skip to main content

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

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.
Authors:
; ; ;  [1] ;  [2] ;  [3] ; ;  [4] ;  [5]
  1. Institute of Metal Physics of Russian Academy of Sciences, Urals Division, 18 S. Kovalevskaya St., Yekaterinburg 620041 (Russian Federation)
  2. Bayerisches Geoinstitut, Universität Bayreuth, Universitätsstrasse 30, D-95447 Bayreuth (Germany)
  3. (Russian Federation)
  4. Okayama University of Science, Ridai-cho 1-1, Kita-ku, Okayama 700-0005 (Japan)
  5. Tsuyama National College of Technology, 624-1 Numa, Tsuyama 708-8509 (Japan)
Publication Date:
OSTI Identifier:
22304215
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 21; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
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