期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 115, 期 21, 页码 5332-5337出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1802020115
关键词
thermoelectric; phase transition; germanium telluride; Mn alloying; band-structure engineering
资金
- US Department of Energy [DE-SC0010831]
- US Air Force Office of Scientific Research [FA9550-15-1-0236]
- T. L. L. Temple Foundation
- John J. and Rebecca Moores Endowment
- State of Texas through the Texas Center for Superconductivity at the University of Houston
- National Natural Science Foundation of China [51622101]
Germanium telluride (GeTe)-based materials, which display intriguing functionalities, have been intensively studied from both fundamental and technological perspectives. As a thermoelectric material, though, the phase transition in GeTe from a rhombohedral structure to a cubic structure at similar to 700 K is a major obstacle impeding applications for energy harvesting. In this work, we discovered that the phase-transition temperature can be suppressed to below 300 K by a simple Bi and Mn codoping, resulting in the high performance of cubic GeTe from 300 to 773 K. Bi doping on the Ge site was found to reduce the hole concentration and thus to enhance the thermoelectric properties. Mn alloying on the Ge site simultaneously increased the hole effective mass and the Seebeck coefficient through modification of the valence bands. With the Bi and Mn codoping, the lattice thermal conductivity was also largely reduced due to the strong point-defect scattering for phonons, resulting in a peak thermoelectric figure of merit (ZT) of similar to 1.5 at 773 K and an average ZT of similar to 1.1 from 300 to 773 K in cubic Ge0.81Mn0.15Bi0.04Te. Our results open the door for further studies of this exciting material for thermoelectric and other applications.
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