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(Figure 70). S in both the micro- and nanoparticles existed predominately (up to 85%) as organic S, with a higher percentage of reduced and intermediate species such as thiols and sulfoxides than previously reported for materials from aerated soils [6,7]. Complementary oxalate extraction [8] of non-crystalline Al- and Fe-(hydr) oxides from leached colloids and nanoparticles indicated

that the sorption capacity of these phases could explain the quantities of P associated with Al and Fe in most leachates. Future work needs to further characterise these phases and their association with organic matter in leached particles, to help develop effective technologies for mitigating colloidal-driven eutrophication of water bodies near agricultural land.

PRINCIPAL PUBLICATION AND AUTHORS

Micro and nano sized particles in leachates from agricultural soils: Phosphorus and sulfur speciation by X-ray micro-spectroscopy. G.A. Adediran (a), D. Lundberg (b), G. Almkvist (b), A.E.P. Del Real (c), W. Klysubun (d), S. Hillier (a,e), J.P. Gustafsson (a), M. Simonsson (a), Water Res. 189, 116585 (2021); https:/doi.org/10.1016/j.watres.2020.116585 (a) Department of Soil and Environment, Swedish University of Agricultural Sciences (Sweden) (b) Department of Molecular Sciences, Swedish University of Agricultural Sciences (Sweden) (c) ESRF (d) Synchrotron Light Research Institute (Thailand) (e) The James Hutton Institute, Aberdeen (UK)

REFERENCES

[1] E. Sinha et al., Science 357, 405-408 (2017). [2] T. Murray et al., Front. Mar. Sci. 6, 47-53 (2019). [3] A.K. Eriksson et al., Soil Use and Management 29, 5-14 (2013). [4] J. Liu et al., Soil Sci. Soc. Am. J. 78, 47-53 (2014). [5] L.P.M. Lamers et al., Limnol. Oceanogr. 47, 585-593 (2002). [6] J. Prietzel et al., J. Plant Nutr. Soil Sci. 172, 393-403 (2009). [7] K. Boye et al., Eur. J. Soil Sci. 62, 874-881 (2011). [8] R.L. Parfitt, C.W. Childs, Aust. J. Soil Res. 26, 121-144 (1988).

Shedding light on invisible atomic scale point defects with 3D nanoscale resolution

Fusion power promises an almost limitless, low- carbon energy supply. However, the intense radiation produced by the process causes defects to form in the structure of reactor materials, which can dramatically degrade material properties. To shed new light on these defects, a new 3D nanoscale resolved microscopy approach, based on coherent X-ray diffraction imaging, has been developed. Most of the defects formed by irradiation are only a few atoms big, making them invisible to electron microscopy, the mainstay for atomic-scale defect characterisation. However, high concentrations of these defects can cause dramatic changes: embrittlement, increase in hardness by up to 100%, reduction in thermal diffusivity by more than 50% and swelling by several percent. A new paradigm that has recently emerged [1] is to use X-ray diffraction measurements of lattice strain to indirectly probe invisible defects via the strain fields they cause. However, these measurements could only resolve defect populations at the microscale, which is far too coarse to shed light on the nanoscale interactions that govern defect structure formation and evolution.

Using the excellent brilliance and coherence of beamline ID01, a new microscopy technique that allows the

measurement of lattice strain in extended crystalline objects at the nanoscale was developed. Based on the formerly proposed Bragg ptychography method [2], it uses coherent diffraction patterns produced by a sub- micron X-ray beam rastered across the sample. From these diffraction patterns, the morphology of the sample and the crystalline deformation, including dislocations, strain and tilts of the lattice planes, could be retrieved with a 3D spatial resolution below 40 nm (Figure 71). This was used to reveal the presence of otherwise invisible irradiation defects via the 3D nanoscale strain fields they cause. The key advance of the present approach is that, for the first time, the new reconstruction approach makes it possible to take imperfections of the illuminating X-ray beam into account and, through angular up-sampling of the diffraction data and simultaneous retrieval of the probe, enables a greatly extended field of view. Moreover, an improvement in data acquisition efficiency by about a factor of 10 could be estimated, thanks to the up-sampling strategy.

This new microscopy technique was applied to tungsten, the front-runner material for fusion reactor armour. It enabled imaging of the complex 3D lattice distortions caused by defects due to helium-ion irradiation, which mimics the damage expected in armour components during fusion reactor operation. The enhanced 3D resolution of this technique made it possible to identify and exclude unwanted artefacts at sample surfaces that are caused by sample preparation, avoiding strong bias in the subsequent structural analysis (Figure 72).