Plastic from Wood

X-ray analysis points the way to lignin-based components made to measure

The biopolymer lignin is a by-product of papermaking and a promising raw material for manufacturing sustainable plastic materials. However, the quality of this naturally occurring product is not as uniform as that of petroleum-based plastics. An X-ray analysis carried out at DESY reveals for the first time how the internal molecular structure of different lignin products is related to the macroscopic properties of the respective materials. The study, which has been published in the journal Applied Polymer Materials, provides an approach for a systematic understanding of lignin as a raw material to allow for production of lignin-based bioplastics with different properties, depending on the specific application.

Read more on the PETRA III at DESY website (opens in a new tab)”>>Read more on the PETRA III at DESY website

Image: Lignin is a promising raw material (left) for thermoplast (right) production.
Credit: KTH Stockholm, Marcus Jawerth

Water improves material’s ability to capture CO2

With the help of the Advanced Light Source (ALS), researchers from UC Berkeley and ExxonMobil fine-tuned a material to capture CO2 in the presence of water.

About 65% of anthropogenic greenhouse gas emissions comes from the combustion of fossil fuels in power plants. So far, efforts to capture CO2 from power-plant flue gases and sequester it underground have mainly focused on coal-fired power plants. However, in the United States, natural gas has surpassed coal in the amount CO2 released, despite the fact that natural gas emits approximately half as much CO2 per unit of electricity. Therefore, new materials are urgently needed to address this situation.

Not all combustion is alike

Compared to coal-fired power plants, natural gas combined cycle (NGCC) plants produce flue gases with low CO2 concentrations. This reduces the carbon footprint, but increases the technical difficulty of CO2 capture. Also, materials capable of adsorbing such low concentrations of CO2 often require high temperatures to release it for sequestration, an important part of the cycle that offsets initial low-carbon benefits. NGCC emissions also have a higher concentration of O2, which has a corrosive effect on adsorbent materials, and both NGCC and coal flue streams are saturated in water, which can both degrade materials and reduce efficiency. Thus, an effective NGCC CO2-capture material must selectively bind low-concentration CO2 under humid conditions while being thermally and oxidatively stable.

>Read more on the Advanced Light Source website

Image: Single-crystal x-ray diffraction enables the precise determination of the positions of the atoms in metal–organic frameworks (MOFs), highly porous materials capable of soaking up vast quantities of a specific gas molecule, such as CO2. This structure represents 2-ampd–Zn2(dobpdc), a MOF with the same structure as 2-ampd–Mg2(dobpdc), the subject of this study. Light blue, blue, red, gray, and white spheres represent Zn, N, O, C, and H atoms, respectively.

A fast and precise look into fibre-reinforced composites

Researchers at the Paul Scherrer Institute PSI have improved a method for small angle X-ray scattering (SAXS) to such an extent that it can now be used in the development or quality control of novel fibre-reinforced composites.

This means that in the future, such materials can be investigated not only with X-rays from especially powerful sources such as the Swiss Light Source SLS, but also with those from conventional X-ray tubes. The researchers have published their results in the journal Nature Communications.
Novel fibre-reinforced composites are becoming increasingly important as stable and lightweight materials. One example of this type of composite is carbon fibre reinforced polymers (CFRP), which are used in aircraft construction or in the construction of Formula 1 racing cars and sports bicycles. The properties of these materials depend to a large extent on how the tiny fibres are aligned and how they are arranged and embedded in the surrounding material, influencing the mechanical, optical, or electromagnetic behaviour of the composites.

To investigate the fibre’s orientation in such composites, researchers must look inside them. One could use small angle X-ray scattering (SAXS), exploiting the fact that X-rays are scattered when they penetrate matter. The resulting scattering pattern can then be used to obtain information about the interior of a sample and potentially the orientation of the fibres. However, the common SAXS methods have the disadvantage of being quite slow: It can take up to several hours to scan centimetre-sized specimens with the required resolution.

>Read more on the Swiss Light Source (PSI) website

Image: Matias Kagias (left) and Marco Stampanoni in front of the apparatus with which they examined the composites using the newly developed X-ray method. Both hold one of the workpieces that have been X-rayed.
Credit: Paul Scherrer Institute/Mahir Dzambegovic

Dynamic pattern of skyrmions observed

Tiny magnetic vortices known as skyrmions form in certain magnetic materials, such as Cu2OSeO3.

These skyrmions can be controlled by low-level electrical currents – which could facilitate more energy-efficient data processing. Now a team has succeeded in developing a new technique at the VEKMAG station of BESSY II for precisely measuring these vortices and observing their three different predicted characteristic oscillation modes (Eigen modes).

Cu2OSeO3 is a material with unusual magnetic properties. Magnetic spin vortices known as skyrmions are formed within a certain temperature range when in the presence of a small external magnetic field. Currently, moderately low temperatures of around 60 Kelvin (-213 degrees Celsius) are required to stabilise their phase, but it appears possible to shift this temperature range to room temperature. The exciting thing about skyrmions is that they can be set in motion and controlled very easily, thus offering new opportunities to reduce the energy required for data processing.

>Read more on the BESSY II at HZB website

Image: The illustration demonstrates skyrmions in one of their Eigen modes (clockwise).
Credit: Yotta Kippe/HZB

New research possibilities at NanoMAX

X-rays can penetrate materials and are therefore useful for studying chemical processes as they occur inside reactors, cells, and batteries. A common ingredient in such chemical systems is metal nanoparticles, which are often used as catalysts for important reactions. As the NanoMAX beamline provides a very small X-ray focal spot, single nanoparticles can in principle be studied as they perform their catalytic functions.

In this paper, we show that gold nanoparticles sitting inside an electrochemical cell can be imaged at NanoMAX. These preliminary results come from nanoparticles around 60 nm (60 millionths of a millimetre) in size, and we show that even smaller particles could be studied. If successful, future experiments will allow “filming” nanoparticles as they catalyze reactions in real-time, and give new understanding of how catalysis works. That could in turn help design new materials for energy conversion, chemical production, and water purification.

>Read more on the MAX IV Laboratory
Image (extract, full image here): Coherent Bragg imaging of 60 nm Au nanoparticles under electrochemical control at the NanoMAX beamline

Enhancing Materials for Hi-Res Patterning to Advance Microelectronics

Scientists at Brookhaven Lab’s Center for Functional Nanomaterials created “hybrid” organic-inorganic materials for transferring ultrasmall, high-aspect-ratio features into silicon for next-generation electronic devices.

To increase the processing speed and reduce the power consumption of electronic devices, the microelectronics industry continues to push for smaller and smaller feature sizes. Transistors in today’s cell phones are typically 10 nanometers (nm) across—equivalent to about 50 silicon atoms wide—or smaller. Scaling transistors down below these dimensions with higher accuracy requires advanced materials for lithography—the primary technique for printing electrical circuit elements on silicon wafers to manufacture electronic chips. One challenge is developing robust “resists,” or materials that are used as templates for transferring circuit patterns into device-useful substrates such as silicon.

>Read more on the NSLS-II at Brookhaven Lab website

Image: (Left to right) Ashwanth Subramanian, Ming Lu, Kim Kisslinger, Chang-Yong Nam, and Nikhil Tiwale in the Electron Microscopy Facility at Brookhaven Lab’s Center for Functional Nanomaterials. The scientists used scanning electron microscopes to image high-resolution, high-aspect-ratio silicon nanostructures they etched using a “hybrid” organic-inorganic resist.

The role of ‘charge stripes’ in superconducting materials

The studies could lead to a new understanding of how high-temperature superconductors operate.

High-temperature superconductors, which carry electricity with zero resistance at much higher temperatures than conventional superconducting materials, have generated a lot of excitement since their discovery more than 30 years ago because of their potential for revolutionizing technologies such as maglev trains and long-distance power lines. But scientists still don’t understand how they work.
One piece of the puzzle is the fact that charge density waves – static stripes of higher and lower electron density running through a material – have been found in one of the major families of high-temperature superconductors, the copper-based cuprates. But do these charge stripes enhance superconductivity, suppress it or play some other role?
In independent studies, two research teams report important advances in understanding how charge stripes might interact with superconductivity. Both studies were carried out with X-rays at the Department of Energy’s SLAC National Accelerator Laboratory.

>Read more on the LCLS at SLAC website

Image: This cutaway view shows stripes of higher and lower electron density – “charge stripes” – within a copper-based superconducting material. Experiments with SLAC’s X-ray laser directly observed how those stripes fluctuate when hit with a pulse of light, a step toward understanding how they interact with high-temperature superconductivity.
Credit: Greg Stewart/SLAC National Accelerator Laboratory

For superconductors, discovery comes from disorder

Discovered more than 100 years ago, superconductivity continues to captivate scientists who seek to develop components for highly efficient energy transmission, ultrafast electronics or quantum bits for next-generation computation.  However, determining what causes substances to become — or stop being — superconductors remains a central question in finding new candidates for this special class of materials.

In potential superconductors, there may be several ways electrons can arrange themselves. Some of these reinforce the superconducting effect, while others inhibit it. In a new study, scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory have explained the ways in which two such arrangements compete with each other and ultimately affect the temperature at which a material becomes superconducting.

>Read more on the Advanced Photon Source at Argonne National Lab website

Image: This image shows the transition between Cooper pair density (indicated by blue dots) and charge density waves. Argonne scientists found that by introducing defects, they could disrupt charge density waves and increase superconductivity.
Credit:
Ellen Weiss / Argonne National Laboratory

Tuning material properties with laser light

The research results suggest the possibility of creating microelectronic devices that use a laser beam to erase and rewrite bits of information in materials engineered for random-access memory and data storage.

Many semiconductor-based devices use electric currents to control and manipulate bits of information encoded into tiny magnetic domains. However, this approach is reaching the physical limits of thermally stable feature sizes, and scientists are actively searching for the next generation of materials and processes that could lead to smaller, faster, more powerful devices.
One possible path forward has been opened up by the emergence of materials that can be engineered, layer by layer, to theoretical specifications. Multiferroics, for example, are designed materials with technologically useful properties that can be controlled by external fields. While many studies have been performed on the effects of electric and magnetic fields on multiferroics, very few studies have explored the use of optical modulation (i.e., laser light) as a way to tune magnetic and electronic ordering in such materials.

>Read more on the Advanced Light Source at LBL website

Images: They are taken at the same illuminated region using PFM, PEEM with linearly polarized x-rays, and PEEM with circularly polarized x-rays. The strong black and white contrast in the linear dichroism image indicates the antiferromagnetic order; the red/blue contrast in the circular dichroism image shows the existence of ferromagnetic moments that lie parallel/antiparallel to the incident x-rays, respectively.

Weyl fermions discovered in another class of materials

A particular kind of quasi-particle states, the Weyl fermions, were first discovered a few years ago in certain solids. Their specialty: They move through a material in a well ordered manner that practically never lets them collide with each other and is thus very energy efficient. This implies intriguing possibilities for the electronics of the future. Up to now, Weyl fermions had only been found in certain non-magnetic materials. Now however, for the very first time, scientists at the Paul Scherrer Institute PSI have experimentally proven their existence in another type of material: a paramagnet with intrinsic slow magnetic fluctuations. This finding also shows that it is possible to manipulate the Weyl fermions with small magnetic fields. It thus opens further possibilities to use them in spintronics, a promising development in electronics for novel computer technology. The researchers have published their findings in the scientific journal Science Advances.

Amongst the approaches that could pave the way to energy efficient electronics of the future, Weyl fermions could play a role. Found experimentally only inside materials as so-called quasi-particles, they behave like particles which have no mass. Predicted theoretically already in 1929 by the mathematician Hermann Weyl, their experimental discovery by scientists amongst other at PSI only came in 2015. So far, Weyl fermions had only been observed in certain non-magnetic materials. Now however, a team of scientists at PSI together with researchers in the USA, China, Germany and Austria also found them in a specific paramagnetic material. This discovery could bring a potential usage of Weyl fermions in future computer technology one step closer.

>Read more on the Swiss Light Source at PSI website

Image: The three PSI researchers Junzhang Ma, Ming Shi and Jasmin Jandke (from left to right) at the Swiss Light Source SLS, where they succeeded in proving the existence of Weyl fermions in paramagnetic material.
Credit: Paul Scherrer Institute/Markus Fischer

Enhancing solar energy production

Research investigates ways to convert titanium dioxide into a new photoactive material in the visible light range.

The search for clean and renewable energy sources has intensified in recent years due to the increase in atmospheric concentration of greenhouse gases and the consequent increase in the average temperature of the planet. One such alternative source is the conversion of sunlight into electricity through photovoltaic panels. The efficiency in this conversion depends on the intrinsic properties of the materials used in the manufacturing of the panels, and it increases year by year with the discovery of new and better materials. As such, solar energy is expected to become one of the main sources of electric energy by the middle of this century, according to the International Energy Agency (IEA).

Titanium dioxide (TiO2) is an abundant, nontoxic, biologically inert and chemically stable material, known primarily as a white pigment used in paints, cosmetics and even toothpastes. TiO2 is also often used in sunscreens since it is especially capable of absorbing radiation in the ultraviolet region. However, this same property severely limits the use of TiO2 for solar energy conversion, since the ultraviolet emission comprises only 5 to 8% of the total energy of the solar light.

Can this TiO2 property be extended to the visible light region to increase the conversion of sunlight into electricity? To answer this question, Maria Pilar de Lara-Castells et al. [1] conducted an innovative research in which they discuss how a special treatment can change the optical properties of TiO2.

>Read more on the Brazilian Synchrotron Light Laboratory website

How morphing materials store information

Experiments at SLAC’s X-ray laser reveal in atomic detail how two distinct liquid phases in these materials enable fast switching between glassy and crystalline states that represent 0s and 1s in memory devices.

Instead of flash drives, the latest generation of smart phones uses materials that change physical states, or phases, to store and retrieve data faster, in less space and with more energy efficiency. When hit with a pulse of electricity or optical light, these materials switch between glassy and crystalline states that represent the 0s and 1s of the binary code used to store information.
Now scientists have discovered how those phase changes occur on an atomic level.
Researchers from European XFEL and the University of Duisburg-Essen in Germany, working in collaboration with researchers at the Department of Energy’s SLAC National Accelerator Laboratory, led X-ray laser experiments at SLAC that collected more than 10,000 snapshots of phase-change materials transforming from a glassy to a crystalline state in real time.

>Read more on the LCLS at SLAC website

Image: The research team after performing experiments at SLAC’s Linac Coherent Light Source X-ray laser.
Credit: Klaus Sokolowski-Tinten/University of Duisburg-Essen)

Please read also the article published on the EUXFEL website:
Rigid bonds enable new data storage technology

Electric dipoles form chiral skyrmions

Control of such phenomena could one day lead to low-power, nonvolatile data storage as well as to high-performance computers.

A group of researchers, led by scientists from Berkeley Lab’s Materials Sciences Division and UC Berkeley’s Materials Science and Engineering Department, set out to find ways to control how heat moves through materials. They fabricated a material with alternating layers of strontium titanate, which is an electrical insulator, and lead titanate, a ferroelectric material with a natural electrical polarization that can be reversed by the application of an external electric field.

When the group took the material to Berkeley Lab’s Molecular Foundry for atomic-resolution scanning transmission electron microscope (STEM) measurements, however, they found something completely unexpected: bubble-like formations had appeared throughout the material, even at room temperature.

>Read more on the ALS website

Image: (a) Hard x-ray studies showed the presence of two sets of ordering: regular peaks along the out-of-plane direction (Qz), related to superlattice periodicity (about 12 nm), and satellite peaks in the in-plane direction (Qy), corresponding to the in-plane skyrmion periodicity (about 8 nm). (b) RSXD studies were performed at the in-plane satellite peaks, which correspond to the periodic polarization texture of the skyrmions’ Bloch components. (c) Spectra from a satellite peak for right- (red) and left- (blue) circularly polarized light. (d) The same spectra with background fluorescence subtracted. (e) The difference spectrum shows a clear circular dichroism peak at the titanium L3 t2g edge.

New material with magnetic shape memory

Researchers at the Paul Scherrer Institute PSI and ETH Zurich have developed a new material whose shape memory is activated by magnetism.

It retains a given shape when it is put into a magnetic field. It is a composite material consisting of two components. What is special about the new material is that, unlike previous shape-memory materials, it consists of a polymer and droplets of a so-called magnetorheological fluid embedded in it. Areas of application for this new type of composite material include medicine, aerospace, electronics and robotics. The researchers are now publishing their results in the scientific journal Advanced Materials.
It looks like a magic trick: A magnet moves away from a black, twisted band and the band relaxes –without any further effect (see video). What looks like magic can be explained by magnetism. The black ribbon consists of a composite of two components: a silicone-based polymer and small droplets of water and glycerine in which tiny particles of carbonyl iron float. The latter provide the magnetic properties of the material and its shape memory. If the composite material is forced into a certain shape with tweezers and then exposed to a magnetic field, this shape is retained even when the tweezers are removed. Only when the magnetic field is also removed does the material return to its original shape.

>Read more on the Swiss Light Source website

Image: Paolo Testa, first author of the study, with a model of the overall structure of the shape-memory material
Credit: Paul Scherrer Institute/Mahir Dzambegovic

Scientists design organic cathode for high performance batteries

The new, sulfur-based material is more energy-dense, cost-effective, and environmentally friendly than traditional cathodes in lithium batteries.

Researchers at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have designed a new, organic cathode material for lithium batteries. With sulfur at its core, the material is more energy-dense, cost-effective, and environmentally friendly than traditional cathode materials in lithium batteries. The research was published in Advanced Energy Materials on April 10, 2019.

Optimizing cathode materials

From smartphones to electric vehicles, the technologies that have become central to everyday life run on lithium batteries. And as the demand for these products continues to rise, scientists are investigating how to optimize cathode materials to improve the overall performance of lithium battery systems.
“Commercialized lithium-ion batteries are used in small electronic devices; however, to accommodate long driving ranges for electric vehicles, their energy density needs to be higher,” said Zulipiya Shadike, a research associate in Brookhaven’s Chemistry Division and the lead author of the research. “We are trying to develop new battery systems with a high energy density and stable performance.”

>Read more on the NSLS-II website

Image: Lead author Zulipiya Shadike (right) is pictured at NSLS-II’s XPD beamline with lead beamline scientist and co-author Sanjit Ghose (left).

New material also reveals new quasiparticles

Researchers at PSI have investigated a novel crystalline material that exhibits electronic properties that have never been seen before.

It is a crystal of aluminum and platinum atoms arranged in a special way. In the symmetrically repeating unit cells of this crystal, individual atoms were offset from each other in such a way that they – as connected in the mind’s eye – followed the shape of a spiral staircase. This resulted in novel properties of electronic behaviour for the crystal as a whole, including so-called Rarita-Schwinger fermions in its interior and very long and quadruple topological Fermi arcs on its surface. The researchers have now published their results in the journal Nature Physics.

Researchers at the Paul Scherrer Institute PSI have found a new kind of quasiparticle. Quasiparticles are states in material that behave in a certain way like actual elementary particles. The two physicists William Rarita and Julian Schwinger had predicted this type of quasiparticles in 1941, which came to be known as Rarita-Schwinger fermions. Exactly these have now been detected experimentally for the first time – thanks in part to measurements at the Swiss Synchrotron Light Source SLS at PSI. “As far as we know, we are – simultaneously with three other research groups – among the first to see Rarita-Schwinger fermions”, says Niels Schröter, a researcher at PSI and first author of the new study.

>Read more on the Swiss Light Source at PSI website.

Image: Niels Schröter (left) and Vladimir Strocov at their experimental station in the Swiss Light Source SLS at PSI.
Credit: Paul Scherrer Institute/Mahir Dzambegovic