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 μΩm 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.
[Display omitted]
•AlxLa0.5Co4Sb12 skutterudite samples were prepared using mechanical alloying and spark plasma sintering.•Al addition serve to decrease the electrical resistivity of La0.5Co4Sb12 skutterudites.•A low thermal conductivity of Al0.05La0.5Co4Sb12 was achieved.•Concurrent improvement of electrical conductivity and Seebeck coefficient was achieved.•Significantly increased power factor of 4.02 × 10−3 W/mk2 at 789 K.