Diamond Concise Annual Review 2020/21

26 27 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 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 T he Diamond Spectroscopy Group consists of four beamlines; the Microfocus Spectroscopy beamline, I18, the Core EXAFS (Extended X-ray Absorption Fine Structure) beamline, B18, and the two independently operating branches of the Versatile X-ray Absorption Spectroscopy beamline, I20-Scanning and I20-EDE (Energy Dispersive EXAFS). These four spectrometers are complementary in the energy ranges they cover, the size of their focussed beam spots delivered to the sample, and the time resolutions they are able to reach. This complementarity means that they can support research across many different scientific disciplines, from chemistry and catalysis through materials science, condensedmatter physics, environmental and life science, energy materials and cultural heritage. In the past year awidely diverse range of studies have included investigating theories on the formation ofmineral deposits onMars, locating new sources of rare earth elements and designing new sustainable materials used in catalysis. Understandingmineral formation on Mars Jarosite is a common mineral on Mars but scientists have failed to explain how it could have formed as it requires liquid water, iron-rich minerals and an acidic- oxidative environment. A group of scientists proposed an ‘ice-weathering model’ where the mineral was formed under glaciers.To test this theory, they studied deep Antarctic ice deposits for the presence of jarosite. An international team of researchers analysed samples of Antarctic ice on Diamond Light Source's beamline B18 using X-ray Absorption Spectroscopy (XAS) which allows data gathering on extremely diluted samples. The signature of jarosite was identified in X-ray absorption spectra, confirming that this mineral is present in Antarctic ice. The mineral was not present in surface ice but increased rapidly as the depth increased and it became the most abundant iron mineral in the bottom sections of the ice core. This suggested that jarosite was not originally deposited in snow but that it forms in deep ice, thus supporting the Mars ice-weathering model.This is an important finding and increases understanding of the geological and geochemical processes and the role of glaciers that shaped Mars. Baccolo G. et al. DOI: 10.1038/s41467-020-20705-z Locating new sources of rare earth elements Rare earth elements (REE) such as lanthanum and yttrium are essential for high-tech industries such as catalysts, magnets and rechargeable batteries. Over 80% of the world’s current heavy REE deposits are found in clay deposits in China and extraction methods have been developed with little regard for the natural environment. Intensive international research is ongoing to understand how these deposits form and how REEs are bound to them. This will aid identification of further sites around the world and the development of more environmentally- friendly methods of extraction. An international research team studied samples from China and a prospective site in Madagascar using Diamond Light Source's microfocus beamline I18 which allowed them to study the samples micron by micron. Combining X-ray Absorption Spectroscopy (XAS) with Scanning X-ray Fluorescence (SXRF) element mapping showed what surrounded themetals and their distribution in the sample. Although the rock samples from the two areas are different, the REE in both stick to the clay surfaces in an identical fashion. At the atomic level, the Madagascan clay deposits are the same as those currently exploited in China. These findings should allow us to develop easier, more environmentally friendly ways to extract these important elements and suggest that deposits may be more widespread than originally thought. Borst A. M. et al. DOI: 10.1038/s41467-020-17801-5 Designing new sustainable catalyst materials Catalysts are set to play an important role in reducing carbon emissions and other environmental pollutants. Nitrous oxide (N 2 O) is a by-product of fertiliser production, among other industrial processes, and has a global warming potential that it is approximately 310 times higher than carbon dioxide. The decomposition of N 2 O is traditionally achieved using catalysts based on precious metals, but a promising alternative is to use perovskite structures of mixed-metal oxides such as lanthanummanganite (LaMnO 3 ). This compound is currently prepared in a complex multi-step process at high temperatureandresearchersusedDiamondLightSource'sfacilitiesto investigate its production with a novel ball milling method with the aim of improving its catalytic properties. They used the Energy Dispersive EXAFS beamline (I20-EDE) to monitor how the structure changes with increasing pressure, using X-ray Absorption Fine Structure (XAFS) measurements in real-time. Complementary measurements on the Versatile Soft X-ray (VerSoX) beamline (B07) provided information on the surface properties of the materials during catalysis. This research provided important information on the conditions required to produce perovskite structures from ball milling, and shows the importance of synchrotron radiation methods in studying these materials, which is vital as researchers seek to develop sustainable methods for producing catalysts. Blackmore R. H. et al. DOI: 10.1039/d0cp00793e Spectroscopy Group The structure of lithium nitride including an Fe impurity.