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High performance ceramics with high strength or hardness can withstand extremely severe shock loading, having been used in many critical protective applications. The rapid development of nanomaterials offers great potential for further improving the performance of protective materials to the next level. It has been confirmed both experimentally and theoretically that nanomaterials can exhibit much higher strength and/or hardness than their bulk parental counterparts, not only under general ambient conditions but also under high rate shock loadings. A recent Science paper has reported that ultra-high strength can be achieved for nanocrystalline materials under shock loading. Furthermore, composites allow for the combination of multiple advanced properties to produce a customisable behaviour. The increased utilization of such advanced ceramic composites under dynamic loading conditions requires an improved understanding of the relationship between high-rate/shockwave response as a function of micro-structure and even nano-structure. The corresponding relationship for single-phase materials is very different. In this context, three key Themes characterize the research: (1) design and synthesis of advanced nanocomposite materials; (2) elucidation and full (or fundamental) understanding of the nanostructure - shock response relationship; (3) prediction of the nanocomposites performance.

AMPLI addresses the general questions How does a weak signal be translated into a measurable one? How does an isolated event can induce a cascade of events that lead to a major effect? In cell biology, molecular conformational signaling is often the primary process by which cells respond to changes in their physical and chemical environments. It is reported that very small conformational changes (~1 Å) induced by external stress at the level of a molecular receptor outside a living cell can be transmitted across the cell membrane and amplified. A similar process, involving target entities (molecules, ions…) interacting with molecular probes on the surface of a sensor, can be envisaged as a mean of amplifying the transduction signal of host-guest recognition events, the molecular probe layer on the sensor surface playing the role of amplifier. Such a strategy opens new perspectives for trace detection through pushing away the detection limit. In a previous project (ANR-16-JTIC-0003-01) we developed an organic field effect sensor (O-FET) for the detection of alkali ions in solution with a sensitive layer composed of molecular probes grafted atop a lipid monolayer. Exceptional performances were demonstrated, including a limit of detection (LOD) in the attomolar range. However, the variations of the surface potential measured for such low ion concentrations cannot be explained purely by local variations of charge density associated to the ion – probes complexation events; we hypothesis that an amplification phenomenon must be involved. AMPLI’s general objective is to combine experimental work and molecular dynamics simulations to understand the effects leading to the unexpected macroscopic surface potential changes resulting from a few ion-probe complexation events at the surface of an organic monolayer and correlate this changes to the FET sensor response. Our main hypothesis is that surface potential amplification could result from a scenario involving three consecutive mechanisms : 1) a host-guest interaction inducing a molecular conformation change of the host molecule, leading to a reorientation of its molecular dipole moment, 2) a propagation of the conformation change within the sensitive layer through molecular interactions in a domino-like cascade process, 3) a reorganization of the charges distribution in the electrical double layer at the active layer-solution interface at large scale, responsible for an amplification of the surface potential changes measured with the FET sensor. Because there is no simple way to show that the amplified FET response is due to the propagation of the probes conformational change, we have defined a plan to reach this objective. Our strategy is to build well controlled surfaces of selected ionic probe and determine conditions for which a molecular conformational change, induced by the complexation of the probes with specific ions, would propagate in the layer through molecular interactions. These surfaces will be investigated by ATR-FTIR to study the change in molecular conformation and by KPFM to measure the change in surface potential. They will allow us to establish the relationship between the propagation of conformation change and surface potential variations. These surfaces will then be implemented in the FET to establish the relationship between the propagation of conformational change and FET response, i.e. surface potential variations.

Magnetic phenomena pervade the world around us and are used in a huge variety of practical devices, ranging from nanoscale data storage devices through electric motors to plasma fusion reactors. At a fundamental level, magnetism in solids comes from the coordinated actions of many atomic magnets. The atomic magnetism originates from the intrinsic spin and the orbital motion of the electrons, and the relative importance of spin and orbital magnetism depends on the particular magnetic atom and its environment. This project concerns magnetism in oxides containing heavy metal atoms such as ruthenium, molybdenum, osmium and rhenium. These atoms have partially filled 4d or 5d electronic orbitals with a large spin-orbit interaction which strongly entwines the spin and orbital magnetism. Until recently, the study of magnetism in the presence of strong spin-orbit coupling was confined to f-electron systems, but today there is increasing focus on 4d and 5d systems, in which the greater mobility of the electrons results in a more diverse range of phenomena. In the past few years, a large number of theoretical predictions have appeared for magnetic systems with strong spin-orbit coupling, but very few have been confirmed empirically. The predictions include: (i) materials whose atoms have no magnetism when in isolation but develop magnetism through interactions with neighbouring atoms, (ii) anisotropic, bond-directional magnetic couplings resulting in novel propagating magnetic modes, (iii) quantum-mechanically entangled spin and orbital liquid states with exotic emergent quasiparticle excitations, (iv) metal-insulator transitions driven by spin-orbit enhanced magnetic correlations, and (v) unconventional superconductivity of doped electrons mediated by magnetic fluctuations. The programme of research aims to search for and study these and other novel magnetic phases in 4d and 5d oxides. A significant challenge will be the growth of high quality single crystals, which are essential as samples for the experiments. To overcome this challenge we have assembled two leading crystal growers with a vast amount of relevant expertise, as well as a Project Partner, Prof Yamaura, who brings additional capability in high pressure synthesis. We shall perform measurements to probe the novel spin-orbital states in the materials of interest using state-of-the-art techniques at international synchrotron and neutron facilities. We shall collaborate with staff at the facilities, including our Project Partners the Diamond Light Source and Paul Scherrer Institute, as well as the European Synchrotron Radiation Facility in Grenoble and the ISIS spallation neutron source, to perform the measurements and develop the necessary techniques. Finally, we shall work with our theory Project Partners at the University of Toronto and collaborators to develop a detailed understanding of the new electronic and magnetic states we will uncover.