The hydrogen storage properties of Hf1-xTixNbVZr high entropy alloys (HEAs) synthesized by arc melting have been investigated. The first hydrogenation of the alloys was performed at room temperature under 20 bars of hydrogen pressure. Results show an increase in gravimetric hydrogen content with Ti substitutions. Upon hydrogenation, the multiphase alloys (x = 0 and x = 0.25) exhibit a combination of faces-centred-cubic (FCC) hydride and C15 Laves phases, while single-phase alloys (x = 0.5, 0.75, and 1) display FCC structures. The crystal structure evolution during dehydrogenation of HfNbVZr (x = 0) and TiNbVZr (x = 1) HEAs was examined using in-situ neutron diffraction. The analysis demonstrates temperature-dependent desorption behaviour, with HfNbVZr displaying lower desorption temperatures compared to TiNbVZr. Additionally, in-situ neutron diffraction experiments during deuterium desorption indicate a two-step phase transition from FCC dihydride to BCT monohydride, followed by a transition to BCC.

Neutrons, owing to their unique properties, serve as indispensable probes for investigating the structure and dynamics of materials across various length scales. The scientific community utilizing neutron research infrastructures encompasses a diverse range of disciplines, making it challenging to quantify its scientific and societal impact. To address this challenge, we apply Natural Language Processing (NLP) and machine learning techniques to analyze the scientific output of the European neutron science community. Leveraging open-source software toolkits, our method allows for the quantitative assessment of community evolution and research focus. Our analysis reveals consistent growth in the neutron community despite a reduction in sources, underscoring the enduring significance of neutron methods in scientific research. Furthermore, an increase in unique authors and an even distribution of publications across diverse scientific topics highlight the community’s interdisciplinary nature and collaborative spirit. While this study emphasizes neutron scattering, our methodology holds promise for a broad range of scientific communities reliant on Large Research Infrastructures (LRIs), offering opportunities for collaboration, optimization of experimental approaches, and informed decision-making by governmental and funding bodies.

Correction for ‘Hybrid d0 and d10 electronic configurations promote photocatalytic activity of high-entropy oxides for CO2 conversion and water splitting’ by Jacqueline Hidalgo-Jiménez et al., J. Mater. Chem. A, 2024, 12, 31589–31602, https://doi.org/10.1039/D4TA04689G.

Neutron backscattering spectroscopy with sub-μeV energy resolution has profited over recent years from intensity gains enabled by a phase space transformation (PST) chopper, which is a fast-moving neutron optical component first proposed by Schelten and Alefeld (Internal Report No. Jül1954, KFA Jülich, 1984). Here, we present its principle, the considerations for our technical layout, the related challenges, the mechanical and neutron optical aspects, and tests related to the graphite mosaic crystals, moving with a center velocity of 243 m/s in the scattering plane perpendicular to the reciprocal lattice vector of the reflection. The reported tests of the graphite crystal quality are informative for other neutron optical applications. Our mechanically innovative, most compact PST chopper layout has proven its reliability during user operation in the backscattering spectrometer IN16B, and certain aspects of its design have already been adopted for another backscattering spectrometer. We report the relative intensity gain measured on the backscattering spectrometer IN16B, ILL.

The evolution of metallurgy is a fundamental aspect related to the knowledge of the technological level of ancient civilizations, for which the information was mostly part of an oral tradition. The ancient, preserved artefacts are the only keepers of this long gone knowledge. Most advanced non-invasive techniques provide us the key to access it. Neutron techniques are nowadays the only available approach for revealing, non-destructively and with good spatial resolution, the morphological and microstructural properties within the whole volume of densely composed artefacts such as bronze statues. Application of neutron methods allows us to learn about ancient artefact manufacturing methods and to study at a very detailed level the current conservation status in their different parts. As part of a research project dedicated to the study of ancient Asian bronzes led by the Rijksmuseum Metal Conservation Department, four statues from the Rijksmuseum Asian collection were analysed using non-invasive neutron techniques. In this work, we present the investigation of a South Indian bronze statuette depicting Shiva in the form of Chandrasekhara (AK-MAK-1291, c. 1000–1200 A.D.) by means of white beam tomography, energy-selective neutron imaging (performed on CONRAD-2 at HZB, DE, and on FISH at TU-Delft, NL), and neutron diffraction (on ENGIN-X at ISIS, UK). The application of neutron imaging revealed the inner structure of the statue and allowed us to investigate the conservation state and potential cracking on the surface and in the bulk, to understand the interconnection of the different sections of the statue, and to obtain clues about the manufacturing processes. These morphological and microstructural results were employed to guide neutron diffraction analyses that allowed us to precisely characterize compositional differences, the presence of dendrites and columnar growth peak structures related to casting. This work is a complete non-invasive analytical investigation on an archaeological bronze artefact, providing outstanding results: from a quantitative analysis of the composition and microstructure to an in-depth morphological analysis capable of unveiling details on the ancient casting methods of the statue.

Photocatalysis offers a sustainable solution for essential reactions such as CO2 conversion and water splitting, but constraints in catalyst properties like bandgap and active site availability often limit its efficiency. High-entropy oxides (HEOs), which incorporate five or more different cations, present significant potential for this application due to their elemental diversity. This study explores active HEO development for photocatalytic applications by integrating cations with d0 and d10 electronic configurations. A single-phase HEO with a monoclinic structure was successfully synthesized, comprising elements with d0 (titanium, zirconium, niobium and tantalum) and d10 (zinc) electronic configurations. Comprehensive analyses of its microstructure, chemical composition, optical properties and photocatalytic activity were conducted. The resulting TiZrNbTaZnO10 exhibited superior UV and visible light absorption, a low bandgap of 2.5 eV, minimal radiative electron-hole recombination and high stability under photocatalytic conditions. Remarkably, TiZrNbTaZnO10 outperformed the TiZrHfNbTaO11 photocatalyst which contains solely d0 electronic configuration. This enhanced performance is attributed to the mixed electronic configurations fostering heterogeneous chemical environments, which facilitate efficient charge carrier separation and transfer.

Neutron tomography is gaining popularity particularly in cultural heritage research, for non-destructively analysing the inner structure of bulk metal artefacts, such as bronzes, but the induced temporary decay radiation is often considered as a drawback. However, this delayed gamma-emission can be put to good use: by performing gamma spectroscopy after neutron tomography, the interior elemental composition of artefacts can be obtained “for free”. Inspired by this, we propose a ray-tracing approach to non-invasively quantify both interior geometry and elemental composition using only a single neutron tomography experiment. This strategy aligns well with both the aim for efficient use of neutron beam time and the expectation from curators and conservators for minimal neutron irradiation. Here, we outline the core principle of this method, demonstrate the extent of its quantification capability on bulk objects of known composition by fusing neutron tomography and delayed-gamma spectroscopy data sets. We also showcase its practical application on an ancient solid-cast Indonesian bronze statuette, by which we gain insights into how the pristine inner bronze segregated into a different composition than the surrounding shell. Similarly, the method allows us to quantify the composition of a hidden offering in the statuette that consecrates the bronze for worship purposes.

We studied the corrosion of Roman copper alloy coins that experienced alternations or progressive changes in their burial environment. We used coins that were still embedded in soil or in a concretion selected from three professional excataved sites - Berlicum and Krommenie in the Netherlands and Kempraten in Switserland. mCT scanning and neutron scanning were used to record the 3-D properties of these coins prior to (destructive) analyses. It proved possible to tentatively identify the coins. Microscope observations and SEM-EDX analyses revealed complex corrosion processes, related to changing burial environments. In soil horizon with fluctuating groundwater levels in a region with upwelling reducing, iron-rich groundwater, the copper in a gunmetal coin is essentially replaced by iron oxides while tin remains and forms tin-oxide bands. Fluctuating redox conditions in marine-influenced environments was shown to transform a copper-alloy coin into strongly laminated copper sulphides with embedded gypsum crystals, with an outer surface of copper and copper-iron sulphides. Burial of bronze in a charcoal rich layer probably caused temporary highly alkaline soil conditions. This caused most of the copper to leach from this coin, leaving behind a laminated tin-dominated mass, with only a limited amount of (malachite) corrosion products remaining in the surrounding groundmass. In all three cases, corrosion processes tend to be anisotropic, probably because of cold-hammering of the coins during their manufacture. Such corrosion processes on massive copper alloy coins may produce features that may lead to their incorrect classification as subferrati, i.e. copper alloy coins with an iron core. Our results may help in future to distinguish strongly corroded massive coins from subferrati.

The ANET project aims at developing 2D compact neutron collimators for neutron imaging applications. The results of the ANET collimator performances, presented in this communication, are based on data collected at the FISH beamline at TU-Delft. Two independent methods to evaluate the neutron radiography resolution are described and discussed, as well as a comparison of the beam divergence with or without the ANET collimator.

The structure of five rare filigree spheres from a seventeenth century shipwreck was examined in order to unravel their condition, manufacturing process and function. This study focuses on the application of non-invasive imaging techniques: optical microscopy, X-radiography, X-ray micro-computed tomography and neutron computed tomography. A valuation of different aspects of the applied techniques was made, aiding stakeholders in decision-making on research and conservation. The combination of theory and scientific information was used to obtain an improved understanding of the manufacturing process and function of the filigree spheres.

A rare find of a high-status 17th century oval box, retrieved from a shipwreck, provided a unique opportunity to research the construction and finishing layers of an object that is untouched for 350 years. This case study was used to demonstrate the extent of data that can be gained from analytical techniques prior to conservation. The amalgam-gilt brass object was studied by optical and electron microscopy, X-radiography, micro-computed X-ray tomography, neutron tomography, X-ray fluorescence, X-ray diffraction, Rutherford backscattering spectrometry, proton-induced X-ray emission and gas chromatography. The results have led to a characterisation of the manufacturing methods used on the box and to a better understanding of the practicality of modern analytical methods and techniques in (maritime) archaeological research.

Iron is a promising, earth-abundant material for future energy applications. In this study, we use a neutron diffractometer to investigate the properties of an iron electrode in an alkaline environment. As neutrons penetrate deeply into materials, neutron scattering gives us a unique insight into what is happening inside the electrode. We made our measurements while the electrode was charging or discharging. Our key questions are: Which phases occur for the first and second discharge plateaus? And why are iron electrodes less responsive at higher discharge rates? We conclude that metallic iron and iron hydroxide form the redox pair for the first discharge plateau. For the second discharge plateau, we found a phase similar to feroxyhyte but with symmetrical and equally spaced arrangement of hydrogen atoms. The data suggest that no other iron oxide or iron (oxy)hydroxide formed. Remarkable findings include the following: (1) substantial amounts of iron hydroxide are always present inside the electrode. (2) Passivation is mostly caused by iron hydroxide that is unable to recharge. (3) Iron fractions change as expected, while iron hydroxide fractions are delayed, resulting in substantial amounts of amorphous, undetectable iron phases. About 40% of the participating iron of the first plateau and about 55% of the participating iron for the second plateau are undetectable. (4) Massive and unexpected precipitation of iron hydroxide occurs in the transition from discharging to charging. (2), (3), and (4) together cause accumulation of iron hydroxide inside the electrode.

The technique of neutron tomography has, after 350 years, enabled a first look inside the iconic single-lens microscopes of Antoni van Leeuwenhoek. Van Leeuwenhoek's 17th-century discovery of "animalcules" marks the birth of microbiology. His skillfully self-produced microscope lenses remained unsurpassed for over 150 years. Neutron tomography now enabled us to reveal the lens types Van Leeuwenhoek used. We argue that Van Leeuwenhoek's instruments incorporate some innovations that testify to an awareness of concurrent developments. In particular, our analysis shows that for making his best-performing microscopes, Van Leeuwenhoek deployed a lens-making procedure popularized in 1678 by Robert Hooke. This is notable, as Hooke always wanted to find the secret of Van Leeuwenhoek's lenses, but never managed to do so. Therefore, Van Leeuwenhoek was far from the isolated scholar he is often claimed to be; rather, his secrecy about his lenses was motivated by an attempt to conceal his indebtedness to Hooke.

Fluid catalytic cracking (FCC) produces (the feedstock for) a major part of the world's fuels, as well as chemical building blocks for, for example, polymers, pharmaceuticals, and specialty materials. ZSM-5 is the active ingredient in propyleneselective FCC catalyst systems and is stabilized or activated with phosphorus compounds. Despite this process being one of the largest-scale industrially applied catalytic processes, there is still considerable debate on the mechanism of activation, as well as on the interaction between phosphate and zeolite aluminum species. In this work, we use synchrotron-based powder XRD, neutron diffraction, and subsequent pair distribution function analysis to unequivocally corroborate the activation mechanism of phosphorus-based promotion in FCC catalysis and localize the phosphate groups inside the pore system of P-activated ZSM-5. We find local disorder in the zeolite T-O coordination, which could not be observed with traditional XRD analyses. Furthermore, we support these experimental findings with full periodic quantum-mechanical modeling (QMM) of the highly relevant, but often overlooked, combination of dealumination by hydrolysis (steaming) and phosphatation of the zeolite framework. We thereby show that phosphate can react with partially dislodged aluminum species that remain stable and are still tethered to their original framework position. Finally, by assessing all available literature postulations by the same periodic QMM and comparing them energetically with our obtained results, we can conclude that by accounting for the highly relevant inclusion of steaming prior to phosphatation, the two models resulting from this work rank among the three most relevant remaining models. This combined experimental and theoretical work fundamentally explains the activation and promotion mechanism of one of the world's most applied chemical processes?propylene-selective FCC.