Filled skutterudite

Figure 7.6. A filled. skutterudite antimonide crystal structure. A transition niclal atom (Fc or Co) at the centre of each octahedron is bonded to antimony atoms at each corner. The rare earth atoms (small spheres) are located in cages made by eight octahedra. The large thermal motion of rattling of the rare earth atoms in their cages is believed be responsible for the strikingly low thermal conductivity of these materials (Sales 1997).

Ce filled skutterudites 12 14.3. Future of filled skutterudites as thermo- ... 

Fig. 3. Model of the filled skutterudite structure. The transition metal atoms (Fe, Ru, or Os - small light blue...

Fig. 4. Model of filled skutterudite structure that emphasizes the pnicogen-pnicogen bonding that results in nearly square pnicogen rings. The transition metal atoms (small white spheres) form a simple cubic lattice as shown. The lines connecting the transition metal atoms have been added for clarity and do not correspond to a chemical bond. The only chemical bonds shown in this model are those that form the pnicogen rings. The lanthanide atoms (large dark spheres) occupy the two voids without a pnicogen ring.

I lcurial et al., 1996). This discovery greatly increased the interest in these materials for thermoelectric applications. In addition to the stoichiometric filled skutterudite compounds of the form RM4X12, a large number of related alloys were also investigated as possible thermoelectric materials. Most of the research on lanthanide skutterudites in the context of thermoelectric applications has been reviewed recently by Uher (2001), Nolas et al. (1999), and Sales (1998) and hence only a brief summary of the thermoelectric research will be highlighted in this section. 

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