Enhancement in Thermoelectric Performance in Ti-doped Yb_0.4Co₄Sb₁₂ Skutterudites via Carrier Optimization and Phonon...

Yb_0.4Co₄Sb₁₂, 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_zCo_4-xTi_xSb₁₂ (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·K²) at 675 K in Yb_0.4Co_3.96Ti_0.04Sb₁₂. Adversely, a significant reduction in thermal conductivity is obtained from ∼7.69 W/(m·K) (Co₄Sb₁₂) to ∼3.50 W/(m·K) (Yb_0.4Co_3.96Ti_0.04Sb₁₂) 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_0.4Co_3.96Ti_0.04Sb₁₂, which demonstrates it to be an efficient material suitable for intermediate temperature thermoelectric applications.