Technological jewel: Graphene turns superfine daily

Graphene and diamond are both materials made entirely of carbon, but can the carbon monoatomic sheet be converted directly into a diamond sheet?

The positive answer to this question, which has been asked for a long time by material scientists, was given by Pavel Bakharev and colleagues from the Institute of Basic Sciences of South Korea.

The team developed a method for chemically converting a double-layer graphene sheet to the finest possible diamond-like material under moderate temperature and pressure and temperature conditions.

This extremely strong but flexible thin diamond film is also a tailored semiconductor for industrial nano-optic and nanoelectronic applications. It may serve as a platform for micro and nano-electromechanical systems, but it was still too difficult to manufacture to make this and other applications possible, such as a dreamed diamond electronics.

Diamond

What distinguishes the diamond from graphene is the configuration of the bonds between carbon atoms. In diamonds, carbon atoms are strongly bonded in all directions, creating an extremely hard material with extraordinary electrical, thermal, optical and chemical properties. In pencil and lubricant graphite, carbon atoms are organized as a stack of sheets, each individual sheet being graphene.

On each individual sheet, graphene is formed by strong carbon-carbon (C-C) bonds, but the weak bonds between the sheets are easily broken and partly explain why the pencil tip is so soft. The creation of strong bonds between graphene layers forms a 2D material, similar to diamond thin films, known as diamond, with many technologically interesting features.

Attempts to produce the material artificially have so far attempted to mimic the very high temperature and pressure processes in which diamonds are formed within the earth.

Bahkarev has developed a technique consisting of the exposure of graphene bilayers to an atmosphere of fluor (F), more specifically, xenon difluoride vapors (XeF2). The result is large areas of F diamano, or monolayer fluorinated diamond, a diamond-like material with interlayer bonds and outside fluorine atoms – all without requiring high pressures.

“This simple method of fluorination works at room temperature and under low pressure, without the use of plasma or any gas activation mechanism, thus reducing the possibility of defects,” said Bahkarev.

Another advantage is that F-diamano can be easily detached from the metal surface (CuNi) where it is manufactured. This, coupled with the large sample manufacturing that the technique allows, will facilitate material testing for practical use.

 Source: Technological Innovation