Growth mechanism and thermoelectric properties of β-FeSi2 matrix with Si nanowires

A novel composite material consisted of β-FeSi2 and in situ formed Si nanowires (SiNWs) with the diameter of 50–120 nm, is prepared by mechanical alloying and annealing process. The effects of ball-milling time on the formation of SiNWs are investigated systematically. The growth way of SiNWs is named as autocatalytic growth, in which no catalyst is intentionally added to the system. The possible formation mechanisms of SiNWs are discussed in detail. Due to the increase of boundary scattering, the thermal conductivity of the composite sample with SiNWs decrease significantly. Thus, the composite sample shows excellent thermoelectric performance.