Fast synthesis of nanocrystalline Mg2Si by microwave heating: a new route to nano-structured thermoelectric materials

Abstract

The ultra fast synthesis of nanocrystalline Mg(2)Si was carried out using microwave radiation. The elemental precursors were first milled together under dry conditions to get fine particles. The resulting mixture of powders of Mg and Si was cold pressed before being heated by microwave irradiation. Precursors and products were analyzed by X-ray diffraction and scanning electron microscopy. The high energy ball milling parameters utilized to prepare the reactive powders have quite an influence on the behavior of the mixture under irradiation. Moreover, SEM imaging demonstrates that the power and time of irradiation are crucial for the grain growth of the Mg(2)Si and must be adequately controlled in order to avoid the decomposition of the phase. Our results show that we successfully managed to easily and quickly synthesize homogeneous nanocrystalline Mg(2)Si with particle size smaller than 100 nm using a microwave power of only 175 W for two minutes on powders ball milled for two hours.

Monolithic porous magnesium silicide

“…A long reaction time may also risk the decomposition of Mg 2 Si into Mg and Si. 30,31 Influence of the reaction temperature…”

Nano Bulk Thermoelectrics: Concepts, Techniques, and Modeling

“…Numerous experimental techniques such as mechanical alloying, hot-pressing, and spark plasma sintering have been reported for the preparation and synthesis of Mg 2 Si-based thermoelectric materials [121][122][123][124][125]. Recent reports also demonstrate novel methods such as microwave processing to fabricate nano bulk structures of Si x Ge 1Àx and Mg 2 Si [126,127].…”

Silicide Nanopowders as Low-Cost and High-Performance Thermoelectric Materials

“…Their results show that the method can readily synthesize homogeneous nanocrystalline Mg 2 Si with particle size smaller than 100 nm, with a microwave power of 100 to 200 W for only a few minutes (on powders ball milled for 2 h). 37 Maximum ZT values of 0.7 and 0.35 at 770 K were obtained for n-and p-type Mg 2 Si-based materials (Fig. 5).…”

“…[37][38][39] In this route, nanocrystalline Mg 2 Si powders were synthesized at a high yield by employing microwave radiation. The elemental precursors (Si and Mg) were first milled together under dry conditions to get fine particles.…”