Until very recently the MASER could only be used in very specialist applications such as radio astronomy. The reason for this is that cryogenic cooling and to a lesser extent, high applied magnetic fields, prohibited mass production on the grounds of both complexity and cost. Despite the fact that the MASER was discovered before the LASER these issues meant that the latter, which does not need applied magnetic fields or cooling, saw widespread adoption in a huge range of applications from bar-code readers, laser discs to laser eye surgery. In 2013 Imperial and UCL were awarded an EPSRC funded research project to produce a room temperature MASER. Although we had preliminary observations that room temperature masing was possible we had not verified this in a different laboratory setting, nor did we have a clear idea of how the masing molecule interacted with light and which crystal orientations or dopant concentrations would be optimal. This collaboration was remarkably successful achieving all the objectives we set. Now, in what is another world first, the team has constructed a diamond MASER capable of continuous-wave operation at room temperature. Our previous research has concentrated solely on organic materials as the masing medium. In this proposal we will explore the potential of masing in inorganic materials at room temperature. In doing so we will obviate two key problems encountered with organics. Problem 1 - Decay rates: The primary obstacle that prevents continuous operation in organics is the relatively long lifetime of the lowest triplet sub-level, reducing the number of pentacenes available for optical pumping (bottleneck) and destroying the population inversion. Problem 2 - Heating: The organic gain medium, pentacene in p-terphenyl we first used to demonstrate a room temperature MASER cannot withstand a continuous illumination by a laser because the temperature of the terphenyl host rises above its melting point. Solution to both problems: a radical but exciting departure which will address both problems simultaneously is to explore high spin states in inorganic materials with high melting/decomposition temperature and favourable thermal conductivities (T.C.): such as diamond (M.P. 3550C; T.C. 2000 W/mK) and silicon carbide (2730C; T.C. 120 W/mK). Very recently we observed masing at room temperature in diamond exploiting NV centres. This means we can build upon a huge wealth of research in the UK and elsewhere on diamond NV centres. Again there is much research exploring defects in SiC that we can build on. We have initiated a collaboration with the group of Prof. Dr. Vladimir Dyakonov at Würzburg group who are currently exploring SiC. REF. https://arxiv.org/pdf/1709.00052.pdf Achieving this would further establish without doubt the UK as the key place to carry out fundamental research on the topic of room temperature MASERs.

Until very recently the MASER could only be used in very specialist applications such as radio astronomy. The reason for this is that cryogenic cooling and to a lesser extent, high applied magnetic fields, prohibited mass production on the grounds of both complexity and cost. Despite the fact that the MASER was discovered before the LASER these issues meant that the latter, which does not need applied magnetic fields or cooling, saw widespread adoption in a huge range of applications from bar-code readers, laser discs to laser eye surgery. In 2013 Imperial and UCL were awarded an EPSRC funded research project to produce a room temperature MASER. Although we had preliminary observations that room temperature masing was possible we had not verified this in a different laboratory setting, nor did we have a clear idea of how the masing molecule interacted with light and which crystal orientations or dopant concentrations would be optimal. This collaboration was remarkably successful achieving all the objectives we set. Now, in what is another world first, the team has constructed a diamond MASER capable of continuous-wave operation at room temperature. Our previous research has concentrated solely on organic materials as the masing medium. In this proposal we will explore the potential of masing in inorganic materials at room temperature. In doing so we will obviate two key problems encountered with organics. Problem 1 - Decay rates: The primary obstacle that prevents continuous operation in organics is the relatively long lifetime of the lowest triplet sub-level, reducing the number of pentacenes available for optical pumping (bottleneck) and destroying the population inversion. Problem 2 - Heating: The organic gain medium, pentacene in p-terphenyl we first used to demonstrate a room temperature MASER cannot withstand a continuous illumination by a laser because the temperature of the terphenyl host rises above its melting point. Solution to both problems: a radical but exciting departure which will address both problems simultaneously is to explore high spin states in inorganic materials with high melting/decomposition temperature and favourable thermal conductivities (T.C.): such as diamond (M.P. 3550C; T.C. 2000 W/mK) and silicon carbide (2730C; T.C. 120 W/mK). Very recently we observed masing at room temperature in diamond exploiting NV centres. This means we can build upon a huge wealth of research in the UK and elsewhere on diamond NV centres. Again there is much research exploring defects in SiC that we can build on. We have initiated a collaboration with the group of Prof. Dr. Vladimir Dyakonov at Würzburg group who are currently exploring SiC. REF. https://arxiv.org/pdf/1709.00052.pdf Achieving this would further establish without doubt the UK as the key place to carry out fundamental research on the topic of room temperature MASERs.

Discovery and development of advanced materials requires understanding and control of the relationship between composition, structure and function. In crystalline materials, there is considerable focus on a design process that is informed by a single macroscopic structure defined by the average crystallographic unit cell determined by Bragg diffraction. This is a powerful approach, but it has become increasingly apparent that local chemical and positional deviations from this long-range average view of the structure can have decisive effects even in crystalline systems. Charge stripes in the high temperature superconductors and the role of "panoscopic" order spanning meso- to nano-scopic length scales in thermoelectric performance are just two examples of the limitations of average structure considerations in explaining how an apparently small compositional change can transform functional behaviour. This in turn restricts the utility of such a view of structure in designing new materials with enhanced performance. This is particularly critical for the many functional materials in which modulation or switching of a ferroic order parameter (i.e., polarization or magnetization) by a stimulus such as an applied field produces the property (e.g., piezoelectricity or magnetoresistance) used in devices (e.g., actuators or data storage). Their properties are optimised by formation of solid solutions e.g., in PbZrO3-PbTiO3 (PZT), responsible for >90% of piezoelectric devices, the Zr/Ti ratio is adjusted to coincide with the boundary between rhombohedral and tetragonal symmetries, at which the piezoelectric charge coefficient maximizes. There is competition between the randomising effect of the local configuration of Zr and Ti cations (which occupy the same position in the average unit cell, but locally exert quite different influences on the displacements producing the polarisation) and the effect of the long-range dipolar and elastic interactions favouring the average polarisation direction. This local structure effect and the finite size correlations it produces exerts decisive control of function that is invisible from the average structure central to traditional design. The properties of the solid solutions are thus not an average of the end members, and simple design rules do not exist. The project team have recently shown how design based on quantitative local structure analysis can afford materials families with important properties that had not been accessed by classical average structure design approaches. Using nanoscale information from total Bragg scattering studies to control properties, they identified chemistry that would have been disregarded based on the average structure but led to a new lead-free piezoelectric family (Advanced Materials 2015) and then to the first bulk room temperature ferromagnetic ferroelectric multiferroic (Nature 2015): combination of these two long range orders in a single phase has been a longstanding scientific challenge. This project will develop the control of function by understanding and manipulating symmetry and structure beyond the unit cell length scale. We will build a toolkit that enables this approach by combining solid state materials chemistry, materials science and condensed matter physics to integrate synthesis, crystal chemistry, crystallography, local structure analysis, scanning probe microscopy, magnetism, electroceramic measurement physics, and materials processing. The toolkit exploits the synergies between the skills of the two participating groups. By designing then preparing new piezoelectric and multiferroic materials, we will demonstrate how this approach can guide synthesis for function, with ramifications for control of properties beyond the exemplar areas studied, for example in heterogeneous catalyst and electrode (fuel cell, battery) materials, contributing to the EPSRC Physical Sciences Grand Challenge of Nanoscale Design of Functional Materials.

The world around us is full of modern technology designed to make our lives safer, more comfortable and more efficient. Such technology is made possible by materials and devices that are able to interact with their surrounding environment either by sensing or acting upon it. Examples of such devices include motion detectors, fuel injectors, engine sensors and medical diagnostic tools. These interactive devices contain functional materials that can pose health hazards, are obtained from parts of the world where supply cannot be guaranteed or are relatively scarce. If access to these functional materials is restricted, many of these advances will no longer be available resulting in a reduction in living standards and decreased UK economic growth. There already exist a number of replacement materials that can provide the same functions without the same levels of concerns around safety, security of supply and sustainability. However, these replacement materials need to be manufactured using different processes compared to existing materials. This project explores new manufacturing technologies that could be used to create interactive devices that contains less harmful and sustainable materials with a secure supply. This project will focus on two types of material - thermoelectric and piezoelectric - where the replacement materials share a set of common challenges: they need to be processed at elevated temperatures; they contain elements that evaporate at high temperatures (making high temperature processing and processing of small elements difficult); they are mechanically fragile making it difficult to shape the materials by cutting, grinding or polishing; they are chemically stable making it difficult to shape them by etching; and many are air and moisture sensitive. The proposed research will address these challenges through three parallel research streams that proactively engage with industry. The first stream is composed of six manufacturing capability projects designed to develop the core manufacturing capabilities and know-how to support the programme. The second is a series of short term feasibility studies, conducted in collaboration with industry, to explore novel manufacturing concepts and evaluate their potential opportunities. Finally, the third stream will deliver focussed industrially orientated projects designed to develop specific manufacturing techniques for in an industrial manufacturing environment. The six manufacturing capability projects will address: 1) The production of functional material powders, using wet and dry controlled atmosphere techniques, needed as feedstock in the manufacture of bulk and printed functional materials. 2) How to produce functional materials while maintaining the required chemistry and microstructure to ensure high performance. Spark Plasma Sintering will be used to directly heat the materials and accelerate fusion of the individual powder particles using an electric current. 3) Printing of functional material inks to build up active devices without the need to assemble individual components. Combing industrially relevant printing processes, such as screen printing, with controlled rapid temperature treatments will create novel print manufacturing techniques capable of handling the substitute materials. 4) How to join and coat these new functional materials so that they can be assembled into a device or protected from harsh environments when in use. 5) The fitness of substituted material to be compatible with existing shaping and treatment stages found later in the manufacturing chain. 6) The need to ensure that the substitute materials do not pose an equal or greater risk within the manufacturing and product life cycle environment. Here lessons learned from comparable material systems will be used to help predict potential risks and exposures.