Yb14ZnSb11 is isoelectronic and isostructural to the high zT thermoelectric phases, Yb14MSb11 (M = Mn, Mg), yet has been presumed to be a poor thermoelectric material because of its low electrical resistivity. First principles band structure calculations suggest that Yb14ZnSb11 has all the hallmarks of the electronic structures shown in the Mn and Mg analog thereby implicating this phase may exhibit high efficiencies as a high temperature p-type thermoelectric material. Polycrystalline Yb14ZnSb11 was synthesized through the stoichiometric reaction of Yb4Sb3, ZnSb, and YbH2 by ball milling followed by spark plasma sintering. The high purity of the resultant product was confirmed using powder x-ray diffraction and energy dispersive spectroscopy. TG/DSC experiments showed this high purity Yb14ZnSb11 to be stable over multiple temperature cycles to 1375 K. Thermoelectric properties were measured to 1275 K and show that Yb14ZnSb11 has exceptional performance at high temperatures, reaching a maximum zT of 1.2 at 1175 K if using a 2-probe Seebeck coefficient measurement, and 1.9 at 1275 K if using a 4-probe. Computational methods yield the DOS and COHP for Yb14ZnSb11, Yb14MgSb11, and Yb14MnSb11 and allow for comparison of the three phases along with a better understanding of the thermoelectric performance seen in the Zn analog.

To 1.0 and Beyond: Improving the thermoelectric performance of Yb14ZnSb11

ACS Spring 2022

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