The European Synchrotron Radiation Facility (ESRF) is a joint research facility situated in Grenoble, France, supported by 22 countries (13 member countries: France, Germany, Italy, the UK, Spain, Switzerland, Belgium, the Netherlands, Denmark, Finland, Norway, Sweden, Russia; and 9 associate countries: Austria, Portugal, Israel, Poland, the Czech Republic, Hungary, Slovakia, India and South Africa).Some 8,000 scientists visit this particle accelerator each year, conducting upwards of 2,000 experiments and producing around 1,800 scientific publications.
The presence of local residual stresses within fully recrystallized grains has attracted increasing interest in connection with shear-coupled grain boundary migration mechanisms for grain growth. In this work, we provide the first non-destructive, bulk three-dimensional measurements of intragranular residual elastic strain variations in fully recrystallized commercial-purity iron using dark-field X-ray microscopy (DFXM). For the first time, relative strain variations on the order of 10-4 are resolved within individual grains in the bulk, revealing heterogeneous strain distributions across all measured grains. In grains containing second-phase particles, dislocation accumulation is observed along with a localized strain signature with no detectable long-range effect. Crucially, the persistence of measurable residual elastic strain even in particle-free grains demonstrates that intragranular strain heterogeneity is an intrinsic feature of recrystallized microstructures. Such strain variations may play a non-negligible role in driving grain boundary migration during grain growth. This work calls for the explicit incorporation of intragranular residual elastic strains into future grain growth models.
The electrochemical conversion of CO2 to CO in membrane electrode assembly (MEA) electrolyzers using gas diffusion electrodes (GDEs) offers a sustainable and scalable pathway for carbon utilization. Here, we present a one-step atomic layer deposition (ALD) approach to prepare ZnO-based GDEs with tunable loadings and high selectivity toward CO. Increasing the number of ALD cycles raises the ZnO loading but progressively reduces the pore accessibility within the GDE. An optimal balance is achieved at 200 ALD cycles, delivering a peak CO faradaic efficiency (FECO) of 88% and a full-cell energy efficiency of 38% at-100 mA cm-2. Crucially, the scalability of ALD is demonstrated through stable long-term testing, achieving 85% FECO in a 5 cm2 MEA after 30 h, and 80% FECO in a 100 cm2 MEA after 24 h. These results establish ALD as an effective and versatile strategy for fabricating high-performance ZnO electrodes for CO2 electrolysis.
White and turquoise Ca-antimonate tesserae from Noheda (Spain) were characterized using LA-ICP-MS, XRD, SEM, and XANES spectroscopy to investigate their composition, crystalline phases, and opacification mechanisms. White tesserae contain a single Ca-antimonate phase (CaSb2O6 or Ca2Sb2O7), controlled by MgO content and thermal conditions, while most turquoise tesserae exhibit both phases and more heterogeneous compositions. XANES analysis reveals that antimony occurs predominantly as Sb5 + in turquoise glasses, while the copper redox state varies with concentration and source, showing limited interaction with Sb. Experimental reproductions demonstrate that in situ crystallization and crystal addition produce distinct microstructures, with copper selectively inhibiting crystal growth only via the in situ pathway. These findings offer new insights into Roman glass production practices and opacification technologies.
Resolving chemical species at the submicrometer scale is crucial in Heritage Science, where synchrotron radiation (SR)-based X-ray methods, including µ-XRF mapping and µ-XANES spectroscopy, offer unique insights into the composition of heterogeneous and opaque materials, such as degraded inorganic pigments in paintings. However, the high intensity and brightness of SR beams pose significant risks of radiation damage, which can compromise both sample integrity and data interpretation. This challenge is notably evident in Prussian blue (a ferric hexacyanoferrate pigment), where X-ray induced photoreduction of Fe3+ to Fe2+ interferes with speciation analysis in faded artworks, necessitating rigorous experimental strategies to ensure data reliability. To address this, we present a multi-scale and multi-technique approach aimed at safely investigating the light-induced degradation of Prussian blue in oil paintings via SR-based X-ray micro-spectroscopic techniques. The study focuses on the 1802 painting Pamphilus and his Servant Davus by the Danish artist Nicolai Abildgaard (Copenhagen, 1743-Frederiksdal, 1809), which exhibits various degrees of fading in the Prussian blue-based paints, particularly evident when comparing light-exposed areas to those protected by the frame. After evaluating the paint composition and fading at the macro-scale using a set of non-invasive MOLAB techniques (namely colorimetry, reflectance UV–VIS–NIR and external reflection mode FT-IR spectroscopies), two micro-samples from light-exposed and unexposed areas were selected for SR-based µ-XRF mapping and µ-XANES spectroscopy at the Fe K-edge. In parallel, a series of Prussian blue-based oil paint mock-ups were prepared, photoaged, and analyzed in advance of historical samples to establish optimal conditions for mitigating SR X-ray induced Fe3+→Fe2+ reduction during measurements, achieved by systematically varying fluence, dose, and temperature. Under these optimized, non-damaging conditions, we successfully mapped the stratigraphic distribution of iron compounds at submicrometric resolution in the historical cross-sections. The results, unaffected by analytical artifacts, revealed the nature of the secondary products responsible for the observed fading in Abildgaard’s painting. Consequently, this research offers a validated experimental approach for future SR-based X-ray micro-spectroscopy studies of Prussian blue degradation in other artworks.
The aim of this study was to evaluate the potential of iroko inner bark as a naturally occurring, pre-impregnated, unidirectional fibrous preform for producing added-value, biobased composite materials. To this end, the secondary phloem was separated from the rest of the bark and then consolidated using a hot compression moulding process similar to that employed for processing sheet moulding compounds (SMCs) in the composites industry. An experimental procedure was also employed to extract the latex from the secondary phloem. Thermal and FTIR analyses suggested that the latex was primarily composed of proteins and polyisoprenes. The microstructure of the resulting composites was characterised using synchrotron-based 3D X-ray computed tomography. 3D images revealed significant consolidation of the secondary phloem induced by the compression moulding process. To evaluate the practical interest of these composites in specific engineering applications, experiments were carried out to analyse their mechanical performance, surface wettability, and hygroscopic behaviour in environments with high relative humidity. Mechanical tests revealed significant anisotropy, with high longitudinal stiffness and strength inherited from their intricate quasi-ordered fibrous architecture. The proposed approach allows biobased composite materials with interesting end-use properties to be produced without the use of any supplementary oil-based resin matrix.
