Skutterudite unicouple characterization for energy harvesting applications

Skutterudites are promising thermoelectric materials because of their high figure of merit, ZT , and good thermomechanical properties. This work reports the effective figure of merit, ZT eff , and the efficiency of skutterudite legs and a unicouple working under a large temperature difference. The p- and n-type legs are fabricated with electrodes sintered directly to the skutterudite during a hot pressing process. CoSi₂is used as the electrode for the n-type skutterudite (Yb_0.35Co₄Sb₁₂) and Co ₂Si for the p-type skutterudite (NdFe_3.5Co _0.5Sb₁₂). A technique is developed to measure the ZT eff of individual legs and the effi- ciency of a unicouple. An ZT eff of 0.74 is determined for the n-type legs operating between 52 and 595°C, and an ZT eff of 0.51 for the p-type legs operating between 77 and 600°C. The efficiency of the p-n unicouple is determined to be 9.1% operating between - 70 and 550°C.