‘Atomic cage’ material converts waste heat to electricity

Austrian researchers have “grown” an unusual thermoelectric material that converts heat to electric current and has some promising industrial applications

A team of scientists at the Vienna University of Technology in Austria have developed a super-efficient class of material that they claim could one day be used to turn waste industrial heat into useful electrical energy.

According to the team, the material owes its properties to an unusual crystalline structure known as a clathrate, in which magnetic atoms of the rare earth metal cerium are effectively enclosed in tiny cage-like spaces.

‘These clathrates show remarkable thermal properties,’ said Professor Silke Bühler-Paschen, who led the research. ‘We came up with the idea to trap cerium atoms, because their magnetic properties promised particularly interesting kinds of interaction.’

Explaining the thermoelectric behaviour of the material, Bühler-Paschen said: ‘the thermal motion of the electrons in the material depends on the temperature.

On the hot side, there is more thermal motion than on the cold side, so the electrons diffuse towards the colder region. Therefore, a voltage is created between the two sides of the thermoelectric material.’

Using a sophisticated crystal growth technique in a mirror oven, the team incorporated the cerium atoms into the clathrate structures made of barium, silicon and gold.

It is now looking to achieve similar results with lower cost metals such as copper which could make the material more commercially attractive.