Nanotechnology makes clean, efficient conductor

By Maggie Fox, Health and Science Editor

WASHINGTON (Reuters) - By crushing a widely used semiconductor into nanoparticles, researchers said on Thursday they have created a compound that could lead to cleaner, more efficient refrigerators, solar power plants and other devices.

The crushed material makes it possible to conduct electricity without conducting so much heat, solving a problem that has baffled engineers for 50 years.

Writing in the journal Science, the teams at the Massachusetts Institute of Technology and Boston College said their method provides a cheap way to achieve a major increase in thermoelectric efficiency.

"It conducts 40 percent less heat," Boston College physicist Zhifeng Ren said in a telephone interview.

"In order to achieve that 40 percent less heat conduction you need to have the grains smaller so that you have more blocks to the heat flow."

Smaller grains of the conducting material -- in this case bismuth antimony telluride -- scatter and redirect the heat, making a compound that can be used either for cooling or to generate electricity.

"These thermoelectric materials are already used in many applications but this better material can have a bigger impact," added Gang Chen, a professor of mechanical engineering at MIT who also worked on the study.

The new material could have applications in solar energy, refrigeration, exhaust systems and even in more prosaic applications.