| Abstract |
| Partially La/Pr-double-filled and Co-substituted (La1-zPrz)0.8Fe4-xCoxSb12 skutterudites were synthesized by encapsulated melting and vacuum hot pressing. (La,Pr)Sb2 phases were not formed because the partial filling did not exceed the filling fraction limit, and the amount of secondary phase FeSb2 also decreased as the Co content increased. Electrical conductivity decreased with increasing Pr filling and Co substitution because of the decreased carrier concentration. The (La0.75Pr0.25)0.8Fe4Sb12 skutterudite, which was not charge-compensated with Co, showed the highest electrical conductivity of 2.44 × 105 Sm-1 at 323 K. In contrast, the Seebeck coefficient increased with increased Co substitution, and the (La0.25Pr0.75)0.8Fe3CoSb12 exhibited the maximum Seebeck coefficient of 168.2 μVK-1 at 723 K; (La0.75Pr0.25)0.8Fe3.5Co0.5Sb12 exhibited the highest power factor of 2.67 mW m-1 K-2 at 823 K; and (La0.25Pr0.75)0.8Fe3CoSb12 exhibited the lowest thermal conductivity of 2.09 W m-1 K-1 at 523 K. Consequently, (La0.25Pr0.75)0.8Fe3.5Co0.5Sb12 exhibited the maximum dimensionless figure of merit, ZT = 0.79 at 723 K.
(Received August 13, 2018; Accepted August 27; 2018) |
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| Key Words |
| thermoelectric, skutterudite, partial double filling, charge compensation |
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