Thermoelectric Properties of (Ba,K)Zn2As2 Crystallized in the ThCr2Si2-type Structure

Haruno Kunioka; Kunihiro Kihou; Daichi Kato; Hidetomo Usui; Tsutomu Iida; Hirotaka Nishiate; Kazuhiko Kuroki; Atsushi Yamamoto; Chul-Ho Lee

doi:10.1021/acs.inorgchem.9b02680

Thermoelectric Properties of (Ba,K)Zn₂As₂ Crystallized in the ThCr₂Si₂-type Structure

Inorg Chem. 2020 May 4;59(9):5828-5834. doi: 10.1021/acs.inorgchem.9b02680. Epub 2020 Apr 10.

Authors

Haruno Kunioka^{1

2}, Kunihiro Kihou¹, Daichi Kato³, Hidetomo Usui⁴, Tsutomu Iida², Hirotaka Nishiate¹, Kazuhiko Kuroki³, Atsushi Yamamoto¹, Chul-Ho Lee^{1

2}

Affiliations

¹ National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan.
² Department of Materials Science and Technology, Tokyo University of Science, Katsushika, Tokyo 125-8585, Japan.
³ Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan.
⁴ Department of Physics and Materials Science, Shimane University, Matsue, Shimane 690-8504, Japan.

PMID: 32275396
DOI: 10.1021/acs.inorgchem.9b02680

Abstract

The compound Ba_1-xK_xZn₂As₂ has a low-temperature phase (α-phase) crystallized in the α-BaCu₂S₂-type structure and a high-temperature phase (β-phase) crystallized in the ThCr₂Si₂-type structure. We successfully obtained the β-phase at room temperature as a metastable state by quenching from above the structural phase transition. This allowed us to determine the thermoelectric properties of the β-phase from room to high temperature in the range of 0.00 ≤ x ≤ 0.10. The lattice thermal conductivity is quite low, with a value less than 1 W/mK at 773 K, independent of x. The effective suppression may be due to lattice instability in the underdoped region and to randomness in the overdoped region. The maximum dimensionless figure-of-merit ZT was 0.30 at 773 K for x = 0.03 with the power factor of 0.61 mW/mK², which is relatively high for a ThCr₂Si₂-type structure. The results demonstrate the effectiveness of quenching for obtaining a low lattice thermal conductivity, thus providing a new method for attaining high thermoelectric performance.