A 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 mechanical properties 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.”