Diamond Concise Annual Review 2020/21

24 25 D I A M O N D L I G H T S O U R C E A N N U A L R E V I E W 2 0 2 0 / 2 1 Crystallography Group T he Crystallography Group at Diamond Light Source comprises the High-Resolution Powder Diffraction beamline (I11), the Extreme Conditions beamline (I15), the X-ray Pair Distribution Function (XPDF) beamline (I15-1) and the Small-Molecule Single-Crystal Diffraction beamline (I19). Bringing these beamlines together into one science group means we can fully exploit the technical and scientific expertise within its teams to provide the basis for future development and pioneering experiments. Studies in the past year have included those to improve the capacity and function of lithium-ion batteries for electric vehicles, developmore accurate risk models of volcanic eruptions and optimise the design of Prussian blue analogues, an important family of materials used in a variety of industrial applications. Improving performance of lithium ion batteries Researchers are using Diamond facilities to make dramatic progress in the development of lithium-ion (Li-ion) battery technology. Although layered nickel- rich lithium transition metal oxides offer excellent energy densities when used as cathodes for electric vehicle batteries, this group of materials suffers from rapid performance loss. It is therefore essential to understand the degradation mechanisms at the material level, particularly during long-term ageing. The team, from the Universities of Cambridge and Liverpool, the Faraday Institution and Diamond Light Source, used the Long Duration Experiments (LDE) facility on beamline (I11) to track the evolution of the crystal structure of battery materials operando over several months. The results showed that a portion of the cathode material cannot reach the fully charged state progressively over time. Combining the results from multiple techniques, the team suggested that this was caused by a ’pinning’ mechanism, where the crystal lattice of the material is pinned by its surface, preventing the material from being fully charged. These layered nickel-rich lithium transition metal oxides are likely to be the most popular cathode materials for the foreseeable future and so these findings will help in the development of strategies to mitigate degradation and optimise the function of Li-ion batteries. Xu C. et al. DOI: 10.1038/s41563-020-0767-8 Predicting explosive volcanic eruptions Highviscositymagmaoftencausesexplosiveanddamagingvolcaniceruptions. However, current knowledge of the mechanisms that regulate the style of volcanic eruptions fails to explain the anomaly that some volcanoes with low viscosity magmas have unexpectedly explosive eruptions. Recent observations have shown that magmas may contain nanometric crystals (nanolites) 10,000 times smaller than the width of a human hair, whose formation and influence on both viscosity and bubble formation is unknown. An international team of researchers used the Extreme Conditions beamline (I15) and the Small Angle Scattering & Diffraction beamline (I22) at Diamond Light Source to subject a basaltic magma that had been erupted explosively to X-ray diffraction measurements at high temperature (900-1500 Celsius) by varying the cooling rate.This allowed the in situ observation of nanolite formation and growth. Results showed that nanolites can form within milliseconds during rapid cooling, grow to ~50 nm in two minutes, and even aggregate. These new aggregates effectively disrupt the remaining free liquid flow, increasing the magma’s viscosity and resulting in an explosive eruption. These important findings will provide data for new numerical models of volcanic eruptions that will provide risk scenarios in volcanic areas. Di Genova D. et al. DOI: 10.1126/sciadv.abb0413 Optimising the design of catalysts, batteries and gas storage facilities Studies on the Small-Molecule Single-Crystal Diffraction beamline (I19) at Diamond Light Source are providing the data needed to improve a variety of important industrial materials called Prussian blue analogues (PBAs). These are a broad family of microporous inorganic solids used in batteries, hydrogen gas storage and as catalysts to make high-value chemicals. These materials have a disordered three-dimensional network of pores that allow ions or molecules to be moved or stored but until now this structure has not been identified. An international team of researchers investigated the pore structures of a range of PBAs to determine their characteristics. Using beamline I19 allowed them to measure the single-crystal X-ray diffuse scattering patterns of various PBA crystals. Their results show that the pore networks of all PBAs, although disordered, are far from random. The patterns that persist within these non-random network structures affect the physical properties of the materials, such as their ability to store gases or the rate at which ions can be moved in and out. These findings suggest that there is scope for tuning the type of disorder present by varying the composition and synthesis route of the PBAs, and that this could produce improved materials for use in a variety of industrial applications. Simonov A. et al. DOI: 10.1038/s41586-020-1980-y