Thermoelectric properties of As-based 1111-Zintl compounds La_1-xSr_x(Zn,Cd)AsO

1111-system with the ZrCuSiAs-type structure has attracted great attention not only as the high-Tc superconductors but the high-performance thermoelectric compounds. The highest ZT in 1111-system was found in BiCuSeO with the value of ZT to be 1.4 at 923 K [1], demonstrating the high potential of the 1111-system as thermoelectric compounds. Previously, we found that LaFeAsO_1-y exhibits large power factor with values of PF = 4.1 mW/mK² at T = 75 K [2], demonstrating that As-based 1111-system can also be a candidate.
In this study, we focused on LaZnAsO and LaCdAsO (space group: P4 / nmm) compounds. Hole carriers were induced by Sr doping. Polycrystalline samples were synthesized by the solid reaction method. High dense samples were obtained by hot-press. As results, peak of the power factor of LaZnAsO was shift to high temperature comparing with LaFeAsO_1-y, achieving the value of 0.118 mW/mK2 at T=747 K. Details of sample preparation as well as thermoelectric properties will be discussed in the conference.

[1] Li-Dong Zhao, et al, Energy Environ. Sci. 7, 2900 (2014).
[2] K. Kihou, C. H. Lee, M. Miyazawa, P. M. Shirage, A. Iyo and H. Eisaki, J. Appl. Phys. 108, 033703 (2010).