Significant enhancement of thermoelectric properties and metallization of Al-doped Mg{sub 2}Si under pressure

Journal Article · Sat Jun 07 00:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4881015· OSTI ID:22304215

Morozova, Natalia V.; Korobeinikov, Igor V.; Karkin, Alexander E.; Shchennikov, Vladimir V. ^[1]; Takarabe, Ken-ichi; Mori, Yoshihisa ^[2]; Nakamura, Shigeyuki ^[3]

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1. Institute of Metal Physics of Russian Academy of Sciences, Urals Division, 18 S. Kovalevskaya St., Yekaterinburg 620041 (Russian Federation)
2. Okayama University of Science, Ridai-cho 1-1, Kita-ku, Okayama 700-0005 (Japan)
3. Tsuyama National College of Technology, 624-1 Numa, Tsuyama 708-8509 (Japan)

We report results of investigations of electronic transport properties and lattice dynamics of Al-doped magnesium silicide (Mg{sub 2}Si) thermoelectrics at ambient and high pressures to and beyond 15 GPa. High-quality samples of Mg{sub 2}Si doped with 1 at. % of Al were prepared by spark plasma sintering technique. The samples were extensively examined at ambient pressure conditions by X-ray diffraction studies, Raman spectroscopy, electrical resistivity, magnetoresistance, Hall effect, thermoelectric power (Seebeck effect), and thermal conductivity. A Kondo-like feature in the electrical resistivity curves at low temperatures indicates a possible magnetism in the samples. The absolute values of the thermopower and electrical resistivity, and Raman spectra intensity of Mg{sub 2}Si:Al dramatically diminished upon room-temperature compression. The calculated thermoelectric power factor of Mg{sub 2}Si:Al raised with pressure to 2–3 GPa peaking in the maximum the values as high as about 8 × 10{sup −3} W/(K{sup 2}m) and then gradually decreased with further compression. Raman spectroscopy studies indicated the crossovers near ∼5–7 and ∼11–12 GPa that are likely related to phase transitions. The data gathered suggest that Mg{sub 2}Si:Al is metallized under moderate pressures between ∼5 and 12 GPa.

• OSTI ID: 22304215
• Journal Information: Journal of Applied Physics, Vol. 115, Issue 21; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM ADDITIONS
DOPED MATERIALS
ELECTRIC CONDUCTIVITY
HALL EFFECT
MAGNESIUM SILICIDES
MAGNETISM
MAGNETORESISTANCE
PHASE TRANSFORMATIONS
PLASMA
PRESSURE RANGE GIGA PA
RAMAN SPECTRA
RAMAN SPECTROSCOPY
SEEBECK EFFECT
SINTERING
TEMPERATURE RANGE 0273-0400 K
THERMAL CONDUCTIVITY
THERMOELECTRIC PROPERTIES
X-RAY DIFFRACTION