Putting the Power in Power-Dressing

Scientists in the UK developing wearable electronics have knitted a flexible fabric that delivers twice the power output of current energy harvesting textiles.

There is considerable interest and research into wearable piezoelectric energy harvesters that use waste energy from human movement or the ambient environment to power low-energy consuming wearable devices, such as wireless sensors and consumer electronics.

 

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The fabric is composed of two separate conducting, silver-coated polyamide textile faces joined together by a PVDF spacer yarn. Credit: Navneet Soin et al.

Graphene’s Love Affair with Water

Graphene has proven itself as a wonder material with a vast range of unique properties. Among the least-known marvels of graphene is its strange love affair with water.

Graphene is hydrophobic – it repels water – but narrow capillaries made from graphene vigorously suck in water allowing its rapid permeation, if the water layer is only one atom thick – that is, as thin as graphene itself.

This bizarre property has attracted intense academic and industrial interest with intent to develop new water filtration and desalination technologies.

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Credit: Dr Rahul Nair and Prof Andre Geim, The University of Manchester

Diamond Film Possible Without the Pressure

Perfect sheets of diamond a few atoms thick appear to be possible even without the big squeeze that makes natural gems.

Scientists have speculated about it and a few labs have even seen signs of what they call diamane, an extremely thin film of diamond that has all of diamond’s superior semiconducting and thermal properties.

Now researchers at Rice University and in Russia have calculated a “phase diagram” for the creation of diamane. The diagram is a road map. It lays out the conditions – temperature, pressure and other factors – that would be necessary to turn stacked sheets of graphene into a flawless diamond lattice.

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The phase diagram developed by scientists at Rice University and in Moscow describes the conditions necessary for the chemical creation of thin films of diamond from stacks of single-atomic-layer graphene. (Credit: Pavel Sorokin/Technological Institute for Superhard and Novel Carbon Materials)

Rice’s Carbon Nanotube Fibers Outperform Copper

On a pound-per-pound basis, carbon nanotube-based fibers invented at Rice University have greater capacity to carry electrical current than copper cables of the same mass, according to new research.

While individual nanotubes are capable of transmitting nearly 1,000 times more current than copper, the same tubes coalesced into a fiber using other technologies fail long before reaching that capacity.

But a series of tests at Rice showed the wet-spun carbon nanotube fiber still handily beat copper, carrying up to four times as much current as a copper wire of the same mass.

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Scanning electron microscope images show typical carbon nanotube fibers created at Rice University and broken into two by high-current-induced Joule heating. Rice researchers broke the fibers in different conditions – air, argon, nitrogen and a vacuum – to see how well they handled high current. The fibers proved overall to be better at carrying electrical current than copper cables of the same mass. (Credit: Kono Lab/Rice University

Cementing Radioactive Waste

Cement would make a useful material for locking away radioactive waste except for the fact that conventional cement is susceptible to weathering. When water infiltrates its pores, it freezes and when it thaws, the resulting cracks can fracture the cement blocks. Moreover, adding foreign materials to the standard cement slows the hydration process required for the mix to harden leading to greater porosity and an increased risk of radioactive elements leaching out through long-term wear and tear.

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Credit: http://www.iucr.org

Researchers Build Nonflammable Lithium Ion Battery

In studying a material that prevents marine life from sticking to the bottom of ships, researchers led by chemist Joseph DeSimone at the University of North Carolina at Chapel Hill have identified a surprising replacement for the only inherently flammable component of today’s lithium-ion batteries: the electrolyte.

The work, published in the Feb. 10 issue of the Proceedings of the National Academy of Sciences, paves the way for developing a new generation lithium-ion battery that doesn’t spontaneously combust at high temperatures. 

The discovery also has the potential to renew consumer confidence in a technology that has attracted significant concern—namely, after recent lithium battery fires in Boeing 787 Dreamliners and Tesla Model S vehicles.

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Credit: http://www.unc.edu

Graphene-like material made of boron a possibility, experiments suggest

Graphene has been heralded as a wonder material. Made of a single layer of carbon atoms in a honeycomb arrangement, graphene is stronger pound-for-pound than steel and conducts electricity better than copper. 

Since the discovery of graphene, scientists have wondered if boron, carbon’s neighbor on the periodic table, could also be arranged in single-atom sheets. 

Theoretical work suggested it was possible, but the atoms would need to be in a very particular arrangement.

Boron has one fewer electron than carbon and as a result can’t form the honeycomb lattice that makes up graphene. 

For boron to form a single-atom layer, theorists suggested that the atoms must be arranged in a triangular lattice with hexagonal vacancies — holes — in the lattice.

 

Unlocking the secrets of the B₃₆ cluster A 36-atom cluster of boron, left, arranged as a flat disc with a hexagonal hole in the middle, fits the theoretical requirements for making a one-atom-thick boron sheet, right, a theoretical nanomaterial dubbed “borophene.” Credit: Wang lab/Brown University

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Phosphorene discovery positively impacts 2D electronics

US researchers have made phosphorus into an analogue of graphene, dubbed phosphorene, allowing practical electronic devices made from such two-dimensional materials. Peide Ye at Purdue University, US, and his co-workers show that phosphorene is the first native 2D electron-poor – or p-type – semiconductor. That’s important for making these flat materials into standard complementary metal-oxide semiconductor (CMOS) logic circuit elements, which Ye’s team has also achieved with phosphorene. ‘For device applications it’s fundamentally better than graphene,’ Ye says. Read more here...

The ridged structure of phosphorene explains the directional electrical performance dependence that Ye's team saw © Peide Ye

New Salt Compounds Challenge the Foundation of Chemistry

All good research breaks new ground, but rarely does the research unearth truths that challenge the foundation of a science. That’s what Artem R. Oganov has done, and the professor of theoretical crystallography in the Department of Geosciences will have his work published in the Dec. 20 issue of the journal Science.

The paper titled "Unexpected stable stoichiometries of sodium chlorides,” documents his predictions about, and experiments in, compressing sodium chloride—rock salt—to form new compounds. These compounds validate his methodology for predicting the properties of objects—a methodology now used worldwide for computational material discovery—and hold the promise of novel materials and applications. 

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Electron localization function in the cubic NaCl3 structure. (Credit: Artem R. Oganov)

Graphene-Based Field-Effect Transistor With Semiconducting Nature Opens Up Practical Use in Electronics

UNIST announced a method for the mass production of boron/nitrogen co-doped graphene nanoplatelets, which led to the fabrication of a graphene-based field-effect transistor (FET) with semiconducting nature. This opens up opportunities for practical use in electronic devices. 

The Ulsan National Institute of Science and Technology (UNIST) research team led by Prof. Jong-Beom Baek have discovered an efficient method for the mass production of boron/nitrogen co-doped graphene nanoplatelets (BCN-graphene) via a simple solvothermal reaction of BBr3/CCl4/N2 in the presence of potassium. This work was published in “Angewandte Chemie International Edition” as a VIP (“Very Important Paper”).

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A schematic representation for the formation of BCN-graphene via solvothermal reaction between carbon tetrachloride (CCl4) boron tribromide (BBr3) and nitrogen (N2) in the presence of potassium (K). Photograph is of the autoclave after the reaction, showing the formation of BCN-graphene (black) and potassium halide (KCl and KBr, white).

 

Researchers Grow Liquid Crystal 'Flowers' That Can Be Used as Lenses

A team of material scientists, chemical engineers and physicists from the University of Pennsylvania has made another advance in their effort to use liquid crystals as a medium for assembling structures. 

In their earlier studies, the team produced patterns of “defects,” useful disruptions in the repeating patterns found in liquid crystals, in nanoscale grids and rings. 

The new study adds a more complex pattern out of an even simpler template: a three-dimensional array in the shape of a flower. And because the petals of this “flower” are made of transparent liquid crystal and radiate out in a circle from a central point, the ensemble resembles a compound eye and can thus be used as a lens. 

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A liquid crystal "flower" under magnification. The black dot at center is the silica bead that generates the flower's pattern. (Credit: Image courtesy of University of Pennsylvania)

Metamaterials offer route to room-temperature superconductivity

Metamaterials offer route to room-temperature superconductivity

A new way of making high-temperature superconductors that is based on metamaterials has been proposed by physicists in the US. Their plan involves combining a low-temperature superconductor with a dielectric material to create a metamaterial that is a superconductor at much higher temperatures than its constituent materials. The team is now looking at testing its proposal in the lab and is hopeful that its work could offer a route to creating a superconductor that operates at room temperature.

Metamaterial superconductors at liquid nitrogen temperatures?

Making a Gem of a Tiny Crystal: Slowly Cooled DNA Transforms Disordered Nanoparticles Into Orderly Crystal

Nature builds flawless diamonds, sapphires and other gems. Now a Northwestern University research team is the first to build near-perfect single crystals out of nanoparticles and DNA, using the same structure favored by nature.

"Single crystals are the backbone of many things we rely on -- diamonds for beauty as well as industrial applications, sapphires for lasers and silicon for electronics," said nanoscientist Chad A. Mirkin. "The precise placement of atoms within a well-defined lattice defines these high-quality crystals. 

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Cut diamond. Nature builds flawless diamonds, sapphires and other gems. Now a Northwestern University research team is the first to build near-perfect single crystals out of nanoparticles and DNA, using the same structure favored by nature. (Credit: © tiero / Fotolia)

Credit: Northwestern University research team

Steering Electrons Along Chemical Bonds

Electron motions induced by a strong electric field are mapped in space and time with the help of femtosecond x-ray pulses. An x-ray movie of the crystal lithium hydride shows that the electric interaction between electrons has a decisive influence on the direction in which they move. An ionic crystal is a regular arrangement of positively and negatively charged ions in space. 

Crystals with rock salt structure. Upper crystal: sodium chloride (NaCl) with blue balls for Na+ ions and green balls for Cl- ions. Lower crystal: lithium hydride (LiH) with small blue balls for Li0.5+ ions and white balls for H0.5- ions. The grey-shaded plane indicates the sectional views. (Credit: MBI)

Credit: http://www.fv-berlin.de

Device Captures Signatures and Fingerprints With Tiny LEDs

Researchers at the Georgia Institute of Technology want to put your signature up in lights -- tiny lights, that is. Using thousands of nanometer-scale wires, the researchers have developed a sensor device that converts mechanical pressure -- from a signature or a fingerprint -- directly into light signals that can be captured and processed optically.

The sensor device could provide an artificial sense of touch, offering sensitivity comparable to that of the human skin. Beyond collecting signatures and fingerprints, the technique could also be used in biological imaging and micro-electromechanical (MEMS) systems. Ultimately, it could provide a new approach for human-machine interfaces.

This schematic shows a device for imaging pressure distribution by the piezo-phototronic effect. The illustration shows a nanowire-LED based pressure sensor array before (a) and after (b) applying a compressive strain. A convex character pattern, such as "ABC," molded on a sapphire substrate, is used to apply the pressure pattern on the top of the indium-tin oxide (ITO) electrode. (Credit: Courtesy of Zhong Lin Wang)

 Credit: Georgia Institute of Technology

Q-Glasses Could Be a New Class of Solids

There may be more kinds of stuff than we thought. A team of researchers has reported possible evidence for a new category of solids, things that are neither pure glasses, crystals, nor even exotic quasicrystals. Something else.

"Very weird. Strangest material I ever saw," says materials physicist Lyle Levine of the National Institute of Standards and Technology (NIST).

The research team from NIST and Argonne National Laboratory has analyzed a solid alloy that they discovered in small discrete patches of a rapidly cooled mixture of aluminum, iron and silicon. 

The material appears to have none of the extended ordering of atoms found in crystals, which would make it a glass, except that it has a very defined composition and grows outward from "seeds"—things that glasses most assuredly do not do.

 

The odd microstructure of this aluminum-iron-silicon mixture is seen in this image. The round nodules are the q-glass, not crystalline but with a well-defined chemical composition. The spherical shape indicates that they grow from an initial seed. The nodules use up iron and silicon in the mixture until the surrounding concentration of aluminum gets high enough to start forming aluminum crystals, seen as long bright lines radiating from the nodules. (Color added for clarity.) (Credit: Bendersky/NIST)

Credit: http://www.nist.gov

Fullerenes

The 1996 Nobel Prize for Chemistry has been won by Harold W. Kroto, Robert F. Curl and Richard E. Smalley for their discovery in 1985 of a new allotrope of carbon, in which the atoms are arranged in closed shells. The new form was found to have the structure of a truncated icosahedron, and was named Buckminsterfullerene, after the architect Buckminster Fuller who designed geodesic domes in the 1960's. For more click here.

 

 
Courtesy: Dr. Peter Unwin

Bragg's Law and Diffraction:

Bragg's Law refers to the simple equation:

n = 2d sin 

derived by the English physicists Sir W.H. Bragg and his son Sir W.L. Bragg in 1913 to explain why the cleavage faces of crystals appear to reflect X-ray beams at certain angles of incidence (theta, ). The variable d is the distance between atomic layers in a crystal, and the variable lambda is the wavelength of the incident X-ray beam (see applet); n is an integer. For more click here.

Courtesy: http://skuld.bmsc.washington.edu 

Solid State Structure

Atoms can be gathered together as an aggregate through a number of different processes, including condensation, pressurization, chemical reaction, electrodeposition, and melting. The process usually determines, at least initially, whether the collection of atoms will take to form of a gas, liquid or solid. For more click here.

Courtesy: http://www.ndt-ed.org/EducationResources