Solid-state synthesis of Mg2Si via short-duration ball-milling and low-temperature annealing

In this work, a short duration ball-milling of elemental Mg and Si followed by a thermal treatment is suggested in order to synthesize magnesium silicide via solid-state reaction. The formation of magnesium silicide was studied in terms of its structure and thermal characteristics by powder X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and differential scanning calorimetry. Pure Mg2Si was formed after short milling and heating at temperatures as low as 280 °C. Differential scanning calorimetry analysis was performed to study the kinetics of the reaction. The activation energy of the reaction was calculated using the Ozawa–Flynn–Wall and Friedman methods. The thermoelectric properties suggested semiconducting behavior whereas thermal conductivity values of highly dense hot-pressed pellets are consistent with the literature.

Thermographs of ball-milled Mg and Si powders (1 and 2) show exothermic areas suggesting Mg2Si formation at low temperatures. Unmilled Mg and Si mixture (3) forms Mg2Si at higher temperatures. Figure optionsDownload as PowerPoint slideHighlights
► Ball-milling process is crucial for the formation of pure Mg2Si at low temperatures.
► Synthesis profiles based on different temperature settings and duration are suggested.
► Thermal analysis confirms the shift of the Mg2Si formation at low temperatures.