Bulk-nanostructured Bi2Te3-based materials: Processing, thermoelectric properties, and challenges

This chapter presents fabrication, nanostructure characterization, and transport properties of first generation nanomaterials. The Fraunhofer Institute for Manufacturing and Applied Material Sciences IFAM‐DD, branch lab Dresden, is focused on the research and development of powder metallurgical methods for the production of multifunctional materials with enhanced properties. The nanostructuring of commercially available n‐ and p‐type Bi2Te3‐based bulk precursor materials was reached by using a top‐down route high‐energy ball milling (HEBM) combined with the spark plasma sintering (SPS) technology. The chapter discusses the results and <I>ZT</I> limiting factors, and provides an outlook to second‐generation nanomaterials. A combination of powder X‐ray diffraction (XRD), high‐accuracy energy‐dispersive X‐ray spectroscopy (EDX) in transmission electron microscopy (TEM), and energy‐filtered TEM (EFTEM) were of paramount importance for interpreting transport properties correctly. The emphasis of synthesis and analytical investigations was on control of grain size, mass density, composition, and secondary phases.