High performance p-type segmented leg of misfit-layered cobaltite and half-Heusler alloy
In this study, a segmented p-type leg of doped misfit-layered cobaltite Ca_(2.8)Lu_(0.15)Ag_(0.05)Co_4O_(9+δ) and half-Heusler Ti_(0.3)Zr_(0.35)Hf_(0.35)CoSb_(0.8)Sn_(0.2) alloy was fabricated and characterized. The thermoelectric properties of single components, segmented leg, and the electrical contact resistance of the joint part were measured as a function of temperature. The output power generation characteristics of segmented legs were characterized in air under various temperature gradients, ΔT, with the hot side temperature up to 1153 K. At ΔT ≈ 756 K, the maximum conversion efficiency reached a value of ∼5%, which is about 65% of that expected from the materials without parasitic losses. The long-term stability investigation for two weeks at the hot and cold side temperatures of 1153/397 K shows that the segmented leg has good durability as a result of stable and low electrical resistance contacts.
© 2015 Elsevier Ltd. Received 28 July 2014; Accepted 30 March 2015; Available online 21 April 2015. BB gratefully acknowledges the financial support by the DFG Priority Program 1386 ''Nanostructured Thermoelectric Materials'' under proposal BA 4171/2-2. NVN acknowledges the support by the NAFOSTED grant under proposal 103.02 2011.10. The authors would like to thank the Programme Commission on Sustainable Energy and Environment, The Danish Council for Strategic Research for sponsoring the ''Oxide thermoelectrics for effective power generation from waste heat'' (OTE-POWER) (No. 10-093971) as well as the ''CTEC - Center for Thermoelectric Energy Conversion'' (No. 1305-00002B) projects. The authors also thank the European Commission for sponsoring the NanoCaTe (FP7-NMP No. 604647) project.