Mechanochemical synthesis and properties of thermoelectric material β-FeSi2

The mechano-chemical synthesis of thermoelectric material on the basis of beta-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 alpha, mu V/K, electrical conductivity sigma 1/Ohm * 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/sec(2) produced homogeneous powder with a superequilibrium quantity of dopant, which conversed into thermoelectric ceramics after short annealing in vacuum at low temperature (780 degrees C). The samples of ceramics with the maximum content of doping elements have increased thermoelectromotive force-up to 800 mu V/K. Mechanically alloyed ceramic is a promising material as a medium temperature thermoelectric with advanced properties for autonomous power supply units. (C) 2000 Kluwer Academic Publishers.