Converting n-type Co4Ge6Te6 skutterudite into p-type and enhancing its thermoelectric properties through Fe substitution

This study is devoted to converting an n-type mixed anion Co4Ge6Te6 skutterudite into a p-type material through partial substitution of Fe for Co. Co4-x Fe x Ge6Te6 (x = 0, 0.04 and 0.12) samples were prepared by solid-state methods and characterized by scanning electron microscopy and powder X-ray diffraction. Thermoelectric properties of the spark plasma sintering samples were investigated in the temperature range of 50–500 °C. The positive Seebeck and Hall coefficients of Co4-x Fe x Ge6Te6 (x = 0.04 and 0.12) suggest that the n-type Co4Ge6Te6 was successfully converted into a p-type semiconductor via the Fe substitution. Also, an increased carrier concentration in Co4-x Fe x Ge6Te6 (x = 0.04 and 0.12) leads to a significant increase in the electrical conductivity, which improves the thermoelectric performance of the mixed anion Co4-x Fe x Ge6Te6 skutterudite.