Home Uncategorized Scientists discovered new structural variant of carbon: Penta-graphene

Scientists discovered new structural variant of carbon: Penta-graphene

This newly discovered structural variant of carbon named as Penta-graphene is a super-thin sheet of pure carbon made up of perfect little pentagons. It is semiconducting, strong and capable of withstanding temperatures
of up to 1,000 degrees Kelvin, and scientists predict it could
outperform ‘wonder material’ graphene in certain applications.

Research on this material has proved that it’s mechanically stable, so it
has a good stiffness; it’s thermally stable, which means it has a good
amount of resistance to decomposition at high temperatures; and
dynamically stable, so its structure won’t undergo any changes without
the influence of some kind of external force. And it has weird and wonderful properties that the team says makes it a great
candidate for applications in electronics, biomedicine, and
“The three last important forms of carbon that have been discovered were
fullerene, the nanotube, and graphene. Each one of them has unique
structure,” said lead researcher and US-based physicist Puru Jena, from the Virginia Commonwealth University (VCU). “Penta-graphene will belong in that category.”
Unlike most forms of carbon, which are made of hexagonal building blocks
and the occasional pentagon, penta-graphene is made exclusively of
pentagons. And the story behind how the researchers came to test out
this new carbon structure is actually really sweet. 
One of the team, Qian Wang, a professor at Peking University in China
and an adjunct professor at VCU, was having dinner with her husband at a
restaurant in Beijing, when she looked up at the walls and saw dozens
of pentagon-shaped tiles, reminiscent of the ones that line the streets
of Cairo in Egypt. “I told my husband, ‘Come, see! This is a pattern
composed only of pentagons,'” she said.
“I took a picture and sent it to one of my students, and said, ‘I think
we can make this. It might be stable. But you must check it carefully.’
He did, and it turned out that this structure is so beautiful, yet also
very simple.”

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So they modelled the structure on a computer program and created a
unique two-dimensional carbon allotrope made of pentagons. Simulations
suggest that it’s super-strong, and will not degrade at high
temperatures – even up to 1,000 degrees Kelvin. “You know the saying,
diamonds are forever? That’s because it takes a lot of energy to convert
diamond back into graphite,” said Jena. “This will be similar.”
Publishing in Proceedings of the National Academy of Sciences,
the team reports that while graphene is a strong conductor of
electricity, penta-graphene is semiconductor, which means it’s not as
good at carrying an electric current without dissipating a lot of power.
But it manages to retain this property no matter how you bend and twist
When you take graphene and roll it up, you make what is called a carbon nanotube, which can be metallic or semiconducting,” says Jena. “Penta-graphene, when you roll it up, will also make a nanotube, but it is always semiconducting.”
The team also found that penta-graphene stretches in really bizarre ways, thanks to a rare property known as Negative Poisson’s Ratio.
This means that the way its molecular bonds are hinged and oriented
ensure that when it’s stretched from either end, not only do those ends
expends, but its width will also increase. So, it basically becomes
fatter, not skinnier, when stretched at the end. 
“If you stretch graphene, it will expand along the direction it is stretched, but contract along the perpendicular direction.” said Wang. “However, if you stretch penta-graphene, it will expand in both directions.”
The team is now going to work on synthesising a physical layer of
penta-graphene, so they can start putting this new carbon variant to the
test. “Once you make it, it [will be] very stable. So the question
becomes, how do you make it?” says Jena.
“We have some ideas. Right now, the project is theoretical. It’s based
on computer modelling, but we believe in this prediction quite strongly.
And once you make it, it will open up an entirely new branch of carbon
science. Two-dimensional carbon made completely of pentagons has never
been known.”
Source: Phys.org


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