Unlocking the thermoelectric potential of the Ca(14)AlSb(11) structure type

Yb(14)MnSb(11) and Yb(14)MgSb(11) are among the best p-type high-temperature (>1200 K) thermoelectric materials, yet other compounds of this Ca(14)AlSb(11) structure type have not matched their stability and efficiency. First-principles computations show that the features in the electronic structures that have been identified to lead to high thermoelectric performances are present in Yb(14)ZnSb(11), which has been presumed to be a poor thermoelectric material. We show that the previously reported low power factor of Yb(14)ZnSb(11) is not intrinsic and is due to the presence of a Yb(9)Zn(4+x)Sb(9) impurity uniquely present in the Zn system. Phase-pure Yb(14)ZnSb(11) synthesized through a route avoiding the impurity formation reveals its exceptional high-temperature thermoelectric properties, reaching a peak zT of 1.2 at 1175 K. Beyond Yb(14)ZnSb(11), the favorable band structure features for thermoelectric performance are universal among the Ca(14)AlSb(11) structure type, opening the possibility for high-performance thermoelectric materials.