Chinese materials scientists have developed an innovative composite material that combines the high hardness of diamond with the electrical conductivity of graphite, graphene and other carbon materials. These unique composites could be used in a variety of applications where high strength and electrical conductivity are needed, researchers say in a paper published in the journal PNAS.
“Creating materials with high mechanical strength and good electrical conductivity has always been one of the main goals of materials science. “We managed to solve this problem by using nanodiamonds as starting materials to create diamond- and graphene-based composites at moderate temperatures and pressures,” states the publication.
The discovery was made by a team of materials scientists led by Shan Chunxin, a professor at Zhengzhou University in China, while trying to develop a material in which carbon atoms form two different types of bonds, known to chemists as sp2 and sp3 networks. The first type of bond is characteristic of graphite, graphene and other forms of carbon with good electrical conductivity; The second provides high strength to diamond and similar forms of carbon.
Previously, chemists were able to create small pieces of carbon material with such “hybrid” chemical bonds, but all these advances could not be used in industry due to limitations in large-volume production of such materials. Professor Shan Chunxin discovered that these problems can be overcome by using nanodiamonds with a diameter of 5.8 nanometers as the basis of such materials.
Compressing these precious stones at high temperatures (1300-1500 degrees Celsius) to 118 thousand atmospheres of pressure results in the formation of a composite material similar to coal in color and shape. The substance, called “diaphene”, has a hardness comparable to diamond and boron nitride and also has the ability to conduct electricity at the level of pure graphite or graphene.
Further experiments by Professor Shan Chunxin showed that his method makes it possible to obtain large pieces of diaphene, more than a centimeter long, that can withstand heating up to 700 degrees Celsius. Scientists conclude that this opens up the possibility of using diaphene to produce various parts that can conduct current and withstand high mechanical and temperature loads.
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