Scientists in Japan Build Harder Diamond Using New Method

Diamonds aren't the only configurations made up of carbon atoms, which are called allotropes. There's lead, whcih we use in our day to day pencils, as well as carbon nanotubes. The way an allotrope becomes hard depends largely on the way its atoms bond together.

In regular diamonds, each carbon atom forms a bond with four neighbors.

What the University of Tsukuba researchers did was to see what would happen if carbon atoms were formed in a more complex structure. 

So, the team used a computational method called density functional theory (DFT) to calculate the most stable atomic configuration. Through this method, the researchers discovered that the Young's modulus, a measure of hardness, of pentadiamond was predicted to be nearly 1,700 GPa, compared with a regular diamond with 1,200 GPa.

"Not only is pentadiamond harder than conventional diamond, its density is much lower, equal to that of graphite," explained co-author Professor Mina Maruyama.

"This work shows the power of designing materials ab initio. In addition to industrial cutting and drilling uses, pentadiamonds might be used in place of diamond anvil cells currently used in scientific research to recreate the extreme pressure inside planets" said senior co-author Professor Susumu Okada.