics (Dr AP Jardine) (*)
Diamond is an immensely important material both from a fundamental perspective, and in applications as diverse as quantum-computer development and highly optimised mechanical tooling. Many diamond properties are closely related to the defect structure within the material (e.g. carbon vacancies, impurities). Mechanically, the strength and toughness of diamond are both closely linked to the atomic scale defect-structure, but are vital to optimising its use in tooling.
Techniques are available to modify diamond on the nanoscale, and the overall aim of this project is to improve our understanding of the relationship between nanostructure and macroscopic mechanical properties. It will involve characterisation of nanoscale properties, performing experiments to study macroscopic mechanical characteristics and running computer simulations to examine the structure of defects, and to bridge the gap between nano- and macro- regimes. The project will form a collaboration with a major industrial partner, and the candidate will benefit from the opportunity to work directly with them for a period of time.
Reaction in energetic materials (Dr AP Jardine) (*)
Understanding the fundamental nature of reaction in energetic materials (explosives, pyrotechnics, etc.) is a substantial experimental and theoretical challenge. Despite having been studied for many decades, the process is still not well understood. The aim of this project is to develop new high-speed, microscale experimental techniques, with which to study small scale reaction. In particular, we wish to understand the nature of the reaction zone, and its dependence on material parameters. It will involve use of a wide range of fast dynamic experimental techniques and diagnostic approaches, including high speed photography and laser interferometry. There is likely scope to integrate an element of numerical modelling, depending on individual interests. It will involve close liaison with a longstanding industrial partner.
Ultra-fast Temperature Sensors for Studying Shocked Systems (Dr DM Williamson) (†)
Accurate temperature measurement during high speed events remains a consistent problem in shock-physics. Existing transducers are rate limited by their thermal mass, whereas standard optical techniques can only be applied under limited conditions (usually very high temperatures). In this project, we will focus on developing new techniques for ultra-fast temperature measurement. These will include modelling, fabrication and testing of nanometre-scale thermistor based instrumentation and fast response infra-red pyrometry. The techniques will be applied to study shock temperatures in polymeric and liquid systems, which are of increasing industrial importance.
Adhesion and damage in complex polymer composites (Dr DM Williamson) (*)
Composite materials are of great importance in the everyday world. Their fundamentally inhomogeneous nature means composites can exhibit complex forms of behaviour, relating to characteristics of the binder, filler and the nature of the interaction between them.
This project will focus on understanding energetic composite materials, which consist of an energetic species (e.g. an explosive or a propellant) held in a binder. The aim will be to study the fundamental nature of the surface interactions, and relate these characteristics back to the mechanical properties of the composite. Quantitatively understanding the complete system is a substantial challenge, but recent research within the group has demonstrated that a combination of physically based analytic models, supplemented by numerical simulations, provide a viable approach. The project will include experimental characterization using a range of established structural and dynamic techniques, supplemented by various forms of modelling and analysis. It will involve working closely with a major industrial sponsor, as well as other UK based numerical modelling groups.
Novel energetic materials based on intermetallic reactions (Dr CH Braithwaite) (†)
The ability of certain metallic species to react together exothermically and produce an intermetallic compound has led to a number of industrial products which utilise this energy (examples include in-situ welding applications and oil well perforators). Since the unreacted materials are also metallic, it has been suggested that structural components could be manufactured. However, the parameter space associated with these reactions is large, and would benefit from a systematic approach being taken to understanding the behaviour.
The project aims to draw on experience that the group has in this area, to understand the basic physical underpinnings of intermetallic reactions. These include ease of reaction, mechanical strength, and the effect that manufactured microstructure has on these properties. Ultimately the relevance of these materials is heavily correlated to the ability to control and tailor their properties. A wide range of equipment and techniques are available to use on this project, having been developed over the course of prior research.
Effect of microstructure on the dynamic response of geological materials (Dr C. Braithwaite) (†)
The dynamic mechanical response of geological materials is of great importance, both industrially and scientifically, with applications ranging from seismology and planetary impact, to oil exploration and mining. The materials themselves are often complex and polycrystalline with a variety of constituent minerals and wide range of inherent length scales. While significant research has been conducted in the field, currently there is a lack of data examining the effect that the microstructure plays in determining strength parameters.
This project aims to use a variety of existing high strain rate experimental equipment to examine the response of geological materials. Novel methodologies and diagnostics will need to be developed to monitor grain level behaviour and relate this to macroscale properties. Interaction with computational modelling will also be sought, to enhance the understanding of the experimental results obtained. The research group has substantial experience in this area and maintains a variety of relevant industrial contacts.
(†) – Project to be funded through EPSRC award scheme, or other awards.
(*) – Project to be funded directly, through dedicated project based funding.