Category: BESSY II at HZB

Environmental Chemistry at BESSY II: Radicals in waterways

Environmental Chemistry at BESSY II: Radicals in waterways

How do radicals form in aqueous solutions when exposed to UV light? This question is important for health research and environmental protection, for example with regard to the overfertilisation of water bodies by intensive agriculture. A team at BESSY II has now developed a new method of investigating hydroxyl radicals in solution. By using a clever trick, the scientists gained surprising insights into the reaction pathway.

Hydroxyl radicals (OH·) are found everywhere, from the troposphere to the cells of the human body. There, they cause oxidative stress and accelerate the ageing process. They are also increasingly present in rivers and lakes, where they are formed by the photolysis of nitrogen oxides that have entered the water from over-fertilised soils. When UV radiation from sunlight strikes nitrogen oxides, hydroxyl radicals and a range of other radicals are generated. The chemistry of these radicals is extremely difficult to characterise accurately, as they react very quickly

A team led by Professor Alexander Föhlisch of the HZB has investigated the chemistry of hydroxyl radicals formed from nitrogen oxides in water using X-ray absorption spectroscopy at the BESSY II X-ray source.

Read more on the HZB website

Image: How the radical scavenger TEMPO traps a hydroxyl radical OH·. The proton of the hydroxyl radical reacts with TEMPO first. Colour coding: grey for C (carbon), white for H (hydrogen), red for O (oxygen) and blue for N (nitrogen)

Credit: © HZB

A duo for BESSY III light source

A duo for BESSY III light source

Since 1 March 2026, Renske van der Veen and Andreas Jankowiak have formed the leadership team of BESSY III. Together, they will drive forward HZB’s central project: the planning and realisation of BESSY III light source in Berlin-Adlershof. Here, they talk about their motivation, the next steps, and why BESSY III is a a cross-generational project.

Dear Renske, dear Andreas, a new chapter for our huge BESSY III project is now beginning with you. What do you bring to the table?

Renske van der Veen: Energy and enthusiasm for the project and also for teamwork! I love working with lots of people to achieve something big. For me, BESSY III is a fantastic opportunity to put all this into practice, and I also bring the necessary pragmatism to the table.

Andreas Jankowiak: I bring 15 years of experience at HZB in various management positions and experience from different committees. For example, I have been chairing the machine advisory committee of Diamond II (successor to Diamond, UK) for six years. This gives me a sense of what is happening around us in this field and how things are developing there. I am also enthusiastic that we are a research centre with our own strong research profile, which benefits greatly from our large-scale facility BESSY. For me, this connection is an absolute added value.

Read more on the HZB website

Image: Renske van der Veen und Andreas Jankowiak take over the scientific and technical projectlead of BESSY III light source

Credit: © HZB / Florentine Krawatzek

MXene for energy storage: More versatile than expected

MXene for energy storage: More versatile than expected

MXene materials are promising candidates for a new energy storage technology. However, the processes by which the charge storage takes place were not yet fully understood. A team at HZB has examined, for the first time, individual MXene flakes to explore these processes in detail. Using the in situ Scanning transmission X-ray microscope ‘MYSTIIC’ at BESSY II, the scientists mapped the chemical states of Titanium atoms on the MXene flake surfaces. The results revealed two distinct redox reactions, depending on the electrolyte. This lays the groundwork for understanding charge transfer processes at the nanoscale and provides a basis for future research aimed at optimising pseudocapacitive energy storage devices.

Energy storage is crucial for achieving a climate-neutral and efficient energy supply, based on renewable energy sources. Current technologies have their pros and cons. Batteries, for example, require a certain amount of time to charge but can store enormous amounts of energy, whereas electric double-layer capacitors (EDLCs) charge quickly but can only absorb a limited amount of energy. So called pseudocapacitors could combine high storage capacity with speed, due to a charge transfer process based on chemical changes without changing the phase of material. Up to now, this technology has not yet been realised due to a lack of promising materials.

The hidden talents of MXenes

This might change with MXene materials. MXenes are two-dimensional materials with a layered structure, such as titanium carbide, which form a conductive core and a highly reactive surface. The distance between layers is in the order of a few nanometers. Via aqueous electrolytes, protons and Li ions can intercalate between MXene layers and act as charge carriers. The charge carriers bind to the surface terminations on the Titanium atoms via redox reactions. Another advantage: Aqueous electrolytes are generally much more environmentally friendly than organic electrolytes used in batteries.

Read more on the HZB website

Image: In a neutral electrolyte Li2SO4 the interaction of partially desolvated Li⁺ ions and water with the MXene surface results in an increased Titanium oxidation state. The two different chemical behaviours also change the interlayer spacing of the flakes.

Credit: © Energy & Environmental Science / HZB

Synchrotron radiation sources: toolboxes for quantum technologies

Synchrotron radiation sources: toolboxes for quantum technologies

Synchrotron radiation sources generate highly brilliant light pulses, ranging from infrared to hard X-rays, which can be used to gain deep insights into complex materials. An international team has now published an overview on synchrotron methods for the further development of quantum materials and technologies in the journal Advanced Functional Materials: Using concrete examples, they show how these unique tools can help to unlock the potential of quantum technologies such as quantum computing, overcome production barriers and pave the way for future breakthroughs.

In quantum technologies, quantum physical principles such as superposition, interference and entanglement play a decisive role in their function. Components in quantum technology can perform calculations orders of magnitude more efficiently and encrypt information (quantum computing) or deliver unprecedented measurement accuracy in sensors. However, developing such components for practical use remains challenging because quantum systems are inherently sensitive to environmental disturbances, making precise control under normal conditions difficult. To make progress in this area and identify sources of error, it is essential that the materials and devices are thoroughly characterised and better understood.

Read more on the HZB website

Image: A special look at the BESSY II experimental hall

Credit: © Volker Mai/HZB

The future of corals – what X-rays can tell us

The future of corals – what X-rays can tell us

This summer, it was all over the media. Driven by the climate crisis, the oceans have now also passed a critical point, the absorption of CO2 is making the oceans increasingly acidic. The shells of certain sea snails are already showing the first signs of damage. But also the skeleton structures of coral reefs are deteriorating in more acidic conditions. This is especially concerning given that corals are already suffering from marine heatwaves and pollution, which are leading to bleaching and finally to the death of entire reefs worldwide. But how exactly does ocean acidification affect reef structures?

Prof. Dr. Tali Mass, a marine biologist from the University of Haifa, Israel, is an expert on stony corals. Together with Prof. Dr. Paul Zaslansky, X-ray imaging expert from Charité Berlin, she investigated at BESSY II the skeleton formation in baby corals, raised under different pH conditions. Antonia Rötger spoke online with the two experts about the results of their recent study and the future of coral reefs.

What types of corals did you examine?

Tali Mass: These are coral larvae from colonies of the stony coral Stylophora pistillata from the Red Sea. We collected them ourselves during spawning nights in April 2020 at a depth of a few metres. They come from the reef next to the Interuniversity Institute of Marine Sciences in the Gulf of Eilat, Israel. We allowed these larvae to grow in our environment simulators aquaria system for several weeks and exposed them to different pH-conditions. Some tanks contained normal seawater, while others replicated conditions that simulated acidity predicted at the end of this century, assuming no climate protection measures are taken worldwide. This scenario, known as RCP8.5, is associated with significant acidification and global temperature increase of four degrees or more, expected to cause major global disruption. In this context, corals are giving us a window into a potential, bleak future.

Read more on the HZB website

Image: Stony corals in the Red Sea are rich ecosystems, hosting various fish and other marine organisms. The reef is formed by countless coral animals (polyps). The corals live symbiotically with certain algae, which give them their vibrant colour

Credit: © Tali Mass

Phosphorous chains – a 1D material with 1D electronic properties

Phosphorous chains – a 1D material with 1D electronic properties

For the first time, a team at BESSY II has succeeded in demonstrating the one-dimensional electronic properties of a material through a highly refined experimental process. The samples consisted of short chains of phosphorus atoms that self-organise at specific angles on a silver substrate. Through sophisticated analysis, the team was able to disentangle the contributions of these differently aligned chains. This revealed that the electronic properties of each chain are indeed one-dimensional. Calculations predict an exciting phase transition to be expected as soon as these chains are more closely packed. While material consisting of individual chains with longer distances is semiconducting, a very dense chain structure would be metallic.

The material world consists of atoms that combine to manifold different substances. As a rule, atoms bond with each other both in one plane and perpendicular to it. However, some atoms such as carbon can also form graphene, a two dimensional (2D) hexagonal network in which they are connected only in one plane. Also, the element phosphorus can form stable 2D networks. 2D materials are an exciting area of research due to their amazing electronic and optical properties. Theoretical considerations suggest that the electro-optical properties of one-dimensional structures could be even more extraordinary.

Read more on the HZB website

Image: The image taken with the scanning tunnelling microscope shows the phosphorus atoms arranged in short chains on a silver substrate.

Credit: © HZB/Small Structures (2025)/10.1002/sstr.202500458

Metallic nanocatalysts: what really happens during catalysis

Metallic nanocatalysts: what really happens during catalysis

Using a combination of spectromicroscopy at BESSY II and microscopic analyses at DESY’s NanoLab, a team has gained new insights into the chemical behaviour of nanocatalysts during catalysis. The nanoparticles consisted of a platinum core with a rhodium shell. This configuration allows a better understanding of structural changes in, for example, rhodium-platinum catalysts for emission control. The results show that under typical catalytic conditions, some of the rhodium in the shell can diffuse into the interior of the nanoparticles. However, most of it remains on the surface and oxidises. This process is strongly dependent on the surface orientation of the nanoparticle facets.

Nanoparticles measure less than one ten-thousandth of a millimetre in diameter and have enormous surface areas in relation to their mass. This makes them attractive as catalysts: metallic nanoparticles can facilitate chemical conversions, whether for environmental protection, industrial synthesis or the production of (sustainable) fuels from CO2 and hydrogen.

Platinum core with Rhodium shell

Platinum (Pt) is one of the best-known metal catalysts and is used in heterogeneous gas phase catalysis for emission control, for example to convert toxic carbon monoxide in car exhaust gases from combustion engines into non-toxic CO2. ‘Mixing platinum particles with the element rhodium (Rh) can further increase efficiency,’ says Jagrati Dwivedi, first author of the publication. The location of the two elements plays an important role in this process. So-called core-shell nanoparticles with a platinum core and an extremely thin rhodium shell can help in the search for the optimal element distribution that can extend the lifetime of the nanoparticles.

Experiments at BESSY II and DESY NanoLab

Until now, however, little was known about how the chemical composition of a catalyst’s surface changes during operation. A team led by Dr Thomas F. Keller, head of the microscopy group at DESY NanoLab, has now investigated such crystalline Pt-Rh nanoparticles at BESSY II and gained new insights into the changes at the facets of the polyhedral nanoparticles.

The nanoparticles were first characterised and marked in their vicinity using scanning electron microscopy and atomic force microscopy at DESY NanoLab. These markers were then used to analyse the same nanoparticles spectroscopically and image them microscopically simultaneously using X-ray light on a special instrument at BESSY II.

The SMART instrument at the Fritz Haber Institute of the Max Planck Society enables X-ray photoemission electron microscopy (XPEEM) in a microscope mode. This makes it possible to distinguish individual elements with high spatial resolution, enabling the observation of chemical processes at near-surface atomic layers. ‘The instrument allows the chemical analysis of individual elements with a resolution of 5-10 nanometres, which is unique,’ says Thomas Keller. The investigation has shown that rhodium can partially diffuse into the platinum cores during catalysis: both elements are miscible at the typical operating temperatures of the catalyst. The mixing is enhanced in a reducing environment (H2) and slowed down in an oxidising environment (O2) without reversing the net flow of rhodium into platinum. ‘At higher temperatures, this process even increases significantly,’ explains Keller.

Read more on BESSY II website

Scrolls from Buddhist shrine virtually unrolled at BESSY II

Scrolls from Buddhist shrine virtually unrolled at BESSY II

The Mongolian collection of the Ethnological Museum of the National Museums in Berlin contains a unique Gungervaa shrine. Among the objects found inside were three tiny scrolls, wrapped in silk. Using 3D X-ray tomography, a team at HZB was able to create a digital copy of one of the scrolls. With a mathematical method the scroll could be virtually unrolled to reveal the scripture on the strip. This method is also used in battery research.

Buddhism in Mongolia has developed its own traditions that are linked to nomadic culture. Many families had a small portable shrine that they took with them wherever they went. As well as statues, images and decorative objects, these shrines sometimes contained relics and small, tightly rolled scrolls inscribed with prayers, known as ‘dharanis’. During the revolutionary period from 1921 to 1930, this cultural practice was almost completely eradicated with many shrines being destroyed.

However, one of these shrines ended up in Germany, where it was stored in the Ethnological Museum’s archives. Little was known about its origins. When Birgit Kantzenbach, a restorer at the Ethnological Museum, began researching the shrine a few years ago, she found that nothing was in its place; fabric flowers, relics, small statues and three small scrolls lay in a jumble. She first travelled to Mongolia. ‘An object always means only what people see in it; that’s what’s important,’ she says. She then turned to HZB physicist Tobias Arlt to examine the small scrolls wrapped in silk.

Non destructive investigation at BESSY II

Until a few years ago, such scrolls would simply have been unwrapped and unrolled to check for inscriptions However, this carries the risk of damaging the material and causing irreversible changes. Tobias Arlt examined the Dharani scrolls at the tomography station of the Federal Institute for Materials Research and Testing (BAM) at BESSY II. ‘The high-resolution 3D images show that there are around 50 windings in each scroll, with strips measuring over 80 centimetres that are wound tightly and carefully,’ says Arlt.

Virtual unrolling

Using a mathematical method developed at the Konrad Zuse Institute and the corresponding Amira software, he was able to virtually unroll the strip from the 3D data of the rolled sample. Originally, this process took a long time to complete, but with the help of artificial intelligence, it is now considerably faster. ‘We are continuing to optimise this complex process of virtual unrolling,’ says Arlt. ‘We also use this method in our own research, for example to analyse changes in tightly wound or folded batteries.’

Read more on HZB website

Image: The scroll was examined at the BAMline at BESSY II and virtually unrolled. The unrolled strip is slightly longer than 80 cm. ‘Om mani padme hum’ appears on the unrolled strip.

Credit: DOI: 10.1016/j.culher.2025.06.009

Hydrogen storage in MXene: It all depends on diffusion processes

Hydrogen storage in MXene: It all depends on diffusion processes

Two-dimensional (2D) materials such as MXene are of great interest for hydrogen storage. An expert from HZB has investigated the diffusion of hydrogen in MXene using density functional theory. This modelling provides valuable insights into the key diffusion mechanisms and hydrogen’s interaction with Ti₃C₂ MXene, offering a solid foundation for further experimental research.

Hydrogen is an energy carrier that can be produced in a climate-friendly way by electrolysis of water using ‘green’ electricity. However, storing hydrogen is not that easy. MXene could be a promising solution. MXene are compounds of metal and nitrogen or carbon that form a two-dimensional hexagonal structure, giving them special physical and chemical properties. Atoms and molecules, such as hydrogen, can be stored both in and between the 2D layers. ‘However, we know that hydrogen atoms and even molecules form complex bonds in MXene and on its surfaces,’ says Prof. Dr. Norbert Nickel, a physicist at HZB. When storing hydrogen, it is also important that the hydrogen bound in the material can be released when needed.

Previous neutron scattering experiments have shown that hydrogen can be stored in the MXene material Ti3C2. However, in 2024, Nickel calculated exactly how the hydrogen orbitals interact with the titanium and carbon orbitals using density functional theory. These results shed light on the nature of hydrogen’s chemical bonding and how temperature affects the diffusion process (see Annalen der Physik, 536, 2400011 (2024)). Nevertheless, quantum mechanical calculations of the interactions between hydrogen atoms and molecules with Ti₃C₂ show that the simple model of chemical bonding is insufficient to describe hydrogen’s bonding properties.

Recently Nickel analysed the chemical orbitals in more detail: the calculations showed that interstitial hydrogen atoms and molecules form s-like bonds with neighbouring titanium atoms and s-p hybrid orbitals with neighbouring carbon atoms.

Read more on HZB website

Image: Schematic representation of the Ti3C2 crystal lattice with hydrogen and the associated bonding orbitals. Left: normal to the c-axis; right: perpendicular to the c-axis.

Credit: N. Nickel / HZB

MAX IV and BESSY II initiate new collaboration to advance materials science

MAX IV and BESSY II initiate new collaboration to advance materials science

Swedish national synchrotron laboratory MAX IV and Helmholtz-Zentrum Berlin (HZB) BESSY II light source announce the signing of a 5-year Memorandum of Understanding (MoU). The new MoU establishes a framework to strengthen cooperation for operational and technological development in the highlighted fields of accelerator research and development, beamlines and optics, endstations and sample environments as well as digitalisation and data science.

The new agreement increases accessibility and overall opportunities for users to conduct advanced materials science investigations at MAX IV and BESSY II in a smooth, integrated manner. Facility collaboration through project-based initiatives may include, among others, reciprocal exchange of knowledge, instrumentation development and usage, data handling, scientific and technical staff, research initiatives, and PhD programme activities.

“Decades of collaboration between Sweden and HZB—rooted in, for example, shared work on energy-relevant materials and enabling methods and technologies—have continually advanced our field. The MoU we sign today gives MAX IV and HZB a solid platform to keep advancing synchrotron science into the 2030s and beyond,” says Olof Karis, Director of MAX IV.

Read more on MAX IV website

Image: MAX IV and HZB after signing the MoU. From left Olof Karis, Director at MAX IV, Antje Hasselberg, authorized signatory at HZB and Bernd Rech, Scientific Director at HZB.

Credit: HZB / Ronja Gründke

BESSY II: Insight into ultrafast spin processes with femtoslicing

BESSY II: Insight into ultrafast spin processes with femtoslicing

An international team has succeeded at BESSY II for the first time to elucidate how ultrafast spin-polarised current pulses can be characterised by measuring the ultrafast demagnetisation in a magnetic layer system within the first hundreds of femtoseconds. The findings are useful for the development of spintronic devices that enable faster and more energy-efficient information processing and storage. The collaboration involved teams from the University of Strasbourg, HZB, Uppsala University and several other universities.

Spintronic components are not based on moving charges, but on changes in the orientation of magnetic moments, such as electron spins. Spin-current-based devices can therefore operate extremely quickly, currently on time scales of up to one hundred picoseconds (one picosecond is 10-12 s). However, the microscopic processes themselves run much faster, in the range of a few hundred femtoseconds (1 fs = 10-15 s).

Magnetic layers form a spin valve

Now, an international team led by Prof. Christine Boeglin, University of Strasbourg, has been able to experimentally observe some of these particularly interesting dynamic processes in a magnetic layer system for the first time. They investigated a so-called spin valve consisting of alternating layers of platinum-cobalt and an iron-gadolinium alloy layer. In this system, interactions between excited (hot) electrons and magnetic layers are particularly strong. First author Deeksha Gupta and her colleagues conducted the experiments at the femtoslicing station at BESSY II together with the HZB team that is operating this worldwide unique infrastructure.

With a femtosecond infrared laser (IR), they generated hot electrons (HE) in a platinum (Pt) top layer. A thick copper layer (Cu, 60 nm) ensures that only HE pulses reach the Co/Pt layer at the front of the spin valve, which acted as a spin polariser, generating spin-polarised HE pulses (SPHE).

Read more on HZB website

Image: The scheme shows (from left to right): Hot electrons generated by a laser in platinum (light blue), the copper (yellow) is used to block the laser pulse so that only the hot electrons propagate and transport a spin current through the magnetic spin valve structure of cobalt platinum (blue-brown) and iron gadolinium (green).

Credit: D. Gupta /HZB

Battery research: visualisation of aging processes operando

Battery research: visualisation of aging processes operando

Lithium button cells with electrodes made of nickel-manganese-cobalt oxides (NMC) are very powerful. Unfortunately, their capacity decreases over time. Now, for the first time, a team has used a non-destructive method to observe how the elemental composition of the individual layers in a button cell changes during charging cycles. The study, now published in the journal Small, involved teams from the Physikalisch-Technische Bundesanstalt (PTB), the University of Münster, researchers from the SyncLab research group at HZB and the BLiX laboratory at the Technical University of Berlin. Measurements were carried out in the BLiX laboratory and at the BESSY II synchrotron radiation source.

Lithium-ion batteries have become increasingly better. The combination of layered nickel-manganese-cobalt oxides (NMC) with a graphite electrode (anode) has been well established as the cathode material in button cells and has been continuously improved. However, even the best batteries do not last forever; they ‘age’ and lose capacity over time.

‘A lot happens at the interfaces between the anode, separator and cathode while a battery is charging or discharging,’ explains Ioanna Mantouvalou, physicist at HZB and first author of the study. Typically, these changes are only studied after the battery has been disassembled, i.e. ex situ and at a specific point in the cycling process. But there is now another way: in situ and operando experiments allow to look inside the battery while the processes are taking place, using X-ray fluorescence (XRF) and X-ray absorption spectroscopy (XAS) in a so-called confocal geometry. This geometry permits 3D scanning of a sample with depth resolutions down to 10 µm. Such experimental setups are already possible at the synchrotron radiation source BESSY II. However, the measurement time at BESSY II is limited, so batteries cannot be studied over their entire lifetime.

Read more on HZB website

Image: Here is a selection of 3D element distributions of individual elements after 10,000 charge cycles, i.e. post mortem: On the top left, crystallised electrolyte can be seen, iron in the metal contacts and copper from the back contact have remained stable, while manganese from the NMC cathode (upper light blue stripe) has partially deposited on the bottom of the anode. The publication contains the full explanation.

Credit: BLiX/TU Berlin/HZB

Green hydrogen: A cage structured material transforms into a performant catalyst

Green hydrogen: A cage structured material transforms into a performant catalyst

Clathrates are characterised by a complex cage structure that provides space for guest ions too. Now, for the first time, a team has investigated the suitability of clathrates as catalysts for electrolytic hydrogen production with impressive results: the clathrate sample was even more efficient and robust than currently used nickel-based catalysts. They also found a reason for this enhanced performance. Measurements at BESSY II showed that the clathrates undergo structural changes during the catalytic reaction: the three-dimensional cage structure decays into ultra-thin nanosheets that allow maximum contact with active catalytic centres. The study has been published in the journal ‘Angewandte Chemie’.

Hydrogen can be produced by electrolysis of water. If the electrical energy required for this process comes from renewable sources, this hydrogen is even carbon neutral. This ‘green’ hydrogen is seen as an important building block for the energy system of the future and is also needed in large quantities as a raw material for the chemical industry. Two reactions are crucial in electrolysis: hydrogen evolution at the cathode and oxygen evolution at the anode (OER). However, the oxygen evolution reaction in particular slows down the desired process. To speed up hydrogen production, more efficient and robust catalysts for the OER process need to be developed.

Clathrates, a structure build of cages

Currently, nickel-based compounds are considered to be good and inexpensive catalysts for the alkaline oxygen evolution reaction. This is where Dr. Prashanth Menezes and his team come in. ‘The contact between the active nickel centres and the electrolyte plays a crucial role in the efficiency of a catalyst,’ says the chemist. In conventional nickel compounds, this surface area is limited. ‘We therefore wanted to test whether nickel-containing samples from the fascinating class of materials known as clathrates could be used as catalysts’.

The materials are made of Ba8Ni6Ge40 and were produced at the Technical University of Munich. Like all clathrates, they are characterised by a complex crystalline structure of polyhedral cages, in this case, formed by germanium and nickel, enclosing barium. This structure gives clathrates special properties that make them interesting as thermoelectrics, superconductors or battery electrodes. However, until now, no research group had considered of investigating clathrates as electrocatalysts.

Read more on HZB website

Image: The illustration shows schematically how nanothin sheets of nickel compounds are released from the clathrate structure, providing an extremely large surface area for the oxygen evolution reaction. 

Credit: Hongyuan Yang/HZB/TUB

Catalysis research with the X-ray microscope at BESSY II

Catalysis research with the X-ray microscope at BESSY II

Contrary to what we learned at school, some catalysts do change during the reaction: for example, certain electrocatalysts can change their structure and composition during the reaction when an electric field is applied. The X-ray microscope TXM at BESSY II in Berlin is a unique tool for studying such changes in detail. The results help to develop innovative catalysts for a wide range of applications. One example was recently published in Nature Materials. It involved the synthesis of ammonia from waste nitrates.

Ammonia (NH3) is a basic component of fertilisers and is critical to agricultural productivity around the world. Until now, ammonia has been synthesised industrially using the Haber-Bosch process, which is energy intensive and produces significant amounts of greenhouse gases that drive climate change. With the development of alternative methods, ammonia could be produced with significantly lower greenhouse gas emissions.

Better catalysts reduce emissions for Ammonia production

There are some promising approaches. For example, a team at the Fritz Haber Institute has been investigating a catalyst based on nanocrystalline copper oxide. During the catalytic reaction, an increasing proportion of these nanocrystals transformed into metallic particles of pure copper. The morphological changes were documented under the transmission electron microscope (TEM), but to gain insights into the chemical processes during the reaction, the FHI team collaborated with the group of Prof. Gerd Schneider at HZB.

Read more on HZB website

BESSY II: Magnetic ‘microflowers’ enhance local magnetic fields

BESSY II: Magnetic ‘microflowers’ enhance local magnetic fields

A flower-shaped structure only a few micrometres in size made of a nickel-iron alloy can concentrate and locally enhance magnetic fields. The size of the effect can be controlled by varying the geometry and number of ‘petals’. This magnetic metamaterial developed by Dr Anna Palau’s group at the Institut de Ciencia de Materials de Barcelona (ICMAB) in collaboration with her partners of the CHIST-ERA MetaMagIC project, has now been studied at BESSY II in collaboration with Dr Sergio Valencia. Such a device can be used to increase the sensitivity of magnetic sensors, to reduce the energy required for creating local magnetic fields, but also, at the PEEM experimental station, to study samples under much higher magnetic fields than currently possible.

Dr Anna Palau from the Institut de Ciencia de Materials de Barcelona (ICMAB) has developed a special metamaterial that looks like tiny flowers under the scanning electron microscope. The ‘petals’ consist of strips of a ferromagnetic nickel-iron alloy. The microflowers can be produced in various geometries, not only with different inner and outer radii, but also with variable numbers and widths of petals. This flower-shaped geometry causes the field lines of an external magnetic field to concentrate in the centre of the device, resulting on a greatly intensified magnetic field.

Magnetic metamaterials

‘Metamaterials are artificially produced materials with microstructures whose dimensions are smaller than the electromagnetic or thermal waves they are designed to manipulate,’ explains Anna Palau. The physicist is working on magnetic microstructures that can be used in data storage, information processing, biomedicine, catalysis and magnetic sensor technology. By using these metamaterials, the sensitivity of magnetic sensors could be highly increased, as the magnetic field to be detected would be amplified at the center of these systems.

Read more on HZB website

Image: The magnetic microstructure of the nickel-iron alloy leads to a compression of the field lines in the centre.

Credit: A. Palau/ICMAB

New material for efficient separation of Deuterium at elevated Temperatures

New material for efficient separation of Deuterium at elevated Temperatures

A novel porous material capable of separating deuterium (D2) from hydrogen (H2) at a temperature of 120 K has been introduced. Notably, this temperature exceeds the liquefaction point of natural gas, thus facilitating large-scale industrial applications. This advancement presents an attractive pathway for the economical production of D2 by leveraging the existing infrastructure of liquefied natural gas (LNG) production pipelines. The research conducted by Ulsan National Institute of Science & Technology (UNIST), Korea, Helmholtz-Zentrum Berlin, Heinz Maier Leibnitz Zentrum (MLZ), and Soongsil University, Korea, has been published in Nature Communications.

Deuterium, a stable isotope of hydrogen, plays a critical role in enhancing the durability and luminous efficiency of semiconductors and display devices, as well as serving as a fusion fuel in energy production. However, the increasing demand for D2 presents challenges in its production, primarily due to the need to separate from hydrogen through a cryogenic distillation process conducted at temperatures as low as 20 K (-253°C). While research has explored the use of metal-organic frameworks (MOFs) for D2 separation, their efficiency diminishes significantly at elevated temperatures.

In this study, the research team presented a copper-based zeolite imidazolate framework (Cu-ZIF-gis), which shows exceptional D2 separation performance, even at 120 K (-153℃). While typical MOFs operate effectively at around 23 K (-250℃), their performance decreases sharply as temperatures approach 77 K (-196℃). However, the newly developed Cu-based MOF demonstrates a significant advantage in maintaining its effectiveness at higher temperatures.

For the first time, the research team identified that the superior performance of this material results from the increased expansion of its lattice as the temperature rises. At cryogenic temperatures, the pores of the developed MOF are smaller than H2 molecules, thereby inhibiting their passage. However, as the temperature increases, the lattice expands, leading to an increase in pore size. This enlargement facilitates the passage of gases through the pores, thereby enabling the separation of H2 and D2 via the quantum sieving effect, wherein heavier molecules traverse the pores more efficiently at lower temperatures.

Confirmatory in-situ X-ray diffraction (XRD) and quasi-elastic neutron scattering (QENS) experiments, conducted at the Institut Laue-Langevin (ILL) in Grenoble, France, by the joint team from UNIST, HZB and MLZ, confirmed the expansion of the lattice framework with increasing temperature, as well as the difference in isotope diffusivity even at elevated temperatures. Additionally, the analysis from the Thermal Desorption Spectroscopy (TDS) experiments indicated stable D2 separation at elevated temperatures.

Read more on HZB website

Image: The crystal structure of Cu-ZIF-gis that shows cylindrical straight channels along the c-axis. The pores were calculated with Connolly surfaces with a probe of 1.1 Å. (Cu, orange; N, blue; C, gray; O, magenta; H, white).

Credit: Minji Jung / Department of Chemistry, UNIST