Enhancement of thermoelectric properties of Co4Sb12 Skutterudite by Al and La double filling

Abstract This work reports the enhancement of thermoelectric properties of La0.5Co4Sb12 compound due to addition of Al. A polycrystalline AlxLa0.5Co4Sb12 (0 ≤ x ≤ 0.5) skutterudites were successfully prepared by mechanical alloying and spark plasma sintering techniques. The characterization of phase structure and morphology of AlxLa0.5Co4Sb12 bulk samples are examined by XRD and SEM-EDX analysis. The results revealed that the main phase of CoSb3 skutterudite structure with a small amount of Al were distributed in the grain boundaries for the most of AlxLa0.5Co4Sb12 samples. The thermoelectric measurements of consolidated samples were evaluated from room temperature to 800 K. The electrical resistivity remarkably reduced through the addition of Al to the lowest value of 7.6 μO m at room temperature for Al0.05La0.5Co4Sb12 sample. Moreover, the absolute Seebeck coefficient was significantly improved by Al addition and the highest value of 193 μV/K was observed at 789 K for Al0.05La0.5Co4Sb12 sample. Furthermore, the same formulation showed a significant enhancement on the power factor that reached the maximum value of 4.02 × 10−3 W/mK2 at 789 K. The thermal conductivity and lattice thermal conductivity were significantly minimized to the value of 1.1 W/mK (at 789 K) and 0.64 W/mK (at 595 K), respectively for Al0.3La0.5Co4Sb12 due to the enhancement of phonon scattering. Additionally, a comprehensive improvement on the dimensionless figure of merit value ZT of 1.36 for Al0.05La0.5Co4Sb12 at 789 K has been achieved.