Synthesizing nanodiamond-like carbon chains inside nanotubes

The inner space of carbon nanotubes can act as a template for the synthesis of nanodiamond-like carbon chains. As a team of scientists from Japan, Germany, and the United States report in the journal ("Template Synthesis of Linear-Chain Nanodiamonds Inside Carbon Nanotubes from Bridgehead-Halogenated Diamantane Precursors"), this templated polymerization approach paves the way for the design of novel one-dimensional nanomaterials. Diamond-like Chains Inside Carbon Nanotubes Diamond-like Chains Inside Carbon Nanotubes Nanosized materials such as nanowires offer unique properties that are completely distinct from those of the bulk materials. However, one-dimensional nanostructures are difficult to synthesize. In an international cooperation, Hisanori Shinohara from Nagoya University in Japan and his colleagues have developed a method that uses carbon nanotubes as a reaction vessel for the templated polymerization of linear-chain nanomaterials. Template-Based Approach for 1D Structures The idea was that during polymerization, the small precursor molecules would naturally adopt the one-dimensional structure of the tubes only if their inner diameter is small enough. Larger diameters would offer too much space so that the polymerization could terminate or become uncontrolled. By using this method, Shinohara and his colleagues were able to synthesize a one-dimensional nanodiamond polymeric structure by a relatively simple annealing technique. They describe their approach: "The present template-based approach for the synthesis of linear-chain diamondoid polymers is entirely different from conventional chemical approaches." Polymerization of Diamantane The scientists used diamantane, a 10-carbon cage structure, as a precursor molecule and building block for polymerization. This molecule was brominated at either side so that, upon addition of iron nanoparticles, the bromine would be abstracted and a diradical formed. In a normal chemical polymerization reaction, the formed radicals would abstract hydrogen for termination reactions, but: "To our great surprise, the radicals are persistent and recombined with each other inside the carbon nanotubes," the authors write. And: "Depending on the inner diameter of the carbon nanotubes, the inserted species can either be transformed into the linear-chain polymers or into amorphous carbon." As a result, the structures formed in the 1 nm-sized tubes were a polymeric chain of nanodiamondoids, which could be visualized impressively by electron microscopy. To put it more colloquially, the formed carbon nanotubes filled with the nanodiamondoid polymer look like macaroni filled with spaghetti. In order to extract the inner polymer, a solution-phase sonication/extraction can be applied, the group reports. The big advantage of the new method is the simplicity and specificity of the formation of the one-dimensional nanostructured polymer chain. This technique will certainly attract the attention of materials scientists.
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Turning clothing into information displays

Researchers from Holst Centre (set up by TNO and imec), imec and CMST, imec’s associated lab at Ghent University, have demonstrated the world’s first stretchable and conformable thin-film transistor (TFT) driven LED display laminated into textiles. This paves the way to wearable displays in clothing providing users with feedback. stretchable and conformable thin-film transistor (TFT) driven LED display The world’s first stretchable and conformable thin-film transistor (TFT) driven LED display laminated into textiles developed by Holst Centre, imec and CSMT. (click on image to enlarge) Wearable devices such as healthcare monitors and activity trackers are now a part of everyday life for many people. Today’s wearables are separate devices that users must remember to wear. The next step forward will be to integrate these devices into our clothing. Doing so will make wearable devices less obtrusive and more comfortable, encouraging people to use them more regularly and, hence, increasing the quality of data collected. A key step towards realizing wearable devices in clothing is creating displays that can be integrated into textiles to allow interaction with the wearer. “Wearable devices allow people to monitor their fitness and health so they can live full and active lives for longer. But to maximize the benefits wearables can offer, they need to be able to provide feedback on what users are doing as well as measuring it. By combining imec’s patented stretch technology with our expertise in active-matrix backplanes and integrating electronics into fabrics, we’ve taken a giant step towards that possibility,” says Edsger Smits, Senior research scientist at Holst Centre. The conformable display is very thin and mechanically stretchable. A fine-grain version of the proven meander interconnect technology was developed by the CMST lab at Ghent University and Holst Centre to link standard (rigid) LEDs into a flexible and stretchable display. The LED displays are fabricated on a polyimide substrate and encapsulated in rubber, allowing the displays to be laminated in to textiles that can be washed. Importantly, the technology uses fabrication steps that are known to the manufacturing industry, enabling rapid industrialization. Following an initial demonstration at the Society for Information Display’s Display Week in San Jose, USA earlier this year, Holst Centre has presented the next generation of the display at the International Meeting on Information Display (IMID) in Daegu, Korea, 18-21 August 2015. Smaller LEDs are now mounted on an amorphous indium-gallium-zinc oxide (a-IGZO) TFT backplane that employs a two-transistor and one capacitor (2T-1C) pixel engine to drive the LEDs. These second-generation displays offer higher pitch and increased, average brightness. The presentation will feature a 32x32 pixel demonstrator with a resolution of 13 pixels per inch (ppi) and average brightness above 200 candelas per square meter (cd/m2). Work is ongoing to further industrialize this technology.
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Shift from electronics to spintronics opens up possibilities of faster data

Electronics is based on measuring the tiny electrical charge of electrons passing through electronic circuits. An alternative approach under development is spintronics, which instead relies not on electrons’ charge, but on another of their fundamental quantum-mechanical properties: spin. Spin can be visualised as the Earth turning on its own axis while rotating around the sun. In the same way, an electron spins on its own axis while rotating around an atom’s nucleus. Spin is either “up” or “down”. In the same way traditional electronics uses charge to represent information as zeros and ones, the two spin states can be used to represent the same binary data in spintronics. Spin can be measured because it generates tiny magnetic fields. Ferrous metals such as iron become magnetic, for example, when enough particles have their spin set in the same direction, generating a magnetic field of the same polarity as the spin. Spintronics has several advantages over conventional electronics (pdf). Electronics require specialised semiconductor materials in order to control the flow of charge through the transistors. But spin can be measured very simply in common metals such as copper or aluminium. Less energy is needed to change spin than to generate a current to maintain electron charges in a device, so spintronics devices use less power. Spin states can be set quickly, which makes transferring data quicker. And because electron spin is not energy-dependent, spin is non-volatile – information sent using spin remains fixed even after loss of power. Upgrading hard disks using spin The first application of spintronics to computers saw Professors Albert Fert and Peter Grünberg awarded the 2007 Nobel Prize in Physics for their discovery of giant magnetoresistance (GMR). They realised it was possible to use electron spin to increase the rate at which information could be read from a hard disk drive and developed ground-breaking technology to harness this feature. hard drive A hard drive, showing circular platters and read/write head mounted at the tip of the arm. A hard disk drive stores data as ones and zeros encoded magnetically on rotating disk platters within the drive. The magnetic field is generated when electrons flow through wire coils mounted in the drive write heads which move across the face of the platters, changing the alignment of the magneto-sensitive particles on the platter surface. Reversing the electron flow reverses the field; the two directions represent one and zero. To read from the disk the process works in reverse. A GMR drive head consists of two ferromagnetic layers, one with a fixed magnetic field direction and the other free to align with the magnetic field encoded on the disk, with a non-magnetic layer sandwiched in between. When an electron passes through a magnetic field its spin state may change, known as scattering. Where electrons have random, scattered spin states this creates greater resistance to electric current. By aligning electrons’ spin state to that of the magnetic field in the layers of the drive head, GMR technology dramatically reduces resistance, speeding up data transfer. First introduced by IBM in 1997, GMR technology has led to faster and higher-density drives than was previously possible. A hard drive read/write head A hard drive read/write head. Putting a fresh spin on memory Spintronics researchers have since been working on introducing the same technology to computer memory, aiming to replace electric current-based dynamic random access memory (DRAM) with magnetic RAM (MRAM). The first commercial product by Everspin has been used in Airbus aircraft and BMW motorbikes due to its reliability under heat stress or cosmic-ray exposure – something that affects aircraft cruising at high altitudes. MRAM exploits the same spin-based magnetic field approach, but uses a magnetoresistance cell to store data rather than a spinning disk platter as in a hard drive. While it is not as fast as DRAM, magnetic cells are able to maintain their stored spin orientations, and so the data they represent, without power. MRAM is likely to replace commonly used flash memory such as SD cards and compact flash first, as it is faster and doesn’t suffer from flash memory’s limited lifespan. Other manufacturers such as Intel, Qualcomm, Toshiba and Samsung are developing MRAM to use as processor cache memory, where by virtue of their smaller size MRAM chips of greater capacity can be incorporated into smaller packages that will be faster, and use up to 80% less power than current cache memory. As electronics approaches the limits of silicon, spintronic components will play an important role in ensuring we enjoy steady performance gains, and faster, higher-capacity storage at lower power and cost.
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