Free radicals, molecules with one or more unpaired electrons, are highly chemically reactive. This high reactivity means that free radicals exert a major influence on the chemistry of any environment in which they are formed, even though they are often not the most abundant species. For example, it is free radical chemistry that controls important atmospheric phenomena such as the ozone hole and the formation of photochemical smog. The interactions of free radicals with surfaces are thought to be vitally important in controlling the chemistry of formation of thin-films from electrical discharges, so called plasma-assisted deposition. Such thin-films have enormous technological importance in fields such as integrated circuits and solar cells. However, the details of the interactions of the radicals with the surfaces in these film formation processes are not well understood. The major hurdle to investigating this surface chemistry of free radicals is that, currently, there is no general technique available to dose a surface with only the free radical of interest, for example CH. Current radical sources generate the radicals from a precursor gas (e.g. CH from C2H2) and the precursor gas molecules always outnumber the radicals. Thus if a surface was dosed from a conventional radical source, the precursor molecules would be the dominant species on the surface, making it almost impossible to study the interactions of the radical with the surface using standard surface science techniques. In this application, we propose the development of a new source of free radicals which will generate "clean" beams of the radical species, uncontaminated by the precursor molecule. The source will work by generating negative ions (e.g. CH-), which can be mass selected to form a clean beam. The radicals are then generated from the negative ions by using a laser beam to knock off the electron. This photo-detachment of negative ions will yield a clean beam of the radical species of interest. Calculations given in the proposal show that a practical flux of free radicals can be generated by this methodology. The clean beams of free radicals can then be used to dose the surface with the radical species, and the surface can be studied using the standard techniques of surface science to reveal the details of the radicals sticking and surface chemistry. We propose to develop the source and then use it to study the radical-surface interactions involved in three technologically important film deposition processes. The chemistry revealed by our investigations will dramatically improve our understanding of what is going on in these industrially relevant surface reactions and allow us to optimize and refine these deposition processes in the light of the chemistry that is occurring.

The so-called MAX phases comprise three elements formed into a compound. M is one of the early transition metals (Sc, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta), A is usually one of the group III A or IV A elements (Al, Si, P, S, Ga, Ge, As, Cd, In, Sn, Tl, Pb) but can also include Cd, P, S or As and X is either C or N which adds to the previously selected two elements. Their general form is Mn+1AXn where n is 1,2 or 3 and depends on the different stacking sequence of the MX block between the A-element layers. They were initially discovered in the 1960's by Nowotny et al who studied their structure. Engineering properties have been neglected until recently when it was found, by Barsoum and his colleagues, that one of these highly ductile materials (Ti3SiC2) was thermal shock resistant and oxidation resistant even at temperatures in excess of 1000oC . Thus these materials have ceramics properties yet are easy to machine.The potential application of such coatings is wide-ranging; they can be applied to cutting tools, end mills, machine components operating at high temperature, turbine blades and pipelines carrying high temperature fluids. Their composition and layered structure makes them useful for corrosion- and radiation-resistant applications with possible application as cladding layers in the nuclear industry.Conventionally the materials have been synthesised from the bulk at temperatures about 1400oC but thin film Ti3SiC2 has been formed at 1200oC by Chemical Vapour Deposition (CVD) and this compound and other phases can be formed at 900-1000oC on a suitable substrate using magnetron sputtering. For an economically viable industrial process however the process temperature needs to be reduced. Many substrates are not stable at high temperatures, for example steel, containing as low as 0.25% C, undergoes a phase transition at 723oC.The main thrust of this proposal is to develop techniques which will produce thin film MAX phases based on Ti-Si-C and Ti-Al-N at temperatures below 700oC.There are 2 novel approaches to be explored: sequential deposition of the layer components and addition of energy in the form of energetic particle collisions at the growing film surface. The sequential deposition will be achieved by switching source targets using sputtering methods, or, by pulsing different precursor gases in the CVD process. There are also concerns to be addressed in terms of deposition conditions, impurities can prevent correct nucleation of the MAX phases, single crystal substrates may be needed and a seeding layer could be required. Having formed the thin MAX phase layers they will be analysed for their correct structural properties using high resolution microscopy and for mechanical properties by measuring hardness and friction. Thermal stability will be judged from thermal cycling experiments. The coatings have high industrial interest and Teer Coatings Ltd and Applied Multilayers Ltd are supporting this programme.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

The aim of the project is to develop a batch processing route for bulk (RE)BCO high temperature superconductors utilizing two improvements that significantly advance the prospects for commercialization. The first improvement is that of incorporating a new phase, which improves the critical current densities and trapped fields. The second improvement is a seeding technique that simplifies the batch processing of large single grains. Both were developed under EPSRC-funded projects and have been patented. A recent independent market survey, commissioned by the University of Cambridge, has recommended focus on two applications which would make use of the higher field gradients provided by bulk (RE)BCO superconductors, compared with permanent magnets. The project will move fabrication from the current small-scale, highly supervised process to batch production by using a Taguchi fraction factorial approach. The business aim is to provide bulk (RE)BCO to equipment manufacturers. Products arising from the project will be incorporated into complete systems, including cryogenics, for benchmarking against permanent magnet systems by industrial partners.

The market for photovoltaic (PV) solar modules is experiencing astonishing growth due to increasing energy demand, security of supply issues, increasing cost of fossil fuels and concerns over global warming. The world market for photovoltaics grew by 139% to 21GW in 2010. Although this extraordinary pace of growth is unlikely to be maintained in the short term it will advance rapidly again at the point where grid parity is achieved. It is important that the UK retains a strong research presence in this important technology. It is proposed that the SUPERSOLAR Hub of Universities be set up to co-ordinate research activities, establish a network of academic and industrial researchers, conduct cross-technology research and provide a focus for international co-operation. SUPERSOLAR is led by CREST at Loughborough University and supported by the Universities of Bath, Liverpool, Oxford, Sheffield and Southampton. This group is active in all of the PV technologies including new materials, thin film chalcopyrite, c-Si, thin film a-Si, dye sensitised solar cells, organic PV, concentrator PV, PV systems performance and testing. SUPERSOLAR will set up a solar cell efficiency measurement facility for the benefit of the PV community in the UK. The consortium contains a deliberate balance of expertise, with no bias towards any one technology.