Scientists have created synthetic diamonds that are harder and more durable than natural diamonds.
At the Yanshan University, researchers have enhanced fake diamonds by creating “nanotwinned diamonds (nt-diamonds)”, according to Nature magazine.
The team explained that previous attempts at creating harder synthetic diamonds using the nanotwinned method failed, as the carbon precursors such as graphite, amorphous carbon, and glassy carbon had not worked.
However “recent success in synthesizing nanotwinned cubic boron nitride (nt-cBN) with a twin thickness down to ~3.8 nm makes it feasible to simultaneously achieve smaller nanosize, ultrahardness and superior thermal stability,” the researchers stated.
Prior to this new research nanograined diamond grain structures were limited to between 10 and 30nm, and had degraded thermal stability compared to natural diamonds.
Now the researchers have created the “direct synthesis of nt-diamond with an average twin thickness of ~5nm, using a precursor of onion carbon nanoparticles at high pressure and high temperature, and the observation of a new monoclinic crystalline form of diamond coexisting with nt-diamond”.
They were created by heating carbon onions – which are fullerene spheres contained within one another – to temperatures of up 2000 degrees Celsius and 25GPa.
This method created a diamond of extreme hardness of around 200GPa with more stability at temperatures of close to 1000 degrees Celsius, which is more than 200 degrees higher than natural diamonds.
“The pure synthetic bulk nt-diamond material shows unprecedented hardness and thermal stability, with Vickers hardness up to ~200GPa ,” the group stated.
These new developments will be used in making industrial tools and scientific instruments that are manufactured at higher temperatures.