Skutterudites for thermoelectric applications

Thermoelectric generators and cooling devices present several advantages compared to other energy conversion technologies: they are reliable, can operate unattended in hostile environments, and are also environmentally friendly. However, their application has been limited up to now because of the relatively low conversion efficiency of traditional thermoelectric materials used in the devices. New more efficient materials are needed. A new class of semiconducting materials was identified at JPL a few years ago and the study of the properties of these materials for thermoelectric and other applications has been subject to a growing interest. Recent findings on the physical-chemical and transport properties of skutterudite materials are reviewed. Results obtained on binary compounds showed that their lattice thermal conductivity is too high to achieve high thermoelectric figures of merit. Several approaches have been recently proposed to decrease the lattice thermal conductivity of skutterudite materials. They are described and illustrated by recent experimental results. It is shown that low thermal conductivity can be achieved and high ZT values are possible for skutterudites.