Magnetic, transport, and structural properties of Fe[sub 1[minus][ital x]]Ir[sub [ital x]]Si

Journal Article · Thu Sep 15 00:00:00 EDT 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.50.8207· OSTI ID:6959625

Sales, B C; Jones, E C; Chakoumakos, B C; Fernandez-Baca, J A; Harmon, H E; Sharp, J W ^[1]; Volckmann, E H ^[2]

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1. Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6056 (United States)
2. Marlow Industries, Dallas, Texas 75238 (United States)

Magnetic susceptibility, resistivity, Seebeck, Hall, and powder x-ray and neutron-diffraction measurements were used to characterize single crystals of FeSi and polycrystalline samples of Fe[sub 1[minus][ital x]]Ir[sub [ital x]]Si for [ital x][lt]0.2. The Rietveld refinement of low-temperature powder neutron-diffraction data on FeSi showed no change in the space group and no structural anomalies from 4 to 300 K. Magnetic and transport data from 4 to 700 K are consistent with the characterization of FeSi as a narrow-gap semiconductor ([ital E][sub [ital g]]=1200 K) with strong intrasite correlations for the states just below and above the gap. Fits to the magnetic susceptibility and resistivity data suggest that the magnetic (or direct) gap may be larger than the transport (indirect) gap. Electron mobilities in FeSi are very low (3--5 cm[sup 2]/V s). The thermopower of FeSi has a large positive peak (500 [mu]V/K) at 50 K that is attributed to an unusually strong phonon-drag mechanism. Iridium acts as an electron donor in the Fe[sub 1[minus][ital x]]Ir[sub [ital x]]Si alloys. As the iridium doping level is increased, there is a rapid decrease in the low-temperature resistivity and a large negative ([minus]140 [mu]V/K) phonon-drag contribution to the thermopower. For Peltier cooling applications, a maximum value for [ital ZT] of 0.07 was found for a Fe[sub 0.95]Ir[sub 0.05]Si alloy at 100 K.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6959625
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 50:12; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
IRIDIUM SILICIDES
ELECTRIC CONDUCTIVITY
MAGNETIC SUSCEPTIBILITY
IRON SILICIDES
ELECTRON MOBILITY
HALL EFFECT
MONOCRYSTALS
NEUTRON SPECTROSCOPY
POLYCRYSTALS
SEEBECK EFFECT
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0000-0013 K
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
TERNARY ALLOY SYSTEMS
X-RAY SPECTROSCOPY
ALLOY SYSTEMS
CRYSTALS
ELECTRICAL PROPERTIES
IRIDIUM COMPOUNDS
IRON COMPOUNDS
MAGNETIC PROPERTIES
MOBILITY
PARTICLE MOBILITY
PHYSICAL PROPERTIES
REFRACTORY METAL COMPOUNDS
SILICIDES
SILICON COMPOUNDS
SPECTROSCOPY
TEMPERATURE RANGE
TRANSITION ELEMENT COMPOUNDS
360606* - Other Materials- Physical Properties- (1992-)