Transport and mechanical properties of Yb-filled skutterudites

Abstract

A series of Yb-filled skutterudites were produced and powder samples consolidated using spark plasma sintering (SPS). The effect of different heating cycles on the resulting transport properties of the consolidated samples was explored. Specifically, the effect of sample uniformity on the electrical and thermal transport properties was explored. In addition to the optimal Yb-filling fraction, other factors, such as heating profiles and sintering conditions, were found to play a pivotal role in the performance of these materials. Large quantities of Yb-filled skutterudite material can be generated with high purity and uniformity. Resonant ultrasound spectroscopy was used to determine the elastic modulus and Poisson's ratio. Fracture strength was measured for 12 specimens and, taken with information obtained from resonant ultrasound spectroscopy and from thermal expansion and thermal transport characteristics, the thermal shock resistance parameter was evaluated. These parameters will be important for the engineering of thermoelectric modules based on skutterudite materials.

Keywords:

• electron microscopy
• materials preparation
• mechanical property evaluation
• thermal transport
• thermoelectric power

Acknowledgements

JRS, XS, and JY would like to thank J. Herbst and M. Verbrugge for their continued support and encouragement. AAW thanks S. Waters, K. Strong Jr., and T. Kirkland for their assistance with the dilatometry, elastic property measurements, and strength testing, respectively. Elemental analysis provided by Richard Waldo Powder X-ray diffraction by Richard Speer Jr. Transmission electron microscopy was provided by Michael Balogh. This work is supported by GM and by DOE under corporate agreement DE-FC26-04 NT42 278. This work was also supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Transportation Technologies, as part of the High Temperature Materials Laboratory User Program at Oak Ridge National Laboratory by the UT-Battelle LLC, for the Department of Energy under contract DE-AC05000 OR22725.