Effects of Mechanical Alloying and Grinding on the Preparation and Thermoelectric Properties of β-FeSi<SUB>2</SUB> (<I>Overview</I>)

Abstract

Improving effects of mechanical alloying (MA) and grinding (MG) on the preparation processes as well as on the thermoelectric properties of semiconducting β-FeSi 2 were reviewed. MA and MG strongly accelerates the preparation reaction to form β-phase from elemental powders and from the mixture of α-Fe 2 Si 5 and e-FeSi. The electrical resistivity significantly decreased due to the dispersion of fine particles of metallic phase, e.g. e-FeSi phase. As a result, the power factor Q 2 /ρ was significantly improved. Figure of merit Z = Q 2 /ρκ was also improved by MA and MG due to the decrease in the thermal conductivity K. This is due to a decrease in grain size of the β-phase which causes an increase in phonon scattering at the grain boundaries. MA and MG are promissing techniques for the acceleration of β-FeSi 2 formation as well as the improvement of the thermoelectric properties of β-FeSi 2 .