Mechanochemical synthesis and properties of thermoelectric material β-FeSi2

Abstract

The mechano-chemical synthesis of thermoelectric material on the basis of β-FeSi₂ has been investigated. The mixture of FeSi and amorphous Si has been shown to be a optimum precursor to produce the thermoelectric ceramics. The ceramics properties (thermoelectric power α, μV/K, electrical conductivity σ 1/Ω*cm) have been considerably improved by means of doping with superequilibrium quantity of 12% of aluminium (substitution of silicon) or 10% of cobalt (substitution of iron). The mechanical alloying in a high energy ball mill, under the acceleration of treating balls 800 m/sec² produced homogeneous powder with a superequilibrium quantity of dopant, which conversed into thermoelectric ceramics after short annealing in vacuum at low temperature (780°C). The samples of ceramics with the maximum content of doping elements have increased thermoelectromotive force-up to 800 μV/K. Mechanically alloyed ceramic is a promising material as a medium temperature thermoelectric with advanced properties for autonomous power supply units.