Formation of a Fine-Grained Si1–xGexThermoelectric by Spark Plasma Sintering

The kinetics of diffusion processes occurring during the formation of polycrystalline Si 1 – x Ge x nanostructures ( x = 0.20, 0.35) by spark plasma sintering in the temperature range 20–1200°C was studied for the first time. A mechanism for the formation of a SiGe solid solution is proposed as a result of a comprehensive study of the microstructure and phase composition of samples with particle sizes from 150 nm to 100 µm, together with the analysis of experimental sintering maps. It is based on the phenomenon of mutual diffusion of Si and Ge atoms that occurs during the entire sintering process. For the selected sintering modes, the grain size of the formed SiGe corresponds to the size of the initial powder particles.