Skutterudite Derivatives: A Fundamental Investigation with Potential for Thermoelectric Applications

Thermoelectric devices allow for direct conversion of heat into electricity as well as solid-state refrigeration. The skutterudite family of compounds continues to be of considerable interest both scientifically and technologically due to their unique physical properties, in particular as promising thermoelectric materials. In this thesis, the basic thermoelectric phenomena and some background history on skutterudites will be reviewed. Rhombohedral derivatives of the cubic skutterudite CoSb3, namely Co4-xFexGe6Se6 with x=0, 1, 1.5 (p-type) and rare-earth filled Ce0.13Co4Ge6Se6 and Yb0.14Co4Ge6Se6 (n-type), were synthesized and their synthesis and low temperature transport properties will be discussed. Reitveld refinement and elemental analysis were used to identify the structure and stoichiometry of these compositions. Both Fe substitution and rare-earth filling reduced the thermal conductivity compared with Co4Ge6Se6 skutterudite derivative. In addition the electrical and thermal properties of these compounds are greatly affected by doping. This fundamental investigation reveals new insight and is intended as part of the continuing effort to explore different skutterudite compositions and structure types for potential thermoelectric applications