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We report a numerical study of the field assisted sintering of silicon germanium alloys by a finite element method, which takes into account contact resistances, thermal expansion and the thermoelectric effect. The distribution of electrical and thermal fields was analyzed numerically, based on the experimental data collected from spark plasma sintering (SPS) apparatus. The thermoelectric properties of Si-Ge used within the simulation were considered as the function of density and the sintering temperature. Quantitative estimation of the temperature distribution during the sintering pointed to a significant, up to 60 °C, temperature difference within the specimen volume for the case of the sintering temperature at 1150 °C. [ABSTRACT FROM AUTHOR]

We report on thermoelectric properties of low Ge content n -type Si 0.9 Ge 0.1 –Mg 2 Si nanocomposite. Introduction of the Mg 2 Si phase into a SiGe matrix resulted in a dramatic drop of the lattice thermal conductivity beyond the previously reported lowest limit for SiGe alloys due to intensification of phonon scattering on SiGe–Mg 2 Si grain boundaries. For a sample doped with 1 at.% of Mg 2 Si, the peak value of thermoelectric figure of merit ZT reached ~ 0.8 at 800 °C. Sintered nanocomposites still exhibit high thermoelectric performance while being almost two times cheaper than Si 0.8 Ge 0.2 . [ABSTRACT FROM AUTHOR]

We report on thermoelectric properties of p -type boron doped nanostructured bulk Si 80 Ge 20 synthesized via spark plasma technique. We demonstrate that the presence of a limited amount of nanometer-sized SiO 2 inclusions, resulting from the oxidation during processing stages is an effective way to further thermal conductivity reduction in the nanostructured Si 80 Ge 20 alloys. Significant reduction of thermal conductivity and high values of Seebeck coefficient allowed us to reach a peak ZT value of about 0.72 at 800 °C in boron doped Si 80 Ge 20 . [ABSTRACT FROM AUTHOR]