Enhancement in Thermoelectric Performance in Ti-doped Yb<sub>0.4</sub>Co<sub>4</sub>Sb<sub>12</sub> Skutterudites via Carrier Optimization and Phonon Anharmonicity
Akshara Dadhich, Madhuvathani Saminathan, Saravanan Muthiah, Animesh Bhui, Suresh Perumal, M. S. Ramachandra Rao, K. Sethupathi
Abstract
Yb 0.4 Co 4 Sb 12, being a well-studied system, has shown notably high thermoelectric performance due to the Yb filler atom-driven large concentration of charge carriers and lower value of thermal conductivity. In this work, the thermoelectric performance of Yb z Co 4– x Ti x Sb 12 (where z = 0, x = 0 and z = 0.4, x = 0, 0.04, and 0.08) upon Ti doping prepared by the melt-quenched-annealing followed by spark plasma sintering (SPS) has been studied in the temperature range of 300–700 K. Addition of Yb and doping of donor Ti at the Co site simultaneously increase the electrical conductivity to 1453.5 S/cm at 300 K, which ultimately boosts the power factor as high as ∼4.3 mW/(m·K 2 ) at 675 K in Yb 0.4 Co 3.96 Ti 0.04 Sb 12 . Adversely, a significant reduction in thermal conductivity is obtained from ∼7.69 W/(m·K) (Co 4 Sb 12 ) to ∼3.50 W/(m·K) (Yb 0.4 Co 3.96 Ti 0.04 Sb 12 ) at ∼300 K. As a result, the maximum zT is achieved as ∼0.85 at 623 K with high hardness of 584 H V for the composition of Yb 0.4 Co 3.96 Ti 0.04 Sb 12, which demonstrates it to be an efficient material suitable for intermediate temperature thermoelectric applications.