Hypothetical efficient thermoelectrics based on nanoparticles in alloys of silicide nanocomposites were predicted by Mingo et al. This investigation presents the experimental realization of an n-type silicon germanium alloy with an embedded metallic α-phase iron silicide (FeSi _(2) ). The dimensionless thermoelectric figure of merit ( ZT ) of the nanocomposite material was higher than the peak ZT of the conventional single phase Si _(0.80) Ge _(0.20) over a broad temperature range (650–1000 °C) while consuming smaller amounts of germanium. The addition of 2.5% silver to the nanocomposite, which acted as a sintering aid, reduced the sintering temperature and resulted in smaller thermal conductivity. The optimum material composition of (Si _(0.88) Ge _(0.12) ) _(0.925) –(FeSi _(2) ) _(0.05) –Ag _(0.025) was found after investigation of a large number of nanocomposite materials. The combination of X-ray diffraction, energy-dispersive X-ray spectroscopy, and transmission electron microscopy analysis confirmed a uniform distribution of α-FeSi _(2) nanoparticles in the microstructure.
展开▼
