Thermoelectric properties of p-type didymium (DD) based skutterudites DDy(Fe1−xNix)4Sb12 (0.13 ⩽ x ⩽ 0.25, 0.46 ⩽ y ⩽ 0.68)

The thermoelectric properties of ball milled didymium (DD) based skutterudites DDy(Fe1−xNix)4Sb12 skutterudites were studied for 0.13 ⩽ x ⩽ 0.25 and 0.46 ⩽ y ⩽ 0.68 in the temperature range from 300 to 800 K and were compared with those of DDy(Fe1−xNix)4Sb12 with x = 0 of a previous work as well as with their Co-substituted counterparts. Didymium was used as natural double filler (4.76 mass% Pr and 95.24 mass% Nd). The figures of merit ZT of p-type DDy(Fe1−xNix)4Sb12 skutterudites reach ZT ⩾ 1 for the composition range 0.13 ⩽ x ⩽ 0.2 (for x = 0.15 ZT is almost 1.1), however, ZT values rapidly decrease for a higher nickel content. The thermoelectric efficiency with more than 12% is remarkable and similar to the values for DDy(Fe1−xCox)4Sb12 skutterudites.

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► In comparison to Fe/Co skutterudites Fe/Ni substituted ones are cheaper.
► Three out of four DDy(Fe1−xNix)4Sb12 skutterudites have a ZT > 1 at 750 K, one almost has a ZT = 1.1.
► Fe/Ni skutterudites have the same or higher efficiency than Fe/Co Sb-based skutterudites.