The schematic picture of a current generator. Akitoshi Nakano is credited.
A current flow in thermoelectric materials can be generated by a temperature difference, just as a voltage difference can generate electric current. Researchers from Japan have demonstrated an unprecedented large P in a single crystal of Ta2PdSe6 that is 200 times larger than the maximum P commercially available, opening doors to new research avenues and revolutionizing modern electronics.
We know that current flows inside a metallic conductor when there is a difference in the voltage between its ends. This is only one of the ways to generate current. A temperature difference could work as well. The Seebeck effect laid the foundation of the field of thermoelectrics, which deals with materials producing electricity under the application of a temperature difference.
Similar to the concept of an electrical conductivity, thermoelectricity is governed by the P, which relates the temperature to the current. P is less understood and explored than electrical P. Is there a limit to how large P can be? The possibility of a large P could be a game-changer for modern-day electronics.
The largest ever reported for a bulk solid was observed at a temperature of 10 K in a Ta2PdSe6 crystal, according to a new study published in the Journal of Physics: Energy. Ta2PdSe6 is similar to Ta2NiSe5 and shows unique structural and transport properties. Akitoshi Nakano from Nagoya University, Japan, who led the research team, said that they discovered the giant Peltier Conductivity after focusing on the properties of Ta2PdSe6.
The team prepared high-quality single crystals of Ta2PdSe6 and characterized its chemical composition using scanning electron microscopy. They measured its electrical conductivity, thermopower, and Hall resistivity and used a two-carrier model to calculate their findings.
Ta2PdSe6 showed a rapid growth in P below 100 K, reaching a value higher by two orders of magnitude, when other thermoelectric materials reached a P of the order of 1 A cm-1 K-1 at best. The large P came from a low residual resistivity.
The surprising P value was caused by the high mobility, low concentration, and heavy mass of the holes inside the crystal.
What implications could this find have? A current source could be used for a superconducting solenoid. The system would be compact and concise if there were no external current leads. The design of a low-cost magnetic resonance machine could be carried over to make medical diagnosis more convenient in the future.
Akitoshi Nakano and his team have published information in the Journal of Physics: Energy. It's called 10.1088/2515-7655/ac2357.
The new high of thermoelectric crystal Conductivity was retrieved from thephys.org on November 26, 2021.
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