Enhanced thermoelectric properties of Zintl phase CaZn₂Sb₂ by chemical substitution of Eu.
Tessera Alemneh1,2,3*, Pai-Chun Wei12, Szu-yuan Chen1,3, Yang-Yuan Chen2
1Physics, National Central University, Jhongli, Taiwan
2Institute of Physics, Academia Sinica, Taipei, Taiwan
3Molecular Science and Technology, Taiwan International Graduate Program, Institute of Atomic and Molecular Sciences, Taipei, Taiwan
* presenting author:Tessera Alemneh Wubieneh, email:alemneh.tessera@gmail.com
It has been shown that the thermoelectric properties of the Zintl phase compound AZn₂Sb₂ (A is alkali metal, alkaline earths or lanthanide element) can be finely tuned via A-site substitution in the cation framework. In this report, we investigate the thermoelectric properties of Eu-substituted Ca1-xEuxZn₂Sb₂ (with x = 0.1, 0.3, 0.7, 0.9 and 1) compounds, including their electrical resistivity, Seebeck coefficient and thermal conductivity in the temperature range of 300 K to 750 K. The Ca1-xEuxZn₂Sb₂ bulk samples have been synthesized via a direct solid state reaction of the elements followed by appropriate annealing, grinding and spark plasma sintering for densification. It is found that the Eu substitution effectively lowers the thermal conductivity for all samples at high temperature, while it significantly increase the Seebeck coefficient. As a result, the dimensionless figure of merit, ZT value of 0.7 has been attained at 750 K for sample with x = 0.9.

Keywords: thermoelectric