Pressure-induced phase transition and electrical properties of thermoelectric Al-doped Mg{sub 2}Si

Journal Article · Wed Oct 14 00:00:00 EDT 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4933069· OSTI ID:22492814

Zhao, Jianbao; Liu, Zhenxian ^[1]; Gordon, Robert A. ^[2]; Takarabe, Kenichi ^[3]; Reid, Joel ^[4]

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1. Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015 (United States)
2. Canadian Light Source and Argonne National Laboratory, Argonne, Illinois 60439 (United States)
3. Department of Applied Science, Faculty of Science, Okayama University of Science, Okayama (Japan)
4. Canadian Light Source, Inc., Saskatoon, Saskatchewan S7N 2V3 (Canada)

A recent study has shown the thermoelectric performance of Al-doped Mg{sub 2}Si materials can be significantly enhanced at moderate pressure. To understand the cause of this phenomenon, we have performed in situ angle dispersive X-ray diffraction and infrared reflectivity measurements up to 17 GPa at room temperature. Contrary to previous experiment, using helium as a pressure transmission medium, no structural transformation was observed in pure Mg{sub 2}Si. In contrast, a phase transition from cubic anti-fluorite (Fm-3m) to orthorhombic anti-cotunnite (Pnma) was observed in the Al-doped sample at 10 GPa. Infrared reflectivity measurements show the electrical conductivity increases with pressure and is further enhanced after the phase transition. The electron density of states at the Fermi level computed form density functional calculations predict a maximum thermoelectric power factor at 1.9 GPa, which is in good agreement with the experimental observation.

• OSTI ID: 22492814
• Journal Information: Journal of Applied Physics, Vol. 118, Issue 14; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
DENSITY FUNCTIONAL METHOD
DOPED MATERIALS
ELECTRIC CONDUCTIVITY
ELECTRON DENSITY
FERMI LEVEL
MAGNESIUM SILICIDES
ORTHORHOMBIC LATTICES
PERFORMANCE
PHASE TRANSFORMATIONS
PRESSURE RANGE GIGA PA
REFLECTIVITY
TEMPERATURE RANGE 0273-0400 K
X-RAY DIFFRACTION