Synthesis and characterization of nanostructured Mg2Si by pack cementation process

Abstract

Nowadays, energy saving is one of the most important issues to be solved worldwide. This effort is supported by the synthesis and use of thermoelectric materials. A variety of techniques have been used to prepare silicides, such as ball milling, solid state reaction, sputtering and reactive deposition epitaxy. In this work, Mg 2 Si silicide powders were synthesized by Pack Cementation, a environmental friendly, low cost and simple technique. A series of experiments were carried out at various temperatures from 500 °C to 650 °C for different deposition time and various magnesium concentrations, in order to select the optimum synthesis conditions of Mg 2 Si. The particle size and the lattice strain of Mg 2 Si was evaluated by X-ray diffraction analysis using Williamson-Hall equation, X-ray photoelectron spectroscopy illustrated the surface contaminations from the environment and Scanning Electron Microscopy revealed the morphology of the as-synthesized thermoelectric compound. Thermogravimetry measurements of Mg 2 Si powder demonstrated a significant thermal stability up to 400 ο C, as a thin magnesium oxide layer formed on the surface acts as a barrier-which is much higher than the temperature region of maximum thermoelectric efficiency. • Pack cementation process is used to form Mg 2 Si powder. • Structure and Morphology of Mg 2 Si is thoroughly examined. • Williamson-Hall method is used to estimate the crystallite size and the strain. • Thermal stability and oxidative behavior of the optimum sample is investigated. • Mg 2 Si is found to be constant to the temperature at which has maximum efficiency.