Nano-engineering boosts efficiency of materials that convert waste heat to electrical energy

May 30, 2013

High-performance thermoelectric materials that convert waste heat to electricity could one day be a source of more sustainable power. But they need to be a lot more efficient before they could be effective on a broad scale in places like power plants or military bases, researchers say.

A University of Michigan researcher has taken a step toward that goal. By engineering a at the level of its individual atoms, Pierre Ferdinand P. Poudeu, assistant professor of and engineering, has boosted its ability to convert heat into power by 200 percent and its by 43 percent. That's an important combination. Improving both of these figures at the same time is a major challenge for researchers working in the field.

The material Poudeu used is an alloy of titanium, zirconium, nickel and tin. While it's not a particularly effective thermoelectric material at this point, Poudeu says it made a good testbed.

"This concept is new and exciting," Poudeu said. "We think it can be adapted to other materials as well and pave the way for improved intended for high-performance energy conversion applications.

"If we want to build generators that convert to electricity and that are capable of replacing current technology, thermoelectric materials with much higher efficiency need to be discovered. We'll have to about double the efficiency typically achieved today."

Poudeu says his nano-engineering approach could achieve those gains if it can be used in current leading candidate thermoelectric materials systems.

His strategy differs from common chemical-based techniques such as doping, in which researchers add impurities to a host material to alter its and make it more conductive. In thermoelectric materials, doping can work against itself, however, because the impurities can hamper the heat-to-.

Rather than add impurities, which are typically foreign chemical elements, Poudeu introduced additional individual atoms of nickel—one of the elements already in the material. The nickel atoms found their way into the crystal structure of the and filled out a small fraction of its vacant atomic sites. They formed what Poudeu describes as quantum dots—nanoscale structures that follow the laws of quantum, rather than classical, physics.

The structures are so small, you'd need to line up a million just to be able to see them without a microscope, Poudeu says.

The quantum dots act as traps, blocking low-energy electrons from reducing the conversion efficiency, while creating a pathway for higher energy electrons to pass through as electric current. The addition of the quantum dots into a bulk semiconductor results in a new material with a distinct electronic structure, Poudeu says.

The paper is titled "Large Enhancements of Thermopower and Carrier Mobility in Quantum Dot Engineered Bulk Semiconductors." It is published online in the Journal of the American Chemical Society and will appear in a forthcoming print edition.

Explore further: Cooling with the coldest matter in the world

More information: pubs.acs.org/doi/full/10.1021/ja311059m

Related Stories

Energy savings—easy as dirt, heat, pressure

Nov 27, 2012

(Phys.org)—By using common materials found pretty much anywhere there is dirt, a team of Michigan State University researchers have developed a new thermoelectric material.

Fujifilm breaks record with thermoelectric material

Feb 07, 2013

(Phys.org)—Photographic film maker Fujifilm has been busy this year at the Nanotech 2013 conference being held in Tokyo. First came news of bendable/roll up speakers. Now the company is showing off a new thermoelectric ...

Recommended for you

Cooling with the coldest matter in the world

Nov 24, 2014

Physicists at the University of Basel have developed a new cooling technique for mechanical quantum systems. Using an ultracold atomic gas, the vibrations of a membrane were cooled down to less than 1 degree ...

Magnetic fields and lasers elicit graphene secret

Nov 24, 2014

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) have studied the dynamics of electrons from the "wonder material" graphene in a magnetic field for the first time. This led to the discovery of ...

New 2-D quantum materials for nanoelectronics

Nov 21, 2014

Researchers at MIT say they have carried out a theoretical analysis showing that a family of two-dimensional materials exhibits exotic quantum properties that may enable a new type of nanoscale electronics.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.