Thursday, May 26, 2022

Graphene is both 3D and 2D material, study

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

Usually, Graphene is considered as ‘Wonder Material’ as it has the highest known thermal and electrical conductivity. It is stronger than steel, light, flexible, and transparent. The material has various applications such as barrier against mosquito bites.

In this study, scientists from the Queen Mary University of London have solved two fundamental questions: to what extent is graphene graphite, and what is the actual thickness of Graphene?

For the first-ever time, scientists obtained unambiguous Raman spectra from unsupported monolayer graphene under pressure. The data was then used to quantify the out-of-plane stiffness of monolayer graphene, which is hard to define due to its 2D nature.

The outcomes indicated a first physically meaningful out-of-plane stiffness of monolayer graphene, and find it to be consistent with that of graphite.

Surprisingly, scientists found that 2D Graphene, which is a single flat layer of carbon atoms arranged in a honeycomb structure, has many of the same mechanical properties as 3-D graphite.

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. Thus, it is reasonable to consider the thickness of Graphene as 0.34 nm.

Dr. Yiwei Sun, the lead author of the study from the 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 a 3-D material, albeit with a minimal 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 disulfide. In that sense, 2-D materials are all 3-D.”

The study is published in the journal Physical Review Letters.


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