If you are interested in applying to any of the project below, please do so here
These projects are available to Departmental/DTP and any other funding source.
Biomaterials and Tissue Engineering
Development for new biomaterials for biosensing
Supervisor: Prof Molly Stevens
Disease states, such as cancer, malaria, heart failure and tuberculosis, introduce biomolecular changes in signatures of proteins, enzymes or nucleic acid make-ups that represent targets for diagnostic tests, yet currently used tests suffer from inaccuracy, insensitivity, difficulties with implementation or high costs. Innovative nanomaterial-based assays represent cost-amenable approaches that could be used as technological platforms capable of ultrasensitive detection of disease biomarkers giving easily interpretable outputs (e.g. colour changes), which would transform the field of biosensing. The aim of this project is to develop new nanomaterial-based arrays capable of detecting biomarkers for cancer and infectious diseases at ultralow concentrations. The nanomaterials will be designed and optimised according to the concentrations of relevant biomarkers and cost-amenability of the nanomaterial assay. The physical properties of the assay will need to be fully characterised to understand the effects of agglomeration and influence of surrounding protein moieties.
Development of new biomaterials for regenerative medicine
Supervisor: Prof Molly Stevens
Despite the number of incredible advances made in tissue engineering during the past decades, there remains an enormous demand for innovative materials that can be used as regenerative scaffolds. Polymer-based materials have provided fundamental knowledge involving the effects of specific physical and chemical cues on cell behaviour, yet still only a select few designs are successful in translation. Novel cell-instructive polymer-based constructs need to be designed and tested for their clinical suitability in terms of how they can mimic the properties of native tissues, while their mechanical properties and tailored biofunctionalisation will need to be elucidated to yield controlled bioactivity. The aim of this project is to understand how these materials can be designed and optimised for clinical translation by exploiting the knowledge gained at the cell-material interface. This project will focus on the synthesis of polymer-based materials and the understanding of the physical and chemical properties as elucidated using state of the art materials-based characterisation techniques. The emphasis of the material characterisation will lie on the cell-material interface and how the engineered biomaterials influence this region. This project will involve advanced synthetic techniques, complete material characterisation as well as biological tests.
Inorganic theranostic nanoparticles for Tuberculous Meningitis
Tuberculous meningitis (TBM) is the most severe form of tuberculosis infection with very high mortality and accounts for 2-5% of all tuberculosis (TB) cases among children and HIV-positive adults, causing permanent neurological consequences and disability. There is an urgent clinical need to develop vehicles to deliver antimicrobials/anti-inflammatories directly inside the brain to treat and diagnose early stage TBM. The research will focus on:
- (i) synthesis and physicochemical characterisation of spherical and flower shape of mesoporous silica nanoparticles (NPs) with controlled size (<100 nm) containing first line antibiotics for optimal BBB crossing.
- (ii) Incorporation of therapeutic ions (Ce as antioxidant and Fe for MRI imaging).
- (iii) Decoration of NPs with pH responsive polymer which allows NPs to be absorbed and pass into the blood stream.
- (IV) In vitro testing of NPs transcytosis formulation.
Nanoscale 3D-printing of hydrogel biomaterials for tissue culture
Supervisor: Dr Iain Dunlop
Cells in vivo receive from their environment signals of many types, reflecting the biochemistry, mechanics, topography and spatial structure of their microenvironments. Artificial biomaterials for tissue engineering and culture need to mimic these in vivo microenvironments. Polymer hydrogels have proven fruitful as materials that simultaneously control mechanical properties and biochemistry. However, there is a need to deliver equivalent control of spatial structure. Importantly this control must extend to the sub-micron lengthscales that embody key sub-cellular structures in vivo. The project will develop advanced 3D-printing methods to structure biomaterial hydrogels on the sub-micron scale with control of mechanical properties and biochemistry. This will exploit very recent developments in optical instrumentation that have demonstrated Direct Laser Writing as a viable 3D-printing technology at sub-micron lengthscales. This technology is effective in 3D-printing photonic nanomaterials, but only very limited biomaterials work has been carried out. The student will develop new hydrogel biomaterials and 3D-printing protocols to create novel spatially-structured tissue culture. The project will suit a student with a background in Materials, Chemistry, Chemical Engineering or Bioengineering.
New nanomedicines for cancer immunotherapy
Supervisor: Dr Iain Dunlop
The next generation of cancer treatments will be dominated by immunotherapies that direct the patient immune system against the disease. New approaches under development include a vast range of single molecule biologic drugs. However the architecture of the immune system itself shows that immune cells are typically stimulated not by individual molecules but rather by supramolecular clusters of the order of 100 nm in size. Our lab is exploiting this insight by developing new nanoparticle-based reagents that directly mimic the natural nanostructures that stimulate immune cells in vivo. These have potential to be applied both for direct injection into patients and also for stimulating immune cell cultures to enable genetically-modified cell therapies such as Kymriah (tisagenleleucel), recently licensed by the UK NHS. The student will contribute to this work, developing new nanoreagents and evaluating their performance in immune cell stimulation. The project will suit a student with a high level of motivation for interdisciplinary work, with a background in Materials, Chemistry, Chemical Engineering, Biochemistry or Bioengineering. Key references from our lab: Nano Lett. 18, 3282 (2018); Integr. Biol. 9, 211 (2017); Nano Lett. 13, 5608 (2013).
Ceramics and Glasses
Cation diffusion at the La4-xPrxNi3O10/La1-xSrxGa1-yMgyO3-d electrode electrolyte interface: an atomic scale investigation
Supervisor: Prof Stephen Skinner
Development of the La4-xPrxNi3O10 (LPN)/La1-xSrxGa1-yMgyO3-d (LSGM) electrode structure has highlighted the requirement for a porous LSGM interlayer between the LPN electrode and the LSGM electrolyte in solid oxide cells (SOC). Without this layer the performance of the cell is significantly worse. What is the function of the layer? Does this act as a barrier to cation diffusion, or is this area the effective electrochemically active site? Are the interfaces between LPN and porous LSGM acting as triple phase reaction sites? To address these questions we will investigate the interface between these phases in well-defined samples using a combination of analytical techniques including transmission electron microscopy (TEM) atom probe tomography and secondary ion mass spectrometry. TEM will provide detailed atomic scale information regarding the composition of the interfaces between grains that can then be correlated with the electrochemical performance of the electrode.
Ceramic property variation as a function of water corrosion at interfaces
Supervisors: Dr Katharina Marquardt and Prof David Dobson
Understanding of the impact of interfaces is critical to enhance their properties for the development of future industrial materials. Such materials find application in for example biomedical devices or corrosion resistant surface treatment of cooling systems.
Here we will focus on the investigations of ceramics that are exposed to high-temperature and supercritical water. Understanding the reaction mechanism at interfaces and the character variations of interfaces as a function of exposure to H2O is at the heart of the study. The results will have double significance as they are additionally applicable to reactions and transport processes at conditions of the Earths lower crustal zone and thus an interest in Geology might be satisfied too.
The student will work in a team with various expertise and a spirit of working together. While we have common overarching goals, we work on independent project. In this project the student’s role will be to synthesise, react and characterize the material using mechanical testing, novel scanning electron microscopy techniques as developed for electron backscatter diffraction (EBSD) and transmission Kikuchi diffraction (TKD). Additionally, transmission electron microscopy (TEM) and infrared spectroscopy will be employed to study the interfacial structure and composition of the ceramics at the nm-scale. This work is done in a team with various expertise and a spirit of working together.
The candidate will learn during her/his stay ceramic processing, sol-gel sintering techniques, as well as structural and mechanical characterization techniques. He/she will develop strong skills in the scientific approach, problem solving, and the communication of scientific results and in collaborative working in an international team.
Probing the proton mobility in La(Nb,W)O4+d ceramic electrolytes
Supervisor: Prof Stephen Skinner
La(Nb,W)O4+d ceramics have been previously identified as excellent fast oxide ion conductors, with oxygen tracer diffusion coefficients, D*, of the same order of magnitude as leading solid oxide fuel cell electrolytes such as yttria stabilised zirconia (YSZ). The parent composition, LaNbO4 substituted with low levels of Ca has been proven as a proton conducting electrolyte, offering possibilities of lower the operating temperature of fuel cells, or the clean production of dry H2 through electrolysis. In this project the potential of the W and/or Mo substituted phases as proton conductors will be investigated. Prepared ceramics will be exposed to labelled gases including D2O and H218O and their total conductivity investigated experimentally. Using a combination of experiment and simulation techniques we will determine the mechanism by which both the protons and oxide ions move. The temperature and pO2 dependence of the transport phenomena will be evaluated and each of the materials tested in an electrolyser application.
Understanding Li-ion diffusion in battery systems
Supervisor: Dr Ainara Aguadero
The transition to an electricity-based transport network requires improvement in the lifetime and performance of state-of-the-art Li batteries. This is directly correlated to the Li ion dynamics (exchange coefficient and diffusion) within the electrodes, electrolytes and their interfaces. Most importantly, these Li-ion dynamics are heavily dependent on the state of charge, working conditions (Temperature, bias) and degradation processes (cation interfusion, phase transition and parasitic redox processes) taking place during battery cycling. At the moment there is not an experimental technique able to quantify the correlation between degradation and Li mobility in materials.
This project aims to establish a reliable protocol that can universally quantify Li kinetics in battery materials by using 6Li-labelling coupled to surface analysis techniques.
The development of this technique, will allow us to correlate different states of charge of the battery, degradation processes and battery performance to understand where the main limiting factors are and how to control them. The full fundamental study of these complex systems is not easy with state of the art characterisation techniques due to problems with combined sensitivity, resolution and in situ analysis. However, we have very recently been awarded with an EPSRC strategic equipment grant to develop a unique combination of PFIB and SIMS (Hi5) that provides a step change in performance of state-of-the-art instrumentation in terms of resolution, sensitivity and in situ/in operando applicability. The combination of this new capability with isotopic labelling, electrochemical analysis and simulation studies brings a unique opportunity to successfully develop this exciting project.
ZrO2-corrosion-layers and their grain boundary network: impact on cladding quality
Zr-alloys are used for nuclear fuel cladding in water-cooled reactors. These alloys corrode in contact with the hot water and steam (Féron 2012). A zirconium oxide layer forms at the beginning of the oxidation process. This layer causes a reduction in the oxidation rate. The migration of charged species in the oxide layer is largely controlled by the microstructure (Garner et al. 2015, 2017) and grain boundary network of this oxide layer (Gertsman et al. 1997).
Initially a non-equilibrium tetragonal phase growth close to the metal-oxide interface. It can form due to compressive stress present at the metal-oxide interface. However, as the layer gains thickness the reactive interface between metal and oxide is further from the surface and the compressive stress decreases. Eventually the stress is insufficient to stabilise the tetragonal phase and a transformation from tetragonal to monoclinic ZrO2 happens. Monoclinic ZrO2 is the stable phase at atmospheric pressure and temperature below 1500 K.
Here we aim at characterizing the behaviour of different grain boundary networks using state-of-the-art meso- to nano-scale characterisation techniques including transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) techniques (e.g. Britton and Wilkinson 2011; Marquardt et al. 2017). We will experimentally alter Zr-alloys in chemically varrying environments and investigate how this affects the formation and microstructural properties of the resulting Zr-oxide layers. Eventually the experimental data will be used to explore the microstructural properties using different modelling approaches.
2- Evaluation of methods to characterize SO2/SO3 ratio to prevent corrosion of nickel superalloys for engineering applications
H2S, present in the earth crust, is released during volcanic eruptions. In the atmosphere, it oxidizes first as SO2 and (probably much) later as SO3. While SO2 is relatively benign, SO3 ingested with the air reacts strongly with the gas turbine blades causing degradation. In addition, some gas turbines also operate with untreated raw gas containing a significant amount of H2S. It is thought that in both situation residence time, sealing efficiency of the wheel space are playing a major role on the conversion of SO2 to SO3. However, no instrumentation method can verify this assumption (and only imprecise thermo chemistry models are used). This project will develop characterisation methods to help explore the parameters affecting the conversion. This measurement method will be developed on a dedicated rig by varying the temperature, moisture and type of catalyst used. The findings will then be fed into a model which will be implemented for lifetime prediction of nickel-superalloys in service in industrial gas turbines.
Dr Stella Pedrazzini, Dr Ifan Stephens. Industrial collaborator: Solar Turbines.
3- Corrosion of 3D printed titanium lattices under simulated body fluids for biomedical applications
In the last decade, a new revolution in engineered materials has emerged: mechanical metamaterials (MM). These micro-architectured, 3D printed materials are pushing the limits of traditional materials by controlling the mesostructure with high precision, giving rise to extreme or even unseen properties. Advances in 3D printing are attracting the attention of biomechanical companies, to manufacture more osseo-integrative and fatigue resistant prostheses. This project will analyse some 3D printed titanium-based structures and corrosion-fatigue test them under simulated body fluids (mixtures of water, oils and salts) at different temperatures and under different loading conditions. Extensive mechanical testing and microstructural characterisation will be employed. Crack propagation will be monitored through in-situ synchrotron studies.
Atomic scale modelling of chemical attack at crack tips in advanced zirconium alloys
Superviosr: Dr Mark Wenman
In today’s world of renewable energy nuclear power needs to be more than just base load and needs to be able to manoeuvre in power to follow the grid requirements removing the need to do this through gas fired stations and therefore reducing CO2 and making nuclear power more flexible. However, nuclear fuel is not designed to do this and many restrictions are in place for changes in power level. The most stringent of these restrictions is to prevent the interaction of nuclear fuel pellets with the zirconium metal fuel tubes that enclose them. However, during power changes nuclear fuel produces significant amounts of chemically reactive species, such as iodine, that can attack the metal leading to cracking. This is fairly well characterised in old alloys through lots of operational experience but for new alloys where tests are scarce and expensive no such data exists. This project aims to understand the chemistry of iodine attach mechanisms at crack tips in zirconium metal in the presence of oxygen to inform industry. To do this quantum mechanics (QM) is required but using QM alone limits system studies to a few hundred atoms only – not enough to simulate cracks. Here, the approach is to combine QM within an empirical potential scheme to model hundreds of thousands of atoms but retaining the important quantum-chemistry at the crack tip. As this project has a strong industry drive it is expected to involve meetings with Westinghouse and nuclear operators as well as participation in a broader multi-university programme on zirconium called MIDAS.
Controlling intermetallic compounds in light alloy castings
Supervisor: Dr Chris Gourlay
Al and Mg castings have great potential to simultaneously deliver lightweighting and cost savings in the aerospace and automotive sectors. However, to be used more widely in these applications, damaging intermetallic compounds (IMCs) such as Al13Fe4 and Al5FeSi must be understood and controlled during solidification to ensure the adequate ductility, fatigue performance and corrosion resistance of castings. The research will focus on two areas: (i) the development of impurity-tolerant recycled Al- and Mg-alloys for automotive applications, and (ii) pushing the limits of high-purity Al- and Mg-alloy aerospace castings. The project will build the understanding of the nucleation and growth of selected IMCs during solidification, and use this to control the IMC phases that form, their size, and their morphology. The approach will combine solidification processing, a variety of characterisation techniques and thermodynamic modelling.
CuZnAl elasto- and magnetocalorics for heating and refrigeration
The next big challenge for UK decarbonisation is heating and cooling, which account for ~25% of global electricity demand and ~25% of UK CO2 emissions from the use of natural gas in heating. Heat pumps, as used in refrigeration, are a feasible way to electrify and then decarbonise heating and cooling, and are already mandated in Holland as it looks towards the decommissioning of the domestic gas grid. Step-change improvements in heat pump efficiency are available from the substitution of the vapour compression cycle with cycles based on caloric materials. In this project we will pursue the development of CuZnAl elastocalorics for this application, focussing on improving their cyclic lives from ~105 cycles presenting to the 109 cycles required. We will also pursue options for coupling these with magnetocalorics to produce multi-caloric high surface area regenerator structures, e.g. through electrodeposition or through powder techniques such as metal injection moulding. Finally, we will also examine the performance and degradation of such materials in demonstrator regenerators, with a particular focus on the interaction with the heat transfer medium (i.e. water). Techniques used will include 0.5kg-scale ingot melting and processing, , electron microscopy (incl (S)TEM, EBSD), with the potential to then use advanced characterisation techniques such as atom probe tomography and neutron and synchrotron x-ray diffraction.
Designing printable alloys by combining thermodynamics calculation and machine learning
Supervisor: Dr Minh-Son Pham
Additive manufacturing (AM) is expected to revolutionize the manufacturing industry. However, fabricating reliable and high performance metals by AM still remains one of the biggest challenges in AM of metallic alloys. Most of alloys made by AM have higher strength, but lower ductility compared to those made by other processes. One of main reasons is because existing alloys currently used in AM were initially designed for other processes (e.g., casting, rolling, etc), not for AM that induces microstructures so much different to those in other processes (ref: M.S. Pham et al. The role of side-branching in microstructure development in laser powder-bed fusion. Nature Communications 11, 749 (2020)). Therefore, there is an increasing call to design new alloys that are tailored for AM to help unlocking the full potential of additive manufacturing. In this study, the student will assess the printability of existing Ti, Ni and Fe-based alloys by evaluating their thermodynamics properties, then use a machine learning software Scikit-learn to accelerate the search and discovery of new printable alloys. The student will subsequently validate the machine learning prediction by printing selected compositions and provide feedback to improve the learning capability.
Development of ‘big data’ approaches for electron diffraction and microstructural characterisation
Supervisor: Dr Ben Britton
We will work together to develop new methods to interpret, classify, and extract information from electron diffraction patterns. These will usually employ machine learning approaches, including convolutional neural networks, adversarial machine learning, and principal component analysis to enable us to maximise the signal to noise and extra new information from crystalline materials. These approaches will be used to help understand materials used in high-value high-risk applications such as aerospace, nuclear power and oil & gas, as well as extra-terrestrial materials such as meteorites. The project will mostly be theoretical, with some hands-on electron microscopy to collect experimental data. You will work within the Experimental Micromechanical Group (www.expmicromech.com). We are particularly excited to received applications from candidates who are members of typically underrepresented groups in higher education.
Dwell fatigue in titanium alloys
Supervisors: Prof Fionn Dunne and Prof David Rugg (Rolls- Royce)
Titanium alloys are used in safety-critical jet engine components and can sometimes undergo a degradation and failure process known as cold dwell fatigue. The mechanism is interesting since it is crucially sensitive to microstructure, particularly local crystallographic orientation, and to the creep deformation which takes place even at low homologous temperatures in these alloys. We utilise crystal plasticity, discrete dislocation and molecular dynamics modelling techniques. In addition, quantitative characterisation and small-scale experimental testing with high resolution digital image correlation, high-res electron backscatter detection, and ultrasonic wave speed methods are also important. PhD projects in modelling and experimental studies (or preferably both) are available.
Mesoscale modelling of oxide growth on advanced zirconium alloys
Supervisor: Dr Mark Wenman
The life limiting factor for nuclear fuel pins is the corrosion and hydrogen uptake of the zirconium metal fuel tubes. The zirconium metal reacts with the water reactor core coolant to produce a layer of zirconium oxide with a by-product of hydrogen. The hydrogen embrittles the metal and limits its life. However, as it is produced by the corrosion process it is vital to understand what controls the rate of oxide growth. The oxide growth varies depending on the alloy and tends to show a periodic growth cycle where cycles are separated by the formation of layers of cracks in the oxide. Thus far these have been too difficult to model but here it is proposed to use a method known as peridynamics embedded in a commercial finite element code Abaqus. Peridynamics is a meshless method that can accommodate crack nucleation and growth without any prior knowledge of where they may form. The project will build micron scale models of the oxide and compare to experimental industry micrograph results. Ultimately the aim is to determine the cause of the crack formation, when they grow and how they coalesce. This project is supported by industry partners of Rolls-Royce and Wood and would be part of a much wider international collaboration on understanding zirconium corrosion called MUZIC.
Micromechanical characterisation of advanced engineering alloys
Supervisor: Dr Ben Britton
We will work together to develop new understanding of the deformation of metal alloys used in high-value high-risk applications, such as oil & gas, nuclear power, and aerospace. You will develop new methods to extract mechanical performance at the nm to mm lengthscale with in-situ methods, such as micro-pillar compression combined with high spatial resolution digital image correlation and high angular resolution electron backscatter diffraction. Together these methods will be used to understand properties such as the evolution of fatigue damage in metals and alloys, as well as providing fundamental understanding of materials to enable their sustainable use in high performance applications. You will work within the Experimental Micromechanical Group (www.expmicromech.com). We are particularly excited to received applications from candidates who are members of typically underrepresented groups in higher education.
Microstructure formation in electronic solders
Supervisor: Dr Chris Gourlay
The solidification microstructure of microelectronic solder joints plays a key role in determining the reliability of electronics. During soldering, it is common for solder balls to undercool below their liquidus temperature by tens or hundreds of Kelvin. When nucleation occurs, rapid solidification is triggered and the undercooling at the growth front decreases due to latent heat release. These phenomena lead to competition between different growth forms (dendrites, eutectic etc.) and complex microstructures form. This project will study the undercooling-microstructure relationship in 100-500 micrometre diameter solder joints using differential scanning calorimetry (DSC) and electron microscopy. The results will be used to develop microstructure selection maps that will improve the understanding of undercooling-microstructure-property relationships in Pb-free solder joints and guide new alloy development.
Modelling delayed hydride cracking and crack growth in Zr cladding
Supervisors: Prof Fionn Dunne and Mike Martin (Rolls-Royce)
We wish to develop capabilities to address the problem of delayed hydride cracking in Zr cladding for the nuclear industry. Here, the role of hydrogen and its diffusion through the Zr alloy is crucial. Diffusion rates are strongly influenced by stress and the hydrogen concentration and temperature determine saturation when hydrides potentially form. These phases may, under thermal cycling, crack and lead to subsequent fatigue crack propagation. The new project is to establish crystal plasticity coupled hydrogen diffusion models, including hydride formation and dissolution, with crack nucleation and growth such that computational predictive modelling can be developed for Zr component design for reactor cores. The project is largely theory/computationally based but there is scope for interested applicants for focused small-scale experiments with our existing kit for thermomechanical loading with specialist characterisation involving high resolution digital image correlation and high-res electron backscatter detection.
Funding Details (Home students only).:
50% funded by Rolls-Royce, incl top-up of bursary to £20k for 4 years.
50% funded by Nuclear CDT, Department or Faculty of Engineering DTA CASE conversion
Project supervisor: Dr Minh-Son Pham
We recently presented a groundbreaking research that leads to a new generation of meta-materials mimicking crystal microstructure found in high performance metallic alloys (refer to M.S. Pham et al., Damage-tolerant architected materials inspired by crystal microstructure, Nature 2019; 565:305). The design of these new meta-materials is realised by additive manufacturing via 3D printing, offering an innovative way to fuse the metals science and 3D printing to design advanced materials with desired properties. This Phd studentship will explore many more exciting opportunities offered by this approach, in particular when combining this approach with multi-functional materials to develop high strength programmable materials. The qualified candidate will use various computer software to mimic microstructure found in nature to design new meta-materials that are not only mechanical robust, but also adaptive. S/he will use advanced 3D printing and material characterisation techniques to fabricate and study the behaviour of designed materials. S/he needs to team up with other students and effectively collaborate with our key academic and industrial partners in UK, France and USA.
Taking Co/Ni superalloys into service
Supervisor: Prof David Dye and Dr Mark Hardy (Rolls-Royce)
We have been developing new polycrystalline Co/Ni-base superalloys for jet engines for a number of years and hold several patents. They have now reached a stage of maturity where applications are coming into view, with tensile, creep and oxidation behaviour that exceeds those of alloys in service in many instances. From ingot and powder route starting points, the next steps are to develop these for additive layer manufacturing, ring rolling and extruded parts. Technique opportunities include the EBSD examination of deformation substructures, (S)TEM, synchrotron x-ray and neutron diffraction, mechanical characterisation (i.e. forging, fatigue) and atom probe tomography (with Oxford or MPIE Dusseldorf).
50% funded by Rolls-Royce, incl top-up of bursary to £20k for 4 years.
50% funded by Characterisation CDT, Department or Faculty of Engineering DTA CASE conversion (Home students only).
Understanding the atomic-scale osteoinductive properties of bio-ceramics for bone regeneration
Supervisor: Dr Baptiste Gault and Prof Eduardo Saiz
Bone can self-regenerate, however, often bone regeneration is enhanced by the use of a “bone graft”. Synthetic bone grafts from calcium phosphates (CaPs) have raised interest due to their similarity to the mineral composition of bone, their abundance, and their excellent clinical performance. Most efforts to use CaP as bone substitutes have been devoted to sintered CaP such as hydroxyapatite, β-tricalcium phosphate and their composites called biphasic CaPs (BCP). Numerous studies have investigated the in vivo behavior of CaP and have revealed that HA, β-TCP and BCP are resorbed by cell-mediated acid-driven dissolution, with preferential attacks at grain boundaries that threaten the structural integrity of the ceramics. Not all grains and grain boundaries are susceptible to these attacks, or at least not at the same rate, which could be related to the specific composition of the grain boundaries. Doping was shown to lead to changes in the dissolution behaviour, but the reasons underpinning this change are still unknown. To address this significant knowledge gap, we propose a project focused on the measurement of the composition of grain boundaries at the atomic scale using atom probe tomography, combined with electron microscopy where necessary, on a series of model ceramics with controlled levels of dopants. By relating the composition of grain boundaries to their in vitro and in vivo behaviour, we hope to pave the way for designing biologically more potent ceramics, in particular ceramics with osteoinductive properties.
This project will be under the supervision of Dr Baptiste Gault and Prof. Saiz at Imperial College London and in collaboration with Dr. Marc Bohner from the RMS Foundation (https://www.rms-foundation.ch/en/staff-member/marc-bohner.html) for the synthesis and in vitro tests. Most of the work is to be conducted at the Max-Planck-Institute für Eisenforschung in Düsseldorf, Germany, where Dr Gault is based.
2D functional inks for optoelectronic applications
Supervisor: Prof Milo Shaffer
Exfoliated 2D nanomaterials offer multiple beneficial physicochemical and functional properties in a format that can be prepared as an ink and printed to form flexible electronic devices. Graphene has attracted enormous interest but lacks a straightforward band gap, meaning it can only be conveniently used as a conductive material. Other 2D materials, such as Transition Metal Dichalcogenides (TMDs), offer a well-defined band gap, suitable for transistors, photodetectors, or emitters. By preparing and combining inks based on this palette of materials, device applications can be developed. To maximise the performance, the exfoliation process must be optimised, since the TMD properties depend on the degree of exfoliation and the lateral size of the layers, as well as their inherent structure. Our commercial partners are developing a range of functional inks based on 2d materials. This project will explore the application of these inks to thin film electronics, linking the nature of the ink, through the deposition process, to transport properties and then device performance. The project will involve detailed characterisation using a range of advanced microscopy and scattering methods to determine the nature of the ink, establish protocols for patterned film (and hybrid film) deposition, and finally design/evaluate protoype devices. By iteration with the team at the company, new optimised materials will be developed, providing a rapid route to real world application.
3D printed microsupercapacitors based on 2D material inks for on-chip technologies
Supervisor: Dr Cecilia Mattevi
With a fast developing of the internet-of-things, wireless sensor networks deployed in a variety of environments for home automation, health monitoring, environmental control and industrial processes tracking are becoming a permeating technology. A necessary requirement for these small sensors and networks is energy autonomy. An energy-storage component is critical to store energy harvested from renewable sources to ensure energy supply over prolonged periods of time. Microsupercapacitors with high efficiencies over small footprint areas would benefit these applications. To date device miniaturization has been developed to achieve mainly planar-geometries. 3D printing offers the opportunity to fabricate devices with different architectures and to develop those over the vertical direction. The objective of this project is to fabricate microsupercapacitors via a 3D printing technique based on continuous extrusion of a viscoelastic ink. The materials of choice are 2D atomically thin transition metal dichalcogenides (TMDs) in their metallic polymorphism (1T/ 1T’ phases) which are promising for energy storage applications. The project will involve inks formulation, 3D printing of electrodes and current collector, detailed characterisation using advanced microscopy and tomography methods to determine the microstructure and the 3D ordering of the platelets and to design and evaluate devices. Advanced spectroscopy characterization will be also utilized to study chemical composition and crystal phase. Upon device evaluation, microstructure, design and the ink formulation will be modified to optimize energy density and power density of the microsupercapacitor.
Accelerating the development of anisotropic chalcohalides for non-toxic, stable photovoltaics
Supervisor: Dr Robert Hoye
Solar cells made from lead-halide perovskites have rapidly outperformed industry-standard silicon photovoltaics despite being made by cheaper methods. A key enabling property is the ability of the lead-halide perovskites to tolerate its most common point defects. Bismuth- and antimony-based compounds have recently been predicted to replicate the defect-tolerance of the lead-halide perovskites, but have the critical advantage of being substantially less toxic. Chalcohalides (such as BiSI and SbSI) have gained attention because these compounds have suitable band gaps for photovoltaics, are processable using simple and scalable methods, and are stable in air. However, the one-dimensional structure of these materials results in anisotropic charge-carrier diffusion lengths, which is challenging to integrate with standard vertically-structured diodes. This project will develop a Microstructured Interdigitated Back contact Solar cell (MIBS) to extract photogenerated carriers from the high-mobility lateral direction in compact c-axis oriented thin films. MIBS will comprise of alternating n- and p-type electrodes spaced 1–20 mm apart, which will be probed with photocurrent spectroscopy to measure diffusion length. This will allow the photovoltaic potential of chalcohalides to be established faster, which can accelerate the optimisation of chalcohalide thin films in efficient photovoltaics. MIBS can also be more broadly applied as a tool to accelerate the development of new anisotropic solar absorbers.
Microwave detection of cancer cells based on physiological cell properties
Supervisor: Prof Norbert Klein
This PhD project is aiming to develop microfluidic methods for label free detection of tumour cells based on physiological cell properties like cell size, hydration level and electronic properties (see research website https://www.imperial.ac.uk/people/n.klein/research.html). Microwave radiation penetrates through the cell membrane, allowing an unshielded view into the cell interior. The project will be continuation of a previous PhD project on this topic, and will include cell manipulation by dielectrophoresis. The student will work as member of an interdisciplinary team of physicists, engineers and life scientists and will receive training in microfabrication and microfluidic technology, microwave and electromagnetic measurement techniques, and biomedical device assessment in a clinical environment. We are aiming to develop of novel tool for liquid biopsies, which will potentially reduce the use of tissue biopsies for monitoring tumour progression and improve the accuracy of early stage cancer detection. Candidates should have a passion for this topic and a master’s degree in Physics, Materials Science, Electrical- or Bioengineering or related disciplines. The student will use our clean room facilities for the preparation of microfluidic channels and our unique microwave and cell characterization laboratory with state-of-art microwave network analysers, microfluidic equipment and fluorescence microscopy for device characterization and clinical applications.
Multiplexed detection of disease/cancer biomarkers using graphene sensor arrays for point-of-care diagnosis
Supervisor: Prof Norbert Klein
Detection of several disease markers simultaneously in real time using simple, low-cost and miniaturized devices on one chip is a first step toward personal disease diagnosis. This PhD project is aiming to develop a platform for electrical detection of several disease markers using graphene-field-effect-transistor sensors arrays. This project will be a continuation of our recent work on the detection of exosomes using graphene-field-effect-transistor sensors (see research website https://www.imperial.ac.uk/people/n.klein/research.html). The student will work as member of an interdisciplinary team of physicists, engineers and life scientists and will receive professional training in clean room techniques and graphene preparation, electrical device characterization and microfluidic technology. She/he will use our cleanroom facilities to fabricate arrays of graphene-field-effect transistors using microfabrication techniques, functionalize the transistors using specific linker molecules, design 3D moulds for incorporating different antibodies onto specific graphene sensors, and integrate the transistor array with microfluidic channels and carry out the electrical measurements. This project is particularly important for the detection of early stages of cancer and could be a powerful tool towards personal medicine. Candidates should have a passion for this topic and a master’s degree in Physics, Materials Science, Electrical- or Bioengineering or related disciplines.
Quantum spin materials
Supervisor: Dr Mark Oxborrow
The field of quantum technology (Q-tech) stands to revolutionize computing, communications and sensing. Like its predecessors (e.g. CMOS), this new technology is implemented on actual hardware –devices– which are in turn based on particular materials or combinations thereof. Many of these quantum materials store information/coherence as specifically oriented (i.e. “polarized”) spins. Engineering materials that can be strongly spin-polarized, where the polarization persists for a long time, is absolutely critical to the success of Q-tech. To date, a few “magic” spin materials have been found and extensively exploited; these include isotopically purified silicon doped with phosphorus, NV centres in diamond, and pentacene-doped paraterphenyl. But better-performing, more easily fabricated and configurable materials are sought. This project will involve the identification, synthesis/fabrication and characterization of new quantum spin materials optimized for specific Q-tech applications, in particular for detecting single microwave photons. The unique equipment/rigs needed to characterize these materials must often be home-made. Students with strong electronics/physics hacking skills as well as students with knowledge of physical chemistry are thus encouraged to apply. The work is highly creative and interdisciplinary.
Nanotechnology and Nanoscale Characterisation
Atomic-scale design of electrocatalysts for renewable energy conversion and storage in energy-rich fuels
Project supervisor: Dr Ludmilla Steier
Rapidly decarbonizing our electricity, transport and industrial sectors has become one of the most pressing challenges of modern society, research and industry. Such a restructuring requires new clean fuels for the transport sector, new green synthesis routes in the chemical industry (i.e. hydrocarbon synthesis), and scalable energy storage options. As electricity generation from renewables becomes cheaper, large-scale synthesis of fuels and chemicals via electrocatalysis of CO2 and water to energy-rich fuels is particularly attractive. Copper is one of the catalysts that is able to yield C2+ products such as ethylene, ethanol and others, but tailoring the catalyst selectivity towards one specific product remains a challenge. Often, only H2, CO and other C1 products are observed.
The aim of this project is to understand how yield and selectivity in the CO2 reduction reaction (CO2RR) on copper electrodes (metallic copper and its oxides) can be tailored towards a single product. The approach will be to alter the electrode surface composition using atomic layer deposition (ALD) and understand the function of the ALD-modified surface in the catalytic reaction. ALD is a thin film deposition technique able to control material growth down to a monolayer or even thinner on flat substrates as well as within high aspect ratio nanostructures. As such, active sites can be engineered with atomic precision and their electrocatalytic performance can be studied on flat model systems as well as in high surface area electrode architectures. The emphasis on material characterisation will lie on the catalyst surface including the identification of the catalytically active site(s) (is it one single metal centre, a bimetallic active site, metal centre/defect, metal centre/oxide interface?) using state-of-the-art surface characterisation and operando electrochemical techniques.
You will have the opportunity to work amongst and learn from an interdisciplinary and supportive network of top researchers across Imperial College London with expertise in surface science, nanomaterials, catalysis and modelling theory, and connect to a cohort of PhD students and postdoctoral researchers through collaborations, research seminars and networking events.
Dissolution, sorting, and assembly of SWNTs for transparent electrodes, thin film transistors, and composites
Supervisor: Prof Milo Shaffer
Carbon-based electrodes promise cheap, printable, flexible, transparent conductors and high performance thin film resistors, crucial for the development of large area plastic electronics. The use of long, metallic nanotubes should provide the required significant improvements in transparent conducting network performance. Long SWNTs are also especially promising for high performance nanocomposite fibres with exceptional strength and toughness. A recently developed process allows dissolution of single-walled nanotubes (SWNTs), without any damaging oxidation or sonication. In principle, very long SWNTs can be dispersed by this method, which are truly individualised in solution due to electrostatic repulsion. The charge can be neutralised, or exploited to control the deposition process, including creating hybrid composite films, fibres, and 3d networks. Other SWNT fractions are of interest for transistors and other plastic electronics applications.
A variety of projects are available to exploit this technology in different contexts. One area aims to exploit transparent conductive and semi-conducting films produced from SWNTs for improved, proof-of-concept device structures for transistors, LEDs and PV. Protocols for SWNT deposition on plastic films, by physical and chemical means, will be developed. Another area will focus on rational assembly, controlling the assembly of junctions of SWNTs with specific geometry and morphology. A third area will focus on mechanical performance, creating a new generation of high performance ductile composites.
Spinning ultra tough, self-healing, and multifunctional nanostructured fibres
Supervisor: Prof Milo Shaffer
Exploiting the undoubtedly exceptional properties of individual nanostructures in macroscopic structures is challenging. Anisotropic nanoparticles provide the load‑transfer required for efficient mechanical reinforcement, however, they must be aligned, at high loading, without agglomeration, within a matrix. High strength fibers are an ideal context to develop nanocomposite systems, using just small quantities of material. Fibers represent the state-of-the-art of high specific strength materials and are combined with resins to produce high performance composite structures in a wide range of applications. Nanocomposite fibers provide an extra level of structural hierarchy, reminiscent of many natural materials, such as wood or bone. Mechanical efficiency in such fibers not only depends on the type of nanoreinforcement, including aspect ratio, length, surface chemistry/interfacial properties and intrinsic stiffness/strength, but also on the fiber microstructure including the matrix crystallinity and orientation of the constituents.
One dimensional (1D) nanofillers are particularly well-suited to reinforce structural fibers, since they match the dimensionality, can pack efficiently, and can offer high aspect ratios. Carbon nanotubes can used to reinforce composites/fibers, can provide high (specific) strength and stiffness, and other functional properties, and may even displace conventional carbon fibres for lightweight, energy-efficient vehicles. This project will focus on wet‑spinning from nematic liquid crystalline phases of single-walled carbon nanotubes (SWCNTs) to produce dense and highly ordered fibers have been produced with an exceptional balance of high strength and electrical/thermal conductivity. Related methods will be used to create self-healing fibres from inorganic nanotubes and synthetic proteins
Theory and Simulation of Materials
Computational investigation of Mg corrosion
Supervisor: Prof Andrew Horsfield
Magnesium is remarkable for its high strength to weight ratio, making it highly attractive for applications where being able to be moved is important (notably transport and personal electronics). However, it has a famous downside: it reacts readily with air and water. As the resulting mix of magnesium oxide and hydroxide is unable to protect the underlying metal, extensive corrosion can often result. Further, the precise rate of corrosion is highly sensitive to small amounts of added elements (notably iron). There have been numerous and extensive experimental studies, but without assistance from theory and simulation a proper mechanistic understanding is hard to achieve. In this project we will develop and apply a range of simulation techniques (from DFT to phase field) to reveal the underlying processes that enable corrosion. The ultimate aim is to propose ways that corrosion in magnesium can be inhibited in a cost efficient way.
Crystal dynamics of halide perovskite solar cells
Supervisor: Prof Aron Walsh
Metal halide perovskites are being widely studied for applications including light-emitting diodes, solar cells, and neuromorphic computing. These materials are mixed ionic-electronic conductors that can absorb and emit light with exceptional efficiency [1,2]. Halide perovskites are mechanically soft, and the presence of a dipole on the molecular sublattice leads to polarisation behaviour that varies across length and time scales. The large nuclear charge of the Pb ion leads to a spin-orbit coupling that gives rise to a Rashba splitting of the electronic structure. This project will focus on the thermal motion of ions inside these crystals and the coupling to external electromagnetic fields. It will involve molecular dynamics to probe real-time trajectories and excited state simulations that include point and extended defects. The position would be suitable for those with a background in chemistry, physics, or materials science with an interest in computers and structure-property relationships of crystals.
1. Taking control of ion transport in halide perovskite solar cells, ACS Energy Letters 3, 1983 (2018); https://pubs.acs.org/doi/10.1021/acsenergylett.8b00764
2. Point defect engineering in thin-film solar cells, Nature Reviews Material 3, 194 (2018); https://www.nature.com/articles/s41578-018-0026-7
Data-driven materials discovery for next-generation solar energy conversion
Supervisor: Prof Aron Walsh
The conversion of sunlight to electricity is possible through the photovoltaic effect. A photochemical reaction can be used to generate a chemical feedstock such as hydrogen. The efficiency of both processes relies on the ability of the active material to absorb light and transport charge. While silicon-based solar energy technologies are well-established, the search for low-cost and high-efficiency alternatives continues. Building on the recent progress in our group [1,2], this project will develop and apply the latest tools in materials discovery incorporating databases, electronic structure theory, and machine learning. The position would be suitable for those with a background in chemistry, physics, or materials science with an interest in scientific computing and renewable energy.
1. Machine learning for molecular and materials science, Nature 559, 547 (2018); https://doi.org/10.1038/s41586-018-0337-2
2. Identification of killer defects in kesterite thin-film solar cells, ACS Energy Letters 3, 496 (2018); https://pubs.acs.org/doi/abs/10.1021/acsenergylett.7b01313
Development and application of first-principles and molecular modelling tools for the theory and simulation of materials
Supervisor: Prof Arash Mostofi
Materials underpin every modern technology and are ubiquitous in our lives, from components that make up jet aircraft, to transistors in computer chips. Our research group (www.mostofigroup.org) is dedicated to the application and development of theory and computational simulation tools for understanding and predicting the behaviour of materials from the atomic length-scale up.
We use quantum mechanics to describe systems of interacting electrons and nuclei, an approach that is often called ab initio, or first-principles, and which is invaluable for providing microscopic insight into the macroscopic behaviour of materials.
A key focus of our work is to push towards developing predictive understanding of real materials and devices, i.e., structurally complex and heterogeneous systems that correspond more closely to reality.
Current lines of research in the group span a broad range of phenomena and materials, including:
+ complex oxides (multifunctional properties, symmetry-breaking, superconductivity)
+ 2D materials (electronic and optical properties, defect and adsorbate engineering)
+ twisted bilayer materials (strong electron correlations, superconductivity)
+ polymer nanocomposites (mechanical strength and failure mechanisms)
+ metal-polymer interfaces (structure, charge injection and transport)
+ development of methods and software for electronic structure simulations [ONETEP (www.onetep.org); Wannier90 (www.wannier.org)]
PhD project topics are available in all of the above areas and interested candidates are encouraged to look at the group’s recent publications at www.mostofigroup.org and to contact firstname.lastname@example.org to discuss projects and funding opportunities.
Exploring quantum computing for materials simulation
Supervisor: Prof Peter Haynes
The simulation of quantum materials and molecules have been identified as promising early applications of quantum computers due to the equivalence of entanglement and the correlation of the motion of electrons . The so-called era of Noisy Intermediate-Scale Quantum (NISQ) technology  is just around the corner and promises universal quantum computing with 50–100 qubits that are capable of performing tasks beyond classical computers but limited by noise in the number of quantum gates that can be connected into a circuit to execute a given quantum algorithm. Simulations of small molecules and simple models of materials have already been demonstrated on six-qubit hardware  and 20-qubit machines are now available. This project will be associated with a collaboration with Professors Myungshik Kim and Johannes Knolle in Physics and funded by Samsung. We will apply emerging algorithms for quantum computers such as variational quantum eigensolvers to more realistic models of polymers and molecules parametrised by first-principles simulations on classical computers.
- Richard Feynman, Int. J. Theor. Physics 21, 467–488 (1982)
- John Preskill, https://arxiv.org/abs/1801.00862
- Abhinav Kandala et al., Nature 459, 242–246 (2017)
How do materials melt at the atomic scale?
Supervisor: Prof Robin Grimes
It is straight forward to model the melting of single component metals and simple binary compounds such as oxides. Molecular dynamics is good at following the solid/liquid interface as it moves into the solid. But when the solid has two or more components, phase diagrams tell us that at equilibrium the solid and liquid have different compositions. The liquid is dissolving a solid of a different composition. What happens at the interface? How do the atomic scale kinetic processes of diffusion at the interface control dissolution into the viscous liquid? Despite being poorly understood, this atomic scale phenomenon controls general processes from solidification in metals processing to liquid phase sintering in ceramics but also specific issues such as the progression of accidents in a nuclear reactor core. In this project we will use molecular dynamics to consider binary metallic systems for joining applications and refractory oxides in the nuclear industry. We will collaborate with colleagues in the metals processing group at Imperial and the nuclear group at the University if New South Wales in Australia.
Modelling solar energy conversion at the nanoscale
Supervisor: Dr Johannes Lischner
Nanomaterials have extraordinary properties that can be harnessed in novel types of energy conversion devices, such as solar cells or photocatalysts. For example, metallic nanoparticles absorb sunlight through the excitation of plasmons, collective oscillations of the electrons. The plasmons decay into energetic or “hot” electrons and holes that can be collected or used to trigger chemical reactions. In this project, we try to understand the ultrafast dynamics of electrons, light and lattice vibrations in nanomaterials using advanced modelling techniques that were recently developed in our group [1,2,3]. We want to learn how to control energy conversion at the nanoscale through the composition, geometry and environment of the nanomaterial. We work closely with experimental groups to test the predictions of our models.
 Dal Forno, Ranno, Lischner, J. Phys. Chem. C 122, 8517 (2018)
 Ranno, Dal Forno, Lischner, npj Computational Materials 4, 31 (2018)
 Castellanos, Hess, Lischner, Communications Physics 2, 47 (2019)
Multiscale simulations of pressure-induced structural transformations in nanomaterials
Supervisor: Prof Peter Haynes
Nanoscale systems, such as nanocrystals, nanorods and tetrapods, show a wealth of distinctive behaviours with respect to their bulk counterparts, which can be controlled by varying their size, shape and surface. One interesting aspect is the effect of pressure on their structural stability and transformation pathways. Technologically important nanocrystals of tetrahedrally coordinated materials (e.g. Si, Ge, CdSe, CdS and ice) can be driven by pressure toward novel ordered or disordered (meta-)stable phases at the same conditions as crystalline transitions in the bulk.
The nature of the transformation (see figure) and the resulting structures in very small systems are qualitatively different from those of larger systems, as observed in both simulations and experiments. In collaboration with Professor Carla Molteni at King’s College London, this project aims to understand in detail how the size, the nature of the chemical bond and the details of the surface affect the interplay between ordered and disordered structures when pressure is applied to (and released from) tetrahedrally coordinated nanomaterials.
Building on our previous work1 that established a successful experimental collaboration2 we aim to predict the conditions that favour transformations to crystalline rather than amorphous phases and result in desirable properties. We will achieve this by simulating small semiconductor nanocrystals under pressure using a set of computational techniques: molecular dynamics with empirical potentials, metadynamics to enhance the sampling and avoid over-pressurisation, and density functional theory-based methods for the opto-electonic properties3. Crucially our atomistic simulations will be complemented by experiments on small semiconductor nanocrystals under pressure. We will focus on Ge and CdS/CdSe systems, as prototypical examples of covalent versus ionic semiconductors.
Graphical abstract from Ref. 2: evolution of a Ge nanocrystal under increasing pressure (left) – comparison of structure and electronic density obtained from simulation (top, middle) with optical transmission experiments (bottom); qualitative difference in nature of the transition between bulk and nanocrystal (right).
N. R. C. Corsini et al., J. Chem. Phys. 139, 084117 (2013), DOI: 10.1063/1.4819132; C. Bealing et al., Phys. Chem. Chem. Phys. 12, 8542 (2010), DOI:10.1039/C004053C