Thermoelectric properties of YbZn11−xAlx†

Abstract

Metallic thermoelectric materials with a high thermoelectric power factor and high thermal conductivity are favorable for transient dynamic active thermal management of microelectronics. Among these, several ytterbium intermetallic compounds demonstrate sharp peaks in their density of states due to contributions from ytterbium f-orbitals. YbZn₁₁ is one of these compounds with a Gaussian-like density of states close to its Fermi level, an advantageous shape to achieve a high thermoelectric power factor. If the Fermi-level can be adjusted, high Seebeck coefficient values are expected following the Wiedemann–Franz law. Here we present YbZn₁₁, a rarely made and studied sample, and for the first time, we report its thermoelectric and transport properties. Band structure calculations confirm the Gaussian function shape of the density of states. However, Seebeck calculations show that the Fermi level is not well positioned and ideally should be shifted by 200 meV. Al substitution for Zn (YbZn_11−xAl_x) and Zn-deficiency (YbZn_11−x) are applied to modify the band structure and to shift the Fermi level to adjust the Seebeck coefficient.