Diamond technique could help unlock new material properties

Using a novel form of diamond that is even harder and more durable than the conventional gemstones, a team from the universities of Antwerp, Chicago and Bayreuth (in Germany) has developed apparatus that can subject solid materials to pressures of 640GPa — higher than those found at the centre of the Earth.

High pressures can cause materials to behave strangely: metals can become insulators, non-metals can become superconducting and chemical properties can change. Materials scientists are keen to study these transformations, while Earth scientists and cosmologists use these techniques to investigate the behaviour of materials at the centre of planets. Engineers can also use high pressure to determine how materials behave under extreme shockwaves.

These high pressures are generally achieved using diamond anvil cells, where very small samples are squashed between the surfaces of gem-quality diamonds. But diamonds are limited for this purpose because their crystalline structure means they have inherent planes along which they can break. The upper limit of anvil cells is 320–360GPa, which is around the pressure of the Earth’s core.