Preparation of micro-porous Si particles from Mg2Si powder

Polycrystalline Si powder consisting of micro-porous particles was prepared by heating Mg2Si powder at 600 °C for 40 h under a pressure of 500 Pa. The porous Si particles were composed of primary Si crystals ranging in size from 100 nm to 5 μm with pores less than 10 μm in size. Porous Si particles with similar morphology were also prepared at 700 °C for 50 Pa and 500 Pa for 10 h. The formation of the porous Si particles was attributed to Mg evaporation from Mg2Si particles, followed by crystallization of Si.

► Si powder was prepared by heating Mg2Si powder under a reduced pressure.
► The Si powder was composed of micro-porous particles.
► The porosity of the particles was estimated to be 69%.
► The particles were formed by Mg evaporation from Mg2Si particles and Si crystallization.