Researchers at Northwestern Univ. have placed nanocrystals of rock
salt into lead telluride, creating a material that can harness electricity from
heat-generating items such as vehicle exhaust systems, industrial processes and
equipment, and sun light more efficiently than scientists have seen in the
past.
The material exhibits a
high thermoelectric figure of merit that is expected to enable 14% of heat
waste to electricity, a scientific first. Chemists, physicists, and material
scientists at Northwestern collaborated to develop the material. The results of
the study are published by the journal Nature Chemistry.
“It has been known
for 100 years that semiconductors have this property that can harness
electricity,” said Mercouri Kanatzidis, the Charles E. and Emma H.
Morrison Professor of Chemistry in The Weinberg College of Arts and Sciences.
“To make this an efficient process, all you need is the right material,
and we have found a recipe or system to make this material.”
Kanatzidis, co-author
of the study, and his team dispersed nanocrystals of rock salt (SrTe) into the
material lead telluride (PbTe). Past attempts at this kind of nanoscale
inclusion in bulk material have improved the energy conversion efficiency of
lead telluride, but the nano inclusions also increased the scattering of
electrons, which reduced overall conductivity. In this study, the Northwestern
team offers the first example of using nanostructures in lead telluride to reduce
electron scattering and increase the energy conversion efficiency of the
material.
“We can put this
material inside of an inexpensive device with a few electrical wires and attach
it to something like a light bulb,” said Vinayak Dravid, professor of materials
science and engineering at Northwestern’s McCormick School of Engineering and
Applied Science and co-author of the paper. “The device can make the light
bulb more efficient by taking the heat it generates and converting part of the
heat, 10% to 15%, into a more useful energy like electricity.”
The automotive,
chemical, brick, glass, and any industry that uses heat to make products could
make their system more efficient with the use of this scientific breakthrough,
said Kanatzidis, who also has a joint appointment at the Argonne National
Laboratory.
“The energy crisis
and the environment are two major reasons to be excited about this discovery,
but this could just be the beginning,” Dravid said. “These types of
structures may have other implications in the scientific community that we
haven’t thought of yet, in areas such as mechanical behavior and improving
strength or toughness. Hopefully others will pick up this system and use it.”