Activated Reactive Consolidation Method as a New Approach to Enhanced Thermoelectric Properties of n-Type Nanostructured Mg₂Si

Abstract

The activated reactive consolidation method was implemented to enhance the thermoelectric properties of n-type Mg2Si binary components. This method consists of the preparation of a nanocomposite of highly activated starting materials using silicon nanoparticles. These particles were embedded in magnesium forming a so-called “plum-pudding microstructure”. This gives rise to a magnesium–silicon interface, which facilitates diffusion in a short time and at a lower temperature during hot consolidation. Bi–Al co-doped Mg2Si was prepared by this method and a single phase was achieved. The highest zT value of about 1.05 was achieved at 850 K with a high power factor of 3.6 × 10–3 Wm–1 K–2. The enhanced power factor is attributed to suppression of MgO and Bi2Mg3 formation and the significant increase in the electrical conductivity. Approximately 2 h of planetary ball-milling and 10 min of hot pressing at 600 °C are all of the required processes to fabricate the samples in this study. These synthesis conditions lead to the most rapid and simple process for preparing Mg2Si thermoelectric materials.