Tag: nanoscale

Unique biomaterial found in a lizard

Unique biomaterial found in a lizard

Researchers have found a biomaterial with surprising features in the skin of a lizard. The material is hard like enamel but is structured differently. Understanding the material on the nanoscale opens up new routes in designing for hard-wearing applications.

The Mexican beaded lizard has little hard plates in its skin called osteoderms, which are made of bone and topped with a so-called capping tissue. The plates protect the lizard from being hurt when bitten, but are also unique from a materials standpoint. An international research team has used the beamline DanMAX to study the material in the plates, particularly the capping tissue. 

“We chose this particular lizard because previous work suggested it had a very stiff capping tissue. There are several open questions, such as how such a stiff tissue can form on top of bone and what the structure and mechanics of the capping material are,” says Henrik Birkedal, one of the contributors to the study.

The experiments show that the capping tissue is as hard as enamel. However, its internal structure is different. So, it looks like these types of hard materials could be realised in more than one way, and due to the variability in structure, potentially with different other mechanical properties besides the hardness.  

“One of the most important results of the study was realising that nature fabricates hard mineralised tissues in a way that we had not seen before,” says Birkedal.

Researchers often study nature to understand and ultimately copy the materials created by evolution and natural selection. The research is called biomimicry or bioinspiration.

Read more on MAX IV website

Mapping the Nanoscale Architecture of Functional Materials

Mapping the Nanoscale Architecture of Functional Materials

At the Swiss Light Source SLS, researchers have developed a pioneering X-ray technique to probe the 3D orientation of a material’s building blocks at the nanoscale. Applied to a polycrystalline catalyst, the technique allows the visualisation of crystal grains, grain boundaries and defects – key factors dictating catalyst performance. Beyond catalysis, the innovation unlocks previously inaccessible details about the structure of diverse functional materials, including those used in information technology, energy storage and biomedical applications. The findings are reported in Nature. 

Zoom in to the micro or nanostructure of functional materials, both natural and manmade, and you’ll find they consist of thousands upon thousands of coherent domains or grains – distinct regions where molecules and atoms are arranged in a repeating pattern. 

Such local ordering is inextricably linked to the material properties. The size, orientation, and distribution of grains can make the difference between a sturdy brick or a crumbling stone; it determines the ductility of metal, the efficiency of electron transfer in a semiconductor, or the thermal conductivity of ceramics. It is also an important feature of biological materials: collagen fibres, for example, are formed from a network of fibrils and their organisation determines the biomechanical performance of connective tissue. 

These domains are often tiny: tens of nanometres in size. And it is their arrangement in three-dimensions over extended volumes that is property-determining. Yet until now, techniques to probe the organisation of materials at the nanoscale have largely been confined to two-dimensions or are destructive in nature. 

Now, using X-rays generated by the Swiss Light Source SLS, a collaborative team of researchers from Paul Scherrer Institute PSI, ETH Zurich, the University of Oxford and the Max Plank Institute for Chemical Physics of Solids have succeeded in creating an imaging technique to access this information in three-dimensions.

Read more on PSI website

Image: Many functional materials are composed of coherent domains or grains, where molecules and atoms are arranged in a repeating pattern that determines performance. X-ray Linear Dichroic Orientation Tomography (XL-DOT) allows 3D mapping of material microstructure at the nanoscale. Here, the technique is applied to a pillar of vanadium pentoxide catalyst, used in the production of sulfuric acid. The colours in the tomogram represent the different orientation of grains.

Credit: Paul Scherrer Institute PSI/Andreas Apseros

Superhard Materials at the Nanoscale: Smaller is Better

Superhard Materials at the Nanoscale: Smaller is Better

Scientific Achievement

Using high-pressure radial x-ray diffraction at the Advanced Light Source (ALS), researchers found that in the superhard material, rhenium diboride, smaller grain size leads to greater yield strength (i.e., the amount of stress tolerated before permanent deformation).

The cutting edge

As we get better at making robust, durable materials that resist wear, corrosion, and extreme temperatures—think aerospace, automotive, and industrial machining applications—we also need to step up the quality of the tools we use to cut, form, and polish these hardened materials. Researchers have found that transition-metal borides are promising in this regard because of their low costs and advantageous mechanical properties. Metal borides combine highly incompressible transition metals (e.g., tungsten, rhenium, and osmium) with boron, which readily forms strong covalent bonds—a key characteristic of the prototypical superhard material, diamond. In this work, researchers used radial x-ray diffraction at high pressures to gain insight into how grain size affects the nanoscale deformation mechanics of the superhard material, rhenium diboride (ReB2).

Inspired by diamonds

Diamond is a well-known superhard material. But diamond production requires both high temperatures and high pressures, both of which naturally occur deep underground. To replicate the hardness of diamond under ambient conditions, researchers have looked for materials that incorporate two diamond-like characteristics: densely packed electrons and a highly covalent bonding network.

Electron-dense, incompressible elements can be found toward the bottom of the periodic table, but those elements are also metals, characterized by malleability and ductility. A promising strategy is to combine the metals with boron, which readily forms strong covalent bonds. The first example of a superhard metal boride following this design principle was ReB2, consisting of alternating layers of rhenium and boron. While size-induced hardening has been previously studied in softer inorganic materials, size effects in hard materials have been relatively unexplored.

High-pressure radial x-ray diffraction

In this work, the researchers synthesized ReB2 powder samples with grain sizes of 20, 50, and 60 nm. They then used high-pressure radial x-ray diffraction at ALS Beamline 12.2.2—a dedicated high-pressure beamline—to explore the effect of grain size on yield strength, which is directly related to hardness.

Read more on ALS website

Image: Schematic of radial x-ray diffraction under high pressure. A rhenium diboride (ReB2) powder sample is compressed uniaxially, creating differential compressive stresses that provide insight into the strength, deformation mechanisms, and elasticity of the material.

Shedding Light on Sea Creatures’ Secrets

Shedding Light on Sea Creatures’ Secrets

A nanoscale look at how shells and coral form revealed a mineral that, until now, had never been seen in living organisms – and indicates that biomineralization is more complex than we imagined.

Exactly how does coral make its skeleton, a sea urchin grow a spine, or an abalone form the mother-of-pearl in its shell? A new study at the Advanced Light Source at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) revealed that this process of biomineralization, which sea creatures use to lock carbon away in their bodies, is more complex and diverse than previously thought.

Researchers studied the edges of samples from coral, sea urchin, and mollusks, where temporary building blocks known as “mineral precursors” start to form the new shell or skeleton. There, they found a surprise: Corals and mollusks produced a mineral precursor that had never been observed before in living organisms, and had only recently been created synthetically.

They also found variety in the types of building blocks present. Scientists expected to see “amorphous” precursors, minerals that lack a repeating atomic structure. They did – but they also found “crystalline” precursors, minerals that are more structured and orderly. The research is published in the journal Nature Communications.

Read more on the ALS website

Credit: LazingBee/iStock

Laura Heyderman elected Royal Society Fellow

Laura Heyderman elected Royal Society Fellow

Today, the announcement was made that Laura Heyderman, who leads the Mesoscopic Systems Group at PSI, has been elected Fellow of the Royal Society (FRS). Laura’s nomination recognises almost 30 years of research into magnetic materials and magnetism on the nanoscale, most notably, in the field of artificial spin ice.

Laura Heyderman is best known for her breakthroughs with nanomagnets – minute bar magnets that are a few hundreds of times smaller than the width of a human hair. Her research group, shared between Paul Scherrer Institute PSI and ETH Zurich where she became full professor in 2013, use these to create elaborate structures and devices. With the help of the large research infrastructures at PSI (X-rays, muons and neutrons) they then investigate the novel phenomena that they exhibit. The tiny magnetic systems they create can have a range of technological applications, such as for computation, communication, sensors or actuators.

Read more on the PSI website

Image: Laura Heyderman began working on magnetism as a PhD student investigating magnetic thin films in Paris in 1988. Today, she leads the Mesoscopic Systems Group, shared between PSI and ETH where she is a full professor.

Credit: ETH Zurich / Giulia Marthaler

Magnetic vortices come full circle

Magnetic vortices come full circle

The first experimental observation of three-dimensional magnetic ‘vortex rings’ provides fundamental insight into intricate nanoscale structures inside bulk magnets, and offers fresh perspectives for magnetic devices.

Magnets often harbour hidden beauty. Take a simple fridge magnet: Somewhat counterintuitively, it is ‘sticky’ on one side but not the other. The secret lies in the way the magnetisation is arranged in a well-defined pattern within the material. More intricate magnetization textures are at the heart of many modern technologies, such as hard disk drives. Now, an international team of scientists at PSI, ETH Zurich, the University of Cambridge (UK), the Donetsk Institute for Physics and Engineering (Ukraine) and the Institute for Numerical Mathematics RAS in Moscow (Russia) report the discovery of unexpected magnetic structures inside a tiny pillar made of the magnetic material GdCo2. As they write in a paper published today in the journal Nature Physics [1], the researchers observed sub-micrometre loop-shaped configurations, which they identified as magnetic vortex rings. Far beyond their aesthetic appeal, these textures might point the way to further complex three-dimensional structures arising in the bulk of magnets, and could one day form the basis for novel technological applications.

Mesmerising insights

Determining the magnetisation arrangement within a magnet is extraordinarily challenging, in particular for structures at the micro- and nanoscale, for which studies have been typically limited to looking at a shallow layer just below the surface. That changed in 2017 when researchers at PSI and ETH Zurich introduced a novel X‑ray method for the nanotomography of bulk magnets, which they demonstrated in experiments at the Swiss Light Source SLS [2]. That advance opened up a unique window into the inner life of magnets, providing a tool for determining three-dimensional magnetic configurations at the nanoscale within micrometre-sized samples.

Utilizing these capabilities, members of the original team, together with international collaborators, now ventured into new territory. The stunning loop shapes they observed appear in the same GdCo2 micropillar samples in which they had before detected complex magnetic configurations consisting of vortices — the sort of structures seen when water spirals down from a sink — and their topological counterparts, antivortices. That was a first, but the presence of these textures has not been surprising in itself. Unexpectedly, however, the scientists also found loops that consist of pairs of vortices and antivortices. That observation proved to be puzzling initially. With the implementation of novel sophisticated data-analysis techniques they eventually established that these structures are so-called vortex rings — in essence, doughnut-shaped vortices.

Read more on the PSI website

Image: Magnetic beauty within. Reconstructed vortex rings inside a magnetic micropillar.

Credit: Claire Donnelly

Bone breakages and hip fracture risk is linked to nanoscale bone inflexibility

Bone breakages and hip fracture risk is linked to nanoscale bone inflexibility

Experiments carried out at Diamond using high energy intense beams of X-rays examined bone flexibility at the nanoscale. This allowed scientists to assess how collagen and minerals within bone flex and then break apart under load – in the nanostructure of hip bone samples.  

The report’s findings suggest that doctors should look not only at bone density, but also bone flexibility, when deciding how to prevent bone breakages. 

New research undertaken at Diamond’s Small Angle X-ray Scattering beamline (I22) has highlighted a gap in preventative treatment in patients prone to bone fractures.  The study, published in Scientific Reports and led by Imperial College London, found that flexibility as well as density in the bone nanostructure is an important factor in assessing how likely someone is to suffer fractures. 

Read more on the Diamond website

Image: Nanostructure: Collagen and mineral strain under load. Image: Shaocheng Ma, Imperial College London.