Thermoelectrics convert heat into electricity and are found primarily in devices for power generation and refrigeration. Like all solids, their structure is usually either crystalline, with an orderly atomic structure, or amorphous, where the atoms are randomly ordered. The new material, developed at South Carolina’s Clemson University in collaboration with researchers in China and Denmark, combines both crystalline and amorphous qualities and could be a ‘potentially paradigm-shifting high-performance thermoelectric compound’.
"Our material is a unique hybrid atomic structure with half being crystalline and half amorphous," said Jian He, an associate professor at Clemson’s College of Science's Department of Physics and Astronomy. "If you have a unique or peculiar atomic structure, you would expect to see very unusual properties because properties follow structure."
The researchers created their hybrid material by mixing elements in the same group on the periodic table but with different atomic sizes. As described in the academic journal Joule, the team used the atomic size mismatches between sulphur and tellurium and between copper and silver to create a new compound (Cu1-xAgx)2(Te1-ySy) in which the crystalline and amorphous sublattices intertwine into a one-of-a-kind crystal-amorphicity duality.
"The new material performs well, but more important than that is how it achieves that level of performance," said He. "Traditionally, thermoelectric materials are crystals. Our material is not pure crystal, and we show we can achieve the same level of performance with a material with a new atomic structure."
While the new compound is said to have exhibited excellent thermoelectric performance, the implications may not be seen for some time, with the researchers anticipating applications to take between 10 and 20 years to evolve.
"They definitely can do something current thermoelectric materials cannot do, but not now," He said. "However, the future of this research is bright."
In addition to He, the research involved scientists from Shanghai Jiaotong University, Shanghai Institute of Ceramics and SUSTech in China, and Aarhus University in Denmark.