Raphael Thys
Representative image of a metallic wire. iStock
The thinnest metallic wire may have just been discovered.
A group of researchers from Switzerland’s École Polytechnique Fédérale de Lausanne (EPFL) believe this newly designed wire might be the thinnest metallic nanowire ever created; so much so that it can also remain stable at 0 degrees Kelvin.
Chiara Cignarella was the lead author of the project. The team also consisted of Davide Campi and Nicola Marzari.
Team develops an algorithm to identify and exfoliate stable 1D metallic nanowires
The team wondered if they could somehow leverage crystalline structures to identify a perfect candidate, sans building thousands of them in a lab.
The researchers were mostly on the lookout for 3D crystals with the right structural and electronic properties, so they could be “exfoliated.” 2D materials like graphene were extracted using this process from 3D.
However, this would be the first time researchers exfoliated one-dimensional materials like carbon nanotubes. This approach created a database of around 78,000 known 3D crystalline structures.
These were cobbled together from a set of different scientific databases across the globe. The researchers concentrated on crystals held together by Van Der Waals forces, according to the press release.
After this, they created a special algorithm to sort out the data collected from the database. “We were looking specifically for metallic wires, which are supposed to be difficult to find because 1-D metals, in principle, should not the sufficiently stable to allow for exfoliation”, says Cignarella, who is the first author of the paper.
If the algorithm is correct it could help in identifying crystals “whose spatial organization of atoms contained natural wire-like threads. It would also calculate precisely how much energy would be required to separate these one-dimensional nanowires from the rest of the baseline crystal, which is critical in determining how viable they would be to actually fabricate,” according to an article in DeBrief.
The selection process identified top candidates for stable metallic nanowires
The team was able to finally bring down the list to 800 visible candidates.
They further shortlisted 14 candidates and selected four of them.
Two among them were metals and the other two were semimetals. Notable among the lot was a straight-line chain consisting of two carbon atoms and a copper atom.
It revealed the conducive properties of the wire while remaining at a normal temperature. This happened because the chain was resistant to distortion from Peierl distortions, or breaks in the 1D strings.
“It’s really interesting because you would not expect an actual wire of atoms along a single line to be stable in the metallic phase,” Cignarella opined.
Discovery of 1D metallic nanowires and Sb2Te2 semi-metal for quantum applications
The researchers mentioned their 1D wire could be exfoliated from three distinct crystal sources — NaCuC2, KCuC2 and RbCuC2. “It requires little energy to be extracted from them,” the release explains, “and its chain can be [bent] while preserving its metallic properties, which would make it interesting for flexible electronics.”
A one-dimensional metallic wire CuC2, it’s a single chain of two carbon atoms and one copper atom. Credit: Chiara Cignarella, Davide Campi, and Nicola Marzari.
The team also made some other discoveries. They caught hold of one semi-metal, Sb2Te2. It could help physicists study excitonic insulators. If things work according to plan, Sb2Te2 might even allow quantum phenomena to become visible at macroscopic scales.
According to the study authors, “both things will be fundamental to understanding how they would perform in real-world applications.”
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The original study was published in Marvel.
Abstract
Researchers at EPFL have employed computational tools to look for new 1-D materials that could be exfoliated from known three-dimensional crystals. Out of an initial list of over 780,000 crystals, they came up with a list of 800 1-D materials, out of which they selected the 14 best candidates – compounds that have not been synthesized as actual wires yet, but that simulations suggest as feasible. Among them is the metallic wire CuC2, a straight-line chain composed by two carbon atoms and one copper atom, the thinnest metallic nanowire stable at 0 K found so far. The article is published in ACS Nano.
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Gairika Mitra Gairika is a technology nerd, an introvert, and an avid reader. Lock her up in a room full of books, and you'll never hear her complain.