Thermoelectric Properties in Nanostructured p-type Skutterudites

Skutterudites are good examples of phonon glass electron crystal (PGEC), which is proposed to be one of the most desirable materials to maximize the thermoelectric figure of merit. The skutterudite structure has two voids in each unit cell that are large enough to accommodate a variety of atoms, such as La, Ce, Nd, Sm, Yb, etc. These atomic void-fillers rattle about in their oversized cages, thereby drastically reducing thermal conductivity and maximizing ZT. My work on p-type skutterudites is based on compounds of a general formula RFe$_{3.5 }$Co$_{0.5}$Sb$_{12}$ where R stands for a void filler. Besides the influence of rattling of the void fillers, thermal conductivity can be further depressed by the increased phonon scattering at the increased grain boundaries due to nano size grains.