T. Tokiai et al., THERMOELECTRIC PROPERTIES OF MN-DOPED IRON DISILICIDE CERAMICS FABRICATED FROM RADIOFREQUENCY PLASMA-TREATED FINE POWDERS, Journal of Materials Science, 32(11), 1997, pp. 3007-3011
Fine particles of Fe0.92Mn0.08Si2.00, 200 nm in size, were produced us
ing a high-frequency plasma. The powders were sintered at temperatures
between 1323 and 1423 K in vacuum and then heat treated at 1073 K to
transform them into thermoelectric semiconducting iron disilicide. The
relative density of the samples was as low as 70-77%, and the microst
ructure was composed of several tens of micrometre grains and continuo
us pores. The sample sintered at 1423 K, in particular, showed a figur
e of merit, Z, of 2.0 x 10(-4) K-1 at 870 K which was 20% larger than
those previously reported. The increase in Z was found to be attributa
ble to the increase in Seebeck coefficient and the decrease in thermal
conductivity.