Converting Heat Into Electricity
Researchers have created a new type of thermoelectric material that is twice as efficient as any existing analogues.
Thermoelectric materials can convert heat into electricity. This is due to the fact that in the presence of a temperature difference between the two ends, an electric voltage arises in them and charged particles begin to move. In this case, the amount of generated electricity depends on the dimensionless figure of merit (ZT), and the higher it is, the more efficient the conversion.
For the best thermoelectrics today, this indicator is at the level of 2.5-2.8. However, a team of scientists from the Vienna University of Technology has presented a new material with a ZT value of 5-6. It is a silicon crystal coated with a thin layer of iron, vanadium, tungsten and aluminum.
An optimal thermoelectric material should demonstrate a strong Seebeck effect, conduct electricity well, but at the same time be a poor heat conductor. Combining the latter two is challenging because they are usually closely related..
In a pure combination of iron, vanadium, tungsten and aluminum, atoms are distributed evenly in a face-centered cubic lattice, that is, there is always the same distance between two particles of each metal. However, when a layer of this material is deposited on silicon, its structure changes, and the arrangement of atoms becomes random..
Such distribution features change the electronic structure of the material, due to which the current passes through it in a special way, without dissipating. In this case, irregularities in the crystal structure worsen the thermal conductivity, which enhances the thermoelectric effect.
According to the scientists themselves, although a thin layer of the new material will not be able to generate much energy, it will be enough to power sensors and small electronic devices. They believe the design has great potential for IoT production networks by eliminating wires..
Recall that earlier a team of engineers turned a piece of wood into a flexible membrane that converts heat energy into electricity, even with slight temperature changes.
text: Ilya Bauer, photo: TU Wien