CHESTNUT HILL, MA (1/25/11) -- Researchers from Boston College, MIT, Clemson and Virginia have used nanotechnology to achieve a 60-90 percent increase in the thermoelectric figure of merit of p-type half-Heusler, a common bulk semiconductor compound, the team reported in the American Chemical Society journal Nano Letters.
The dramatic increase in the figure of merit, used to measure a material's relative thermoelectric performance, could pave the way for a new generation of products from car exhaust systems and power plants to solar power technology that that runs cleaner, according to co-author Yan Xiao, a researcher in the Department of Physics at Boston College.
The team registered improvement in half-Heusler, which has been under study for its thermal stability, mechanical sturdiness, non-toxicity and low cost. However, the application of half-Heusler has been limited because of its poor thermoelectric performance: it previously registered a peak figure of merit of approximately 0.5 at 700 degrees Celsius for bulk ingots.
Xiao, working with BC Professor of Physics Zhifeng Ren and MIT's Soderberg Professor of Power Engineering Gang Chen, said the team produced an increase in the figure of merit value of p-type half-Heusler to 0.8 at 700 degrees Celsius. Moreover, the groups' material preparation methods proved to save time and expense compared with conventional methods.
"This method is low cost and can be scaled for mass production," Ren said. "This represents an exciting opportunity to improve the performance of thermoelectric materials in a cost-effective manner."
The researchers obtained their results by first forming alloyed ingots using arc melting technique and then creating nanoscale powders by ball milling the ingots and finally obtaining dense bulk by hot pressing. Transport property measurements together with microstructure studies on the nanostructured samples, in comparison with that of bulk i
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