December 14, 2011

New Elemental Cookbook Guides Efficient Thermoelectric Combinations

A materials genome repository developed by Duke University engineers will allow scientists to stop using trail-and-error methods for combining different elements to create the most efficient alloys for a promising method of producing electricity.

These thermoelectric materials produce electricity by taking advantage of temperature differences and are currently being used in such applications as deep space satellites to campsite coolers. In the past, scientists have not had a rational basis for combining different elements to produce these energy-producing materials.

The project developed by the Duke engineers covers thousands of compounds, and provides detailed “recipes” for creating most efficient combinations for a particular purpose, much like hardware stores mix different colors to achieve the desired result. The database is free and open to all (aflowlib.org).

“We have calculated the thermoelectric properties of more than 2,500 compounds and have calculated all their energy potentials in order to come up with the best candidates for combining them in the most efficient ways,” said Stefano Curtarolo, associate professor of mechanical engineering and materials sciences and physics at Duke’s Pratt School of Engineering. “Scientists will now have a more rational basis when they decide which elements to combine for their thermoelectric devices.”

Physical Review X - Assessing the Thermoelectric Properties of Sintered Compounds via High-Throughput Ab-Initio Calculations




A thermoelectric device takes advantage of temperature differences on opposite sides of a material – the greater the temperature difference, the greater energy potential. Different material combinations may be a more efficient method of turning these temperature differences into power, according to Shidong Wang, a post-doctoral fellow in Curtarolo’s lab and first author of the paper.

Thermoelectric materials can be created by combining powdered forms of different elements under high temperatures – a process known as sintering. Not only does the new program provide the recipes, but it does so for the extremely small versions of the particular elements, known as nanoparticles. Because of their miniscule size and higher surface areas, nanoparticles have properties unlike their bulk counterparts.

“Having this repository could change the way we produce thermoelectric materials,” Wang said. “With the current trial-and-error method, we may not be obtaining the most efficient combinations of materials. Now we have a theoretical background, or set of rules, for many of the combinations we now have. The approach can be used to tackle many other clean energy related problems.”

Several thousand compounds from the Inorganic Crystal Structure Database have been considered as nanograined, sintered-powder thermoelectrics with the high-throughput ab-initio AFLOW framework. Regression analysis unveils that the power factor is positively correlated with both the electronic band gap and the carrier effective mass, and that the probability of having large thermoelectric power factors increases with the increasing number of atoms per primitive cell. Avenues for further investigation are revealed by this work. These avenues include the role of experimental and theoretical databases in the development of novel materials.

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