Graphene is 3-D as well as 2-D

Graphene is 3D as well as 2D
The Queen Mary research shows that graphene is 3D as well as 2D. Credit: Yiwei Sun

Graphene is actually a 3-D material as well as a 2-D material, according to a new study from Queen Mary University of London.

Realising that it is a 3-D material is important for understanding its mechanical properties and for developing novel graphene-based devices.

Often hailed as a 'wonder material', graphene has the highest known thermal and electrical conductivity, is stronger than steel, light, flexible and transparent. Its uses are wide-ranging and recently it has been shown it could even act as a barrier against .

In this study, published in the journal Physical Review Letters, the researchers asked two fundamental questions: to what extent is graphene graphite, and what is the true thickness of graphene?

To their surprise, they found that 2-D graphene, which is a flat single layer of carbon atoms arranged in a honeycomb structure, has many of the same as 3-D graphite, which is a naturally occurring form of carbon made up from a very weak stack of many layers of graphene.

They show that graphene shares a similar resistance to compression as graphite and that it is significantly thicker than is widely believed.

If the thickness of a block of graphite 100 layers thick is measured, the thickness of a single graphene layer is simply the thickness of the graphene block divided by 100. Therefore, it is reasonable to consider the thickness of graphene as 0.34 nm.

Dr. Yiwei Sun, lead author of the study from Queen Mary University of London, said: "Graphene owes its thickness to an array of chemical bonds sticking out above and below the 2-D plane of carbon atoms. Hence graphene is really a 3-D material, albeit with a very small thickness.

"By applying conventional 3-D theory, which has been used for around 400 years, to 2-D materials such as graphene, which have been known for 15 years, we show that similar arguments apply to other so-called 2-D materials, such as boron nitride and molybdenum disulphide. In that sense, 2-D materials are actually all 3-D."

Graphene is often called the world's first two-dimensional material. It was discovered in 2004 by peeling off flakes from bulk (used in pencil leads and lubricants) using sticky tape.

It is regarded as part of a new class of 2-D materials and it is currently modelled by scientists as a sheet of atoms with very little depth, hence the name 2-D material.


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More information: '3D strain in 2D materials: to what extent is monolayer graphene graphite?'. Y. W. Sun, W. Liu, I. Hernandez, J. Gonzalez, F. Rodriguez, D. J. Dunstan, and C. J. Humphreys. Physical Review Letters, 2019.
Journal information: Physical Review Letters

Citation: Graphene is 3-D as well as 2-D (2019, September 23) retrieved 20 October 2019 from https://phys.org/news/2019-09-graphene-d.html
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Sep 23, 2019
"By applying conventional 3-D theory, which has been used for around 400 years, to 2-D materials such as graphene, which have been known for 15 years, we show that similar arguments apply to other so-called 2-D materials, such as boron nitride and molybdenum disulphide. In that sense, 2-D materials are actually all 3-D."


Somehow this statement reminds me of the humorous little blurbs in Kerbal Space Program...

Sep 23, 2019
Hmmmm, moly and graphite are excellent lubricants precisely because of the slippage of the layers over one another with very low friction. I wonder how that plays into this. I wouldn't know about boron nitride; I don't really do much with high temperature components. And that's what it's mostly good for.

Sep 23, 2019
On another note, @axe, good to see you around again. Don't mellow too much; we've got another titch of brolls agitating about the climate summit.

Sep 23, 2019
I don't quite understand the point of this study. Graphene, molybdenum disulphide, phosphorene, silicene etc etc are all called "2-D materials" as a figure of speech, not in a literal sense. It has always been known that they are not *really* 2-D. 2-D surfaces exist only in pure math, since they actually mean a thickness of zero.

"But what about the real world?", one might ask. "What is the thinnest surface that's physically possible?" That would be a surface with a thickness of one Planck length (1.6 x 10^-35 m). For all intents and purposes that would be a truly two-dimensional surface, because that's the smallest size that's allowed by the laws of physics.

In comparison a single graphene layer has a humongous thickness, since we are talking about a size 10^-20 times smaller than a proton. Even electrons and quarks are comparatively macroscopic.

Sep 24, 2019
Hmmmm, moly and graphite are excellent lubricants precisely because of the slippage of the layers over one another with very low friction. I wonder how that plays into this. I wouldn't know about boron nitride; I don't really do much with high temperature components. And that's what it's mostly good for.

So, good to see @DaSchitebo, the lubricant expert, finally in his domain.

Sep 24, 2019
I don't quite understand the point of this study. Graphene, molybdenum disulphide, phosphorene, silicene etc etc are all called "2-D materials" as a figure of speech, not in a literal sense. It has always been known that they are not *really* 2-D. 2-D surfaces exist only in pure math, since they actually mean a thickness of zero.

That's exactly the thing. As nothing real can truly be 2-D, a material is considered to be 2-D if it has the properties of 2-D material. Likewise, quantum dots are 1-D materials because the properties of the dots cannot be explained without the use of quantum mechanics.

Sep 24, 2019
On another note, @axe, good to see you around again. Don't mellow too much; we've got another titch of brolls agitating about the climate summit.


Oh, I'm always around skimming articles, I just don't post much anymore. I'm spending probably 12-14 hours a day on research and I'm usually too exhausted to engage with the toxic atmosphere over here.

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