Boron atoms stretch out, gain new powers

Rice simulations demonstrate 1-D material’s stiffness, electrical versatility

Hold on, there, graphene. You might think you’re the most interesting new nanomaterial of the century, but boron might already have you beat, according to scientists at Rice University.

A Rice team that simulated one-dimensional forms of boron — both two-atom-wide ribbons and single-atom chains — found they possess unique properties. The new findings appear this week in the Journal of the American Chemical Society.

For example, if metallic ribbons of boron are stretched, they morph into antiferromagnetic semiconducting chains, and when released they fold back into ribbons.

In The News

Ultra-flat circuits will have unique properties

Rice University lab studies 2-D hybrids to see how they differ from common electronics

The old rules don’t necessarily apply when building electronic components out of two-dimensional materials, according to scientists at Rice University.2d-junct

The Rice lab of theoretical physicist Boris Yakobson analyzed hybrids that put 2-D materials like graphene and boron nitride side by side to see what happens at the border. They found that the electronic characteristics of such “co-planar” hybrids differ from bulkier components.

Their results appear this month in the American Chemical Society journal Nano Letters.

Shrinking electronics means shrinking their components. Academic labs and industries are studying how materials like graphene may enable the ultimate in thin devices by building all the necessary circuits into an atom-thick layer.

– See more at Rice News

Polyphony in B flat

At last, experiments offer two-dimensional boron… on a silver platterb_cards

In an extensive “News & Views” in Nature Chemistry, we provide a critical view of the latest breakthrough in materials flatland: the synthesis of two-dimensional boron. It also reflects on a decade-long effort in Yakobson’s group towards understanding and eventually predicting the structure of low-dimensional boron: from the B80 fullerene, to the polymorphism of 2D boron, to practical routes for its synthesis.

New Materials for Better Electronics

2016 CASC Brochure features work from the group

casc2016An image illustrating recent work from the group is featured in the 2016 Brochure
published by the Coalition for Academic Scientific Computation – an alliance of 85 of America’s most forward thinking research universities, national labs and computing centers, including Rice’s Ken Kennedy Institute for Information Technology.
On page 13, the highlight box “New Materials for Better Electronics” features our recent work on two-dimensional black phosphorus.

2D Boron among the Angew. Chem. covers

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Two-dimensional boron would take different forms, depending on the substrate used in chemical vapor deposition growth. Image by Zhuzha Zhang

Our most recent work on 2D boron will be featured on a cover of the upcoming issue of Angewandte Chemie International Edition. The study builds on two of our previous works on two-dimensional boron  and provides further clues as to how this elusive material can be synthesized and what the product may look like.

Calculation of the atom-by-atom energies involved in creating a sheet of boron revealed that the metal substrate – the surface upon which two-dimensional materials are grown in a chemical vapor deposition (CVD) furnace – would make all the difference.

The new calculations show it may be possible to guide the formation of 2D boron by tailoring boron-metal interactions.Theoretical physicist Boris Yakobson and his Rice colleagues discovered that copper, a common substrate in graphene growth, might be best to obtain flat boron, while other metals would guide the resulting material in their unique ways.

– See more at: Rice News

“Why nanotubes grow chiral” earns a spot in C&EN Nanotube hiStory

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JUNE 8, 2015 ISSUE, VOL. 93 | ISS. 23 Twists And Shouts: A Nanotube Story Nanotechnology’s chiral superstars were overshadowed by hype, but researchers believe they still have potential

The June 8 issue of the American Chemical Society‘s C&EN magazine quotes Boris Yakobson in its Cover Story “Twists And Shouts: A Nanotube Story“.

The timeline of major events in the history of carbon nanotubes features the Artyukhov–Penev–Yakobson (APY) theory of nanotube chirality in the most recent “Nanotubes Today” chapter. The APY theory combines the nanotube/catalyst interface thermodynamics with the kinetic growth theory to show that the unusual near-armchair peaks, repeatedly revealed in catalytic growth experiments over the last decade, emerge from the two antagonistic trends at the interface: energetic preference towards achiral versus the faster growth kinetics of chiral nanotubes. This narrow distribution is inherently related to the peaked behaviour of a simple function, xe−x.

The ultimate diamond slab…

among the most cited articles in Diamond and Related Materials published since 2010
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The ultimate diamond slab: GraphAne versus graphEne” is one of the early works from the group presenting a comprehensive characterization of three carbon nanomaterials of technological interest: graphEne, graphAne, and fluorinated graphene. By means of first principles and tight-binding calculations in combination with analytical methods, we carried out detailed comparative studies of their structural, mechanical, thermal, and electronic properties. The calculated elastic properties of these materials confirmed their high mechanical stability and stiffness, which in association with their low dimensionality, translates into a large ballistic thermal conductance. Furthermore, we showed that while graphene is a zero-gap semi-metal, graphane and fluorinated graphene are wide gap semiconductors. Here we also discussed designed interfaces between these systems, and showed that their physical properties have potential applications in nanoelectronic devices.

Editor’s Highlights for Carbon selects our work on fibers

A recent work from the group on atomistic modeling of carbon fibers appears in the quarterly Editor’s Highlights for Carbon. These articles are handpicked by the Editors for the reader community and are made freely available for a limited time.

Carbon fiber structure is excessively complex and modeling attempts necessarily rely on various approximations. We have designed structural faults with atomistic details, pertaining to polyacrylonitrile (PAN) derived fibers, and probed them using large-scale molecular dynamics simulations to uncover trends and gain insight into the effect of local structure on the strength of the basic structural units (BSUs) and the role of interfaces between regions with different degrees of graphitization. Besides capturing the expected strength degrading with increasing misalignment, the designed basic structural units reveal atomistic details of local structural failure upon tensile loading.

The image shows an atomistic representation of a BSU (~ 40,000 atoms); for clarity part of the geometry is not rendered. A misoriented block  is highlighted. Load is applied along the fiber axis, as indicated by the thick arrow, by displacing thin slabs (“handles”) at the top and bottom of the system, schematically represented as plates.

Sinuous grain boundaries in graphene demystified

The January 21 issue of Adv. Funct. Mater. features on its back cover work on graphene grain boundaries

The image shows a simulated grain boundary stitching two graphene domains tilted at a 28° angle exhibits a well-defined sinuous shape, which is revealed to be energetically preferred. Such sinuous grain boundary, appeared to be a curved river on land, are highlighted by B. I. Yakobson and co-workers on page 367 as a new channel to explore novel electronic behavior in graphene and to reach the as yet unexplored flatlands of two-dimensional materials.

Sparking Industrial Breakthroughs

2015 CASC Brochure features work from the group

Images illustrating two works from the group are featured in the 2015 Brochure published by the Coalition for Academic Scientific Computation – an alliance of 79 of America’s most forward thinking research universities, national labs and computing centers, including Rice’s Ken Kennedy Institute for Information Technology.  On page 2, the  highlight box “Something new under the sun” shows a collage based on a recent Nanoscale paper, and our extensive sampling of the CNT end-caps energy landscape, published in ACS Nano, is featured in the top box on page 3.