Sat. Jan 22nd, 2022

IN "Nature": Bayreuth researchers discover carbon material with unique structure

Structural comparison: crystalline diamond (left) and paracrystalline diamond (right). To the right are units of carbon atoms arranged in a cube shape marked with turquoise, units of carbon atoms arranged in a hexagonal shape are marked in yellow. Irregular structures are marked in red. Credit: Hu Tang.

A team of researchers from China, Germany and the United States has developed a way to create a less fragile diamond. In their paper published in the journal Nature, the group describes their approach to creating a paracrystalline diamond and possible uses for it.

Previous research has shown that diamond is the hardest known material, but it is also fragile – despite their hardness, diamonds can be easily cut or even crushed. This is due to their ordered atomic structure. Researchers have for years tried to synthesize diamonds that retain their hardness but are less fragile. The team is now close to reaching that goal.

Currently, the way to create diamonds is to place a carbon-based material in a vise-like unit where it is heated to very high temperatures while being pressed very hard. In this new effort, scientists have used the same approach to create a less orderly type of diamond, but have added a new twist – the carbon-based material was a batch of fullerenes, also known as buckyballs (carbon atoms arranged in a hollow spherical shape). form). They heated the material to between 900 and 1,300 ° C at pressures of 27 to 30 gigapascals. It is noteworthy that the pressure exerted was much lower than that used to make commercial diamonds. During the treatment, the spheres were forced to collapse and they became transparent paracrystalline diamonds which could be extracted at room temperature.

Skaber en mindre skrøbelig diamant

FIG. 1: Synthesize fully sp3-bound carbon samples at 30 GPa and 1,200–1,600 K for 10 min. Credit: DOI: 10.1038 / s41586-021-04122-w

After making their less ordered diamonds, the researchers looked at them under an electron microscope to learn more about their structure. They also subjected samples to X-ray diffraction and atomist modeling. In doing so, they found out that their diamonds were made of disordered sp3-hybridized carbon, exactly as expected. The goal of creating a less fragile diamond had been achieved. Contrary to the results of another recent effort to synthesize a less fragile diamond, their resulting diamond is not completely amorphous (which would make it a type of glass), theirs is a type of amorphous diamond paracrystal. This means that it has an intermediate order – its atoms are arranged over short distances, but not over long ones. Thus, no atomic plane exists, which means that the diamonds cannot be cut like natural diamonds.


Newly synthesized AM-III carbon is the hardest and strongest amorphous material to date


More information:
Hu Tang et al, Synthesis of paracrystalline diamond, Nature (2021). DOI: 10.1038 / s41586-021-04122-w

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Citation: Creating a less fragile diamond using fullerenes (2021, 28 November) retrieved 28 November 2021 from https://phys.org/news/2021-11-fragile-diamond-fullerenes.html

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