Periodic Reporting for period 3 - COMPLEXORDER (The Complexity Revolution: Exploiting Unconventional Order in Next-Generation Materials Design) Reporting period: 2021-10-01 to 2023-03-31 Summary of the context and overall objectives of the project This project is establishing how we might controllably introduce complexity into materials by varying chemical composition and synthesis, how we might then characterise these complex states, and how we might exploit this complexity when designing next-generation materials with unprecedented electronic, catalytic, photonic, information storage, dielectric, topological, and magnetic properties. Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far A few of the key areas on which our work has focussed so far are as follows:1. Prussian blue analogues. These are materials used in high-capacity batteries and as catalysts to make high-value organics. We have shown how the complexity of these materials might be controlled rationally to optimise their physical properties.2. Metal–organic frameworks. These are porous materials that can be used either to store gases reversibly (e.g. CO2) or as sensors for different molecules. We have been working on ways of exploiting complexity to engineer new types of mechanical flexibility in metal–organic frameworks that allow them to sense molecules in very specific ways and even to store information.3. Structural analogues of exotic electronic phases. Spin-ices are magnetic materials with a very unusual physics exploitable in `spintronic' materials. Their key limitation is the extremely low temperatures at which they operate (usually a few Kelvin – the temperature of outer space). We have been working on developing analogues of these materials that operate at room temperature. The secret has been to find structural analogues of electronic states. Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far) Our work on the project to date has made a number of important contributions both to the understanding of complex materials and also to the development of experimental techniques for characterising this complexity. In both respects, our results have pushed well beyond the state of the art. As the project progresses, we expect to make further contributions in both regards. A particular challenge in our sights is the development of robust general approaches for interpreting three-dimensional diffuse scattering patterns. X-ray scattering from a Prussian blue material of the type used in batteries
