Synthesis of nanocrystalline silicon using the recrystallisation of binary silica cryogel/Mg system via self‐propagating high‐temperature combustion in the presence of NaCl as a metal halide diluent

Abstract

Self-propagating high-temperature synthesis as a low energy consumption and simple approach was employed to synthesise silicon nanocrystal from the monolithic silica cryogel prepared by freeze drying. The recrystallisation process of silicon was investigated under combustion at 800, 900 and 1000°C and the uniform coral-like structure was achieved at 1000°C. The results of Raman and X-ray diffraction analysis showed the decrease in ignition time to 40 s for 1000°C temperature, leading to the decrement of crystalline size to 10.85 A°and the raise of average lattice strain to 0.152% due to accelerating recrystallisation. In addition, NaCl diluent consumed the excess heat generated during exothermic reaction and decreased the crystalline size to 10.79 A°thanks to its 0.8 W/m K thermal conductivity.