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Category: materials

Researchers at Lancaster University have developed a new material that can store energy for months, and potentially years, at a time. The material can be activated by light, and then release the pent-up energy on demand in the form of heat.

The team started with a metal-organic framework (MOF), materials that are famous for being very porous and as such, having an extremely high surface area. That in turn allows them to hold onto large amounts of molecules, making them great for desalinating or filtering water, capturing carbon dioxide out of the air, or delivering drugs in the body.

For the new study, the Lancaster researchers tested out how well a MOF might be able to store energy. They started with a version of the material called a DMOF1, and loaded its pores with azobenzene molecules. This compound is excellent at absorbing light, which causes its molecules to physically change shape.

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Chemists at Martin Luther University Halle-Wittenberg (MLU) have developed a way to integrate liquids directly into materials during the 3D printing process. This allows, for example, active medical agents to be incorporated into pharmaceutical products or luminous liquids to be integrated into materials, which allow monitoring of damage. The study was published in Advanced Materials Technologies.

3D is now widely used for a range of applications. Generally, however, the method is limited to materials which are liquefied through heat and become solid after printing. If the finished product is to contain liquid components, these are usually added afterwards. This is time-consuming and costly. “The future lies in more complex methods that combine several production steps,” says Professor Wolfgang Binder from the Institute of Chemistry at MLU. “That is why we were looking for a way to integrate liquids directly into the material during the .”

To this endeavor, Binder and his colleague Harald Rupp combined common 3D printing processes with traditional printing methods such as those used in inkjet or laser printers. Liquids are added drop by drop at the desired location during the extrusion of the basic material. This allows them to be integrated directly and into the material in a targeted manner.

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Controlling magnetism, essential for a wide range of technologies, is impaired by the impossibility of generating a maximum of magnetic field in free space. Here, we propose a strategy based on negative permeability to overcome this stringent limitation. We experimentally demonstrate that an active magnetic metamaterial can emulate the field of a straight current wire at a distance. Our strategy leads to an unprecedented focusing of magnetic fields in empty space and enables the remote cancellation of magnetic sources, opening an avenue for manipulating magnetic fields in inaccessible regions.

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In a new study an international research team led by the University of Vienna has shown that structures built around a single layer of graphene allow for strong optical nonlinearities that can convert light. The team achieved this by using nanometer-sized gold ribbons to squeeze light, in the form of plasmons, into atomically-thin graphene. The results, which are published in Nature Nanotechnology are promising for a new family of ultra-small tunable nonlinear devices.

In the last years, a concerted effort has been made to develop plasmonic devices to manipulate and transmit through nanometer-sized devices. At the same time, it has been shown that nonlinear interactions can be greatly enhanced by using plasmons, which can arise when light interacts with electrons in a material. In a plasmon, light is bound to electrons on the surface of a conducting material, allowing plasmons to be much smaller than the light that originally created them. This can lead to extremely strong nonlinear interactions. However, plasmons are typically created on the surface of metals, which causes them to decay very quickly, limiting both the propagation length and nonlinear interactions. In this new work, the researchers show that the long lifetime of plasmons in and the strong nonlinearity of this material can overcome these challenges.

In their experiment, the research team led by Philip Walther at the University of Vienna (Austria), in collaboration with researchers from the Barcelona Institute of Photonic Sciences (Spain), the University of Southern Denmark, the University of Montpellier, and the Massachusetts Institute of Technology (USA) used stacks of two-dimensional materials, called heterostructures, to build up a nonlinear plasmonic device. They took a single atomic layer of graphene and deposited an array of metallic nanoribbons onto it. The metal ribbons magnified the incoming light in the graphene layer, converting it into graphene plasmons. These plasmons were then trapped under the gold nanoribbons, and produced light of different colors through a process known as harmonic generation. The scientists studied the generated light, and showed that, the nonlinear interaction between the graphene plasmons was crucial to describe the harmonic generation.

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Researchers have observed three-dimensional magnetic vortex rings in a real-world magnetic material for the first time. Contrary to theoretical predictions, these rings – which are spin configurations within the material’s bulk – are remarkably stable and could move through the material like smoke rings move through air. If such movement can be controlled, they might have applications in energy-efficient 3D data storage and processing.

In a ferromagnetic material, the spatial distribution of the local magnetization is responsible for the material’s magnetic properties. These spatial distributions can be very complex, and intricate magnetic “textures” are behind many modern technologies, including hard disk drives. A vortex is one such distribution, and it forms when the material’s magnetization circulates around a central core.

Vortex rings are more sophisticated still, and occur naturally in physical systems such as fluids, plasmas and turbulent gases in the Earth’s atmosphere. However, while they have long been predicted to exist in ferromagnets, they have never been observed there until now.

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Potholes may soon reach the end of the road, as an Oxfordshire village hosts the first UK trial of a graphene-based wonder material designed to prevent cracks forming.

Graphene is a super-strong material made of specially-structured carbon.

Work will begin today on laying a 820 yard (750 metre) –long stretch of the wonder material on the main road through Curbridge, west of Oxford.

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