Higher thermoelectric performance of Zintl phases (Eu0.5Yb0.5)1-xCaxMg2Bi2 by band engineering and strain fluctuation

Jing Shuai, Huiyuan Geng, Yucheng Lan, Zhuan Zhu, Chao Wang, Zihang Liu, Jiming Bao, Ching Wu Chu, Jiehe Sui, Zhifeng Ren

Research output: Contribution to journalArticlepeer-review

90 Citations (Scopus)

Abstract

Complex Zintl phases, especially antimony (Sb)-based YbZn0.4Cd1 6Sb2 with figure-of-merit (ZT) of ∼1.2 at 700 K, are good candidates as thermoelectric materials because of their intrinsic "electron-crystal, phonon-glass" nature. Here, we report the rarely studied p-type bismuth (Bi)-based Zintl phases (Ca,Yb,Eu)Mg2Bi2 with a record thermoelectric performance. Phase-pure EuMg2Bi2 is successfully prepared with suppressed bipolar effect to reach ZT ∼ 1. Further partial substitution of Eu by Ca and Yb enhanced ZT to ∼1.3 for Eu0.2Yb0.2Ca0.6Mg2Bi2 at 873 K. Density-functional theory (DFT) simulation indicates the alloying has no effect on the valence band, but does affect the conduction band. Such band engineering results in good p-type thermoelectric properties with high carrier mobility. Using transmission electron microscopy, various types of strains are observed and are believed to be due to atomic mass and size fluctuations. Point defects, strain, dislocations, and nanostructures jointly contribute to phonon scattering, confirmed by the semiclassical theoretical calculations based on a modified Debye-Callaway model of lattice thermal conductivity. This work indicates Bi-based (Ca, Yb,Eu)Mg2Bi2 is better than the Sb-based Zintl phases.

Original languageEnglish
Pages (from-to)E4125-E4132
JournalProceedings of the National Academy of Sciences of the United States of America
Volume113
Issue number29
DOIs
Publication statusPublished - 2016 Jul 19

All Science Journal Classification (ASJC) codes

  • General

Fingerprint

Dive into the research topics of 'Higher thermoelectric performance of Zintl phases (Eu<sub>0.5</sub>Yb<sub>0.5</sub>)<sub>1-x</sub>Ca<sub>x</sub>Mg<sub>2</sub>Bi<sub>2</sub> by band engineering and strain fluctuation'. Together they form a unique fingerprint.

Cite this