Category Archives: nanotubes

Growing pure nanotubes is a stretch, but possible

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Rice theorists show how tight “diet” could produce single-chirality carbon nanotubes

Like a giraffe stretching for leaves on a tall tree, making carbon nanotubes reach for food as they grow may lead to a long-sought breakthrough.

Materials theorists Boris Yakobson and Ksenia Bets at Rice University’s George R. Brown School of Engineering show how putting constraints on growing nanotubes could facilitate a “holy grail” of growing batches with a single desired chirality.

Their paper in Science Advances describes a strategy by which constraining the carbon feedstock in a furnace would help control the “kite” growth of nanotubes. In this method, the nanotube begins to form at the metal catalyst on a substrate, but lifts the catalyst as it grows, resembling a kite on a string.

Carbon nanotube walls are basically graphene, its hexagonal lattice of atoms rolled into a tube. Chirality refers to how the hexagons are angled within the lattice, between 0 and 30 degrees. That determines whether the nanotubes are metallic or semiconductors. The ability to grow long nanotubes in a single chirality could, for instance, enable the manufacture of highly conductive nanotube fibers or semiconductor channels of transistors.

– See more at Rice News

Nanotube fibers stand strong – but for how long?

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Rice scientists calculate how carbon nanotubes and their fibers experience fatigue

Up here in the macro world, we all feel fatigue now and then. It’s the same for bundles of carbon nanotubes, no matter how perfect their individual components are.

A Rice University study calculates how strains and stresses affect both “perfect” nanotubes and those assembled into fibers and found that while fibers under cyclic loads can fail over time, the tubes themselves may remain perfect. How long the tubes or their fibers sustain their mechanical environment can determine their practicality for applications.

That made the study, which appears in Science Advances, important to Rice materials theorist Boris Yakobson,graduate student Nitant Gupta and assistant research professor Evgeni Penev of Rice’s George R. Brown School of Engineering. They quantified the effects of cyclic stress on nanotubes using state-of-the-art simulation techniques like a kinetic Monte Carlo method. They hope to give researchers and industry a way to predict how long nanotube fibers or other assemblies can be expected to last under given conditions.

– See more at Rice News

A little friction goes a long way toward stronger nanotube fibers

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Rice model may lead to better materials for aerospace, automotive, medical applications

Carbon nanotube fibers are not nearly as strong as the nanotubes they contain, but Rice University researchers are working to close the gap.

A computational model by materials theorist Boris Yakobson and his team at Rice’s Brown School of Engineering establishes a universal scaling relationship between nanotube length and friction between them in a bundle, parameters that can be used to fine-tune fiber properties for strength.

The model is a tool for scientists and engineers who develop conductive fibers for aerospace, automotive, medical and textile applications like smart clothing. Carbon nanotube fibers have been considered as a possible basis for a space elevator, a project Yakobson has studied.

The research is detailed in the American Chemical Society journal ACS Nano.

– See more at Rice News

CNT-graphene-borophene specialty cake

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A sweet way to say “Happy Holidays”

Not everyone can make cakes, but a great cake can come from anyone… or so it seems. Combining many years of experience in modeling the synthesis of carbon nanotubes (CNTs) and 2D materials, and obviously some serious culinary skills Ksenia Bets has scaled-up their production to say “Happy Holidays” on behalf of Yakobson’s group and the MSNE department.

The cake blends a candy nanotube (CNT), graphene and borophene from sugar (or possibly other solid sources) on a stepped glazed surface. The MSNE logo can also be seen on the top terrace.

For recipes visit this page.

Double-walled nanotubes have electro-optical advantages

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Rice University calculations show they could be highly useful for solar panels

One nanotube could be great for electronics applications, but there’s new evidence that two could be tops.

Rice University engineers already knew that size matters when using single-walled carbon nanotubes for their electrical properties. But until now, nobody had studied how electrons act when confronted with the Russian doll-like structure of multiwalled tubes.

The Rice lab of materials theorist Boris Yakobson has now calculated the impact of curvature of semiconducting double-wall carbon nanotubes on their flexoelectric voltage, a measure of electrical imbalance between the nanotube’s inner and outer walls.

This affects how suitable nested nanotube pairs may be for nanoelectronics applications, especially photovoltaics.

The theoretical research by Yakobson’s Brown School of Engineering group appears in the American Chemical Society journal Nano Letters.

– See more at Rice News