Preparation and thermoelectric properties of Ga-substituted p-type fully filled skutterudites CeFe4−xGaxSb12

We demonstrate a successful substitution of Ga at the Fe sites with a solubility limit of −0.11 in the p-type filled skutterudite compounds CeFe4−xGaxSb12. With increasing Ga content, the electrical conductivity declines while the Seebeck coefficient improves gradually, consistent with the expected decrease in hole concentration due to the extra electrons introduced by Ga. Moreover, the resemblances in electrical transport properties between Ga- and Co-substituted systems with similar composition indicate that Ga doping exerts little influence on the electronic structure near the top of the valence band. The phonon transport is scarcely affected by the introduction of Ga because of negligible differences in atomic masses and sizes of Ga and Fe. The thermoelectric performance of Ga-substituted samples is slightly improved in the temperature range of 600 K to 800 K with respect to that of Ga-free sample, revealing a favorable effect of Ga-substitution on the intermediate temperature power generation application of this promising p-type material.