January 2019: Dr Claudio Cazorla "Polymorphism of bulk boron nitride"
"Computers uncover a key relationship between pencils and diamonds"
Diamonds are made from carbon atoms. So too is graphite. The very big differences between these two materials come entirely from the way the carbon atoms are arranged. Scientists know that the graphite form of carbon is more stable than the diamond form. Only at high pressures (like deep in diamond seams) do they swap.
Carbon has two chemical neighbours: boron and nitrogen. Together, these neighbours act very much like carbon on its own. The resulting boron-nitride compound also comes in diamond and graphite forms, which are like carbon in some ways (diamond boron-nitride is almost as hard as a regular diamond), but dramatically different in other ways (boron-nitride heats up at a different rate).
Recent work from Claudio Cazorla (UNSW) and Tim Gould (Griffith University) has shown that, unlike carbon, the diamond structure of boron nitride is more stable than the pencil structure. But, at the temperature of a long black coffee the graphite form becomes more stable, like carbon.
Read the full paper, as published in Science Advances (Vol. 5, no. 1, eaau5832).