nanowires – Lightsources.org

Smart glass and music from SLS

2023/11/212023/12/20

Every year the PSI Founder Fellowship Programme supports new ideas for innovative applications with up to 150,000 Swiss francs. Whether smart glass or music restoration at the synchrotron – the resulting spin-offs are as diverse as the research at PSI.

Glass is no modern invention – in fact, archaeological finds show that this material has been manufactured and used by humans for more than 5,000 years. Glass is not only used as a vessel for fine wines – optical lenses are also ground from glass to make the smallest or most distant objects visible. Our communications flow through glass fibres in optical cables. Windows keep out the wind and rain while letting light pass through. The translucent material finds application in numerous areas of our civilisation. Yet glass is not just glass – we adapt it to our needs and reinvent it more or less constantly.

Barbara Horvath works with glass. The materials scientist, a candidate for the PSI Founder Fellowship, has been working to establish her spin-off Inveel since August of this year. Using tiny nanowires, the young entrepreneur wants to print electrodes on glass, for example to change its optical and electrical properties.

Smart glass

“One possible application for our technology is socalled switchable glass – also called smart glass,” Horvath explains. “That is a special material that can turn opaque, transparent dark or coloured, automatically or at the touch of a button.” This capability is enabled by a thin nanostructured coating sandwiched between two panes of glass. When electrical charges are applied to this layer, it becomes optically active and can change its colour as a result. This not only puts privacy at your fingertips, but can also be used to regulate the temperature in buildings.

The invention itself is not new. Such glass is already in use for windows in modern office buildings and aircraft, for example. However, producing them is very complex and thus costly. “To be able to apply the weak electrical charges to the switchable glass, thin wires must be accommodated – so thin that they will not impair visibility,” Horvath explains.

During her work at PSI, Horvath and her group leader Helmut Schift developed a method for the production of such fine conductor tracks. “Our method makes it possible to produce wires with a diameter of around one hundred nanometres,” the scientist explains. It functions much like a printer: nanoparticles are applied as liquid droplets and fuse together to form linear structures. This allows large areas to be printed with extremely fine, parallel conductors. Using conductive materials such as silver and gold, a wide variety of surfaces can be furnished with invisible electronics quickly and inexpensively.

Switchable glass is just one possible application. The nanowires could also be used to change the direction of polarisation of incident light in the glass so that only certain wavelengths penetrate. This could be used, for example, for temperature control in greenhouses or for laser protection in eyeglasses. “In the laboratory, we have shown that the technology works in principle,” Horvath adds. “The Founder Fellowship has now made it possible for us to take the next step towards practical applications.”

Read more on PSI website

Image: Barbara Horvath wants to use thin nanowires to alter the optical and electrical properties of glass.

Credit: Paul Scherrer Institute/Markus Fischer

Novel protocol for mass production of nanowires

2021/12/022021/12/02

Nanotechnology is one of the major driving forces behind the technological revolution of this century and nanomaterials play a key role in this revolution. While the use of nanoparticles is widespread in industrial applications, the use of nanowires -wires with a diameter of only a few nanometres- is mostly reduced to scientific areas. The fields of biomedicine and permanent magnets would benefit from the cost-effective mass production of nanowires.

In a recent publication, researchers from the Universidad Complutense de Madrid (UCM) and various centres from the Consejo Superior de Investigaciones Científicas (CSIC), in collaboration with ALBA, have established a novel and sustainable synthesis protocol that allows obtaining a greater number of nanowires than conventional laboratory fabrication processes with considerably reduced production time and cost.

The goal of this project was to increase the production of metallic nanowires, reducing costs and timings to expand their applicability to industry. Due to the high costs associated with the high-purity aluminium normally used as the starting material, as well as with the low temperature and large anodization time, the commercial application of nanowires using anodized aluminium oxide is still limited by their fabrication process.

“Nano-Barber poles”: Helical surface magnetization in nanowires

2020/11/052020/11/12

Nanomagnetism is nowadays expanding into three dimensions, triggered by the discovery of new magnetic phenomena and their potential use in applications. This shift towards 3D structures should be accompanied by strategies and methodologies to map the tridimensional spin textures associated.

A new study fruit of a collaboration of researchers from two beamlines at ALBA Synchrotron (CIRCE and MISTRAL), with the participation of the Universidad Complutense de Madrid, IMDEA Nanociencia and the Universidad de Salamanca shows that cylindrical nanowires have at the center a magnetization aligned with the axis of the wire and at the surface a magnetization that describes helical lines as the barber poles. The helicity provides chirality to the magnetic configuration since it can be right or left-handed. Researchers found out that two adjacent magnetic domains having opposite chirality are more difficult to move than two adjacent domains with the same chirality. This result evidences the role of the chirality on the dynamics of the domain walls that might be used as a practical variable for magnetic data storage.

Read more on the ALBA website

Image: Figure. (Left) Barber pole illustrating the helical lines that the magnetization describes at the surface of the wires. (Right) Schematics of the configuration of the magnetization of the initial state of the nanowire together with the magnetic images before and after the application of magnetic field pulses. In the initial state, the two domain walls signaled with orange arrows separate domains with the same chirality. Note that the head-to-head or tail-to-tail domains have the same chirality in spite of having opposite signs of surface magnetization. The green arrow separates two domains of different chirality since while having the same axial orientation, the surface helicity is opposite. Magnetic field pulses of 120 mT move the walls separating domains with the same chirality but not the green wall separating opposite chirality.