Magnetic Resonance Imaging (MRI) allows us to image the inside of the human body non-invasively. Pioneered in the brain this technique has become invaluable over the last 5-10 years for imaging the heart in the clinic. MRI scanners operate at a magnetic field strength of 1.5 Tesla. Increasing the magnetic field strength can provide higher image quality and we have pioneered the use of 3 Tesla scanners. The highest commercially available human field strength is 7 Tesla, which is our next step. Imaging at higher field strength results in more signal, and thus, the images are obtained quicker, or with higher spatial resolution. The areas that we will develop are those that are limited by low SNR (signal-to-noise ratio) at 1.5 and 3 Tesla. These include imaging the coronary arteries and the energy-rich metabolites in the human heart. Coronary artery imaging is important as these vessels are critical to supplying blood to the heart (blockages cause ?heart attack?). The higher SNR of 7T will allow us to image the blood and walls of these vessels at higher resolution than has previously been possible with MRI enabling us to visualise small plaques and subtle damage. The metabolic condition of the heart is another important area of research where we in Oxford are world leaders. A technique called MRS (magnetic resonance spectroscopy) shows the biochemistry of the heart. Levels of phosphocreatine and adenosine triphosphate, which are essential energy-providing metabolites, can give an indication of damage even before functional changes become apparent. At 7T, the higher spatial resolution enables the MRS examination of small regions in the heart, equivalent to those presently required in clinical examination (this is impossible at lower field). Additional projects will build on these methods to look at oxygen supply, the degree of fibrous scar tissue, and the blood supply from small vessels in the heart. Clinically these developments have the potential to transform MR imaging of cardiac metabolism, oxygenation, and coronary plaque biology from a niche research tool into a mainstream diagnostic measure that can treat the patient as an individual, enabling doctors to monitor the progress of a disease or the response to therapy over time. These techniques would contribute significantly to improving cardiovascular health and to relieving the burden of cardiovascular disease. Our plans are highly novel, and we would be the first site in the UK, and probably in Europe, developing cardiac MR at 7T.
The research project and department will be chosen at the end of the first year of study and this record will be updated shortly after.
Hybrid halide perovskites have attracted huge attention ever since it was shown that they could be used in highly efficient photovoltaic devices produced via low-cost deposition methods. Their exceptional attributes, including high carrier mobility, an adjustable spectral absorption range, long diffusion lengths, and the simplicity and affordability of fabrication make them one of the most exceptional and market-competitive optoelectronic materials for applications in photovoltaic, light emitting diodes, photodetectors, lasers and more. Despite the phenomenal properties of hybrid perovskites, several crucial issues still need to be tackled before their industrial-scale, including toxicity, instability and an anomalous hysteresis in the current-voltage curves. Whereas an ever growing number of studies focus on improving optoelectronic properties, there is still an urgent need for a detailed understanding of these materials at a more basic level. For example, the nature (organic or inorganic) and ionic size of the perovskite A-site cation leads to strikingly different trends in the properties of these materials. This project is framed in this context, and its principle goal consists in understanding the intrinsic properties of halide perovskites and how they affect the devices performances. Since the project targets intrinsic properties, an early goal will be to grow and characterize high-quality polycrystalline and single-crystal samples of hybrid or inorganic materials, and to understand the mechanisms that lead to good materials stability. As an example, very recently the addition of a small percentage of caesium and bromine in the FAPbI3 compound allowed a more stable perovskite structure to be obtained. A second early challenge will be to perfect the growth of single crystals (presently just in the early stages), since these samples are highly desirable to investigate intrinsic properties of perovskites, due to their low trap density and absence of grain boundaries. Moreover, some of the most incisive techniques exploiting neutron and synchrotron sources require single crystals. We will also explore the possibility of growing entirely new hybrid or inorganic materials for optoelectronic applications, by combining the insight provided by Density Functional Theory (in collaboration with Prof. F. Giustino's group) with synthesis and characterisation. The overarching goal of the experiments we will perform on these samples is to understand structure-property relationships in both hybrid and fully inorganic systems over the entire phase diagrams (temperature, composition, pressure), and to guide their rational design and fine tuning of their optoelectronic properties. In particular, for hybrid materials, we will investigate the interaction between organic and inorganic species to better use the advantages of both components. With this intent, we will deploy a panoply of characterisation techniques on both polycrystalline samples and single crystals, including: neutron and x-ray diffraction (lab and synchrotron), ferroelectricity and dielectric spectroscopy measurements, coherent and incoherent inelastic neutron scattering, and X-ray spectroscopy (XAS, EXAFS), all in combination with the classic light spectroscopy techniques that are widely employed to study photo-carriers in these materials. The direct impact will be to deliver efficient materials for the device architecture and to gain a deeper understanding of the relationship between the material properties and the devices. The academic impact will be a number of high profile scientific papers. This research falls within the EPSRCS research areas of Materials for Energy Applications, and Solar Technologies.
Particle physics seeks to understand the Universe and its evolution in terms of the interplay of elementary particles (the quarks and leptons) the fundamental forces (the strong, electromagnetic, and weak forces and gravity) and the force-particles that mediate them (photons, W/Z, gluons and gravitons). The last thirty years has seen the development of a robust and extremely successful theoretical framework, known as the Standard Model, in which almost all of the available particle-physics data can be explained. However, whilst this is a beautiful theory, the model is incomplete since it doesn't completely explain the world that we see around us. Oxford's research programme will advance significantly our understanding of whatever "new-physics" theory will emerge to replace the Standard Model, and will guide the theoretical work to develop it. The Large Hadron Collider (LHC) is now running at the energy frontier of high-energy physics, and reproduces the conditions within milliseconds of the Big Bang. Oxford plays a major role in the detector operation and the extraction of physics results from both the ATLAS and LHCb experiments, including studies of the Higgs particle, particles having "supersymmetry" (SUSY), and the origin of the matter-antimatter asymmetry in the Universe ("CP-violation"). Over the next decade, the LHC will upgrade to higher energy and intensity, and so detector improvements are being prepared for both ATLAS and LHCb. The upgraded detectors will take particle physics to an unprecedented limit of sensitivity for the inevitable new-physics observations. Throughout our work we are enabling powerful computing resources and analysis tools that are necessary for the extraction of vast volumes of data. We participate in high-precision experiments that are complementary to the large experiments at the LHC. The EDELWEISS and LUX-ZEPLIN experiments are exploring some of the most important questions in particle physics and cosmology; in particular the direct search for dark matter, a candidate being the lightest SUSY particle. Similarly the nEDM experiment will measure the neutron electric dipole moment down to unprecedented precision, and which will also complement measurements of CP-violation from the LHCb experiment. Through the T2K experiment in Japan and future experiments such as LBNE, Oxford physicists aim for a better understanding the elusive neutrino, and in particular its "oscillation" from one flavour to another. The SNO+ experiment will measure other fundamental properties of the neutrino, such as whether or not it is its own antiparticle. Throughout our research, Oxford will continue to develop and enhance our capabilities in mechanical and electronic design so that we will retain the ability to construct the most sophisticated apparatus of whatever size may be required for our physics objectives.
This DPhil project focuses on predicting and understanding excited state properties of semiconductions and insulators from the application first principles computational modelling methods. The aim is to use and develop upon state-of-the-art methods including but not limited to density functional (perturbation) theory and Green's function based many-body perturbation theory to understand how light interacts with matter in complex functional semiconductors and insulators, under 'real' conditions. This will likely require extending existing theoretical frameworks to include complex interactions such as electron-hole and electron-phonon interactions. This will lead to important developments of predictive methods and frameworks for the physics of electronic and optical excitations in semiconductors and insulators where the state-of-the-art has proved insufficient to accurately describe phenomena. Extending this capability will have an important impact not only to theoretical development of new methods, but it will also assist experimental spectroscopic measurements to better understand excited state properties of materials from an atomistic perspective. Aims and objectives; Use and develop upon state-of-the-art methods including but not limited to density functional (perturbation) theory and Green's function based many-body perturbation theory to understand how light interacts with matter in complex functional semiconductors and insulators Novelty of the research methodology; We will use state of the art methodology including but not limited to density functional theory and green's function based many-body perturbation theory, and we will develop new methods and frameworks as needed to more accurately describe excited state phenomena. Alignment to EPSRC's strategies and research areas (which EPSRC research area the project relates to). Please add 'This project falls within the EPSRC XXXX research area' where XXXX is one of the themes or research areas listed on this website https://www.epsrc.ac.uk/research/ourportfolio/themes/ This project falls within EPSRC Physical Sciences Theme Any companies or collaborators involved. At this stage we expect that part of this project will include a collaboration with the group of Prof. Jeff Neaton at the Lawrence Berkeley National Lab and UC Berkeley in the USA.