Enhanced nitridation of silicon powders using in-situ formed La2O3 nanoparticles as catalysts

Abstract

Catalytic effect of in-situ formed La2O3 nanoparticles (NPs) on the nitridation of Si powders was studied by X-ray diffraction, field emission-scanning electron microscopy and transmission electron microscope. Thermodynamic analysis and the effects of various processing parameters such as addition of catalyst and firing temperature on the nitridation of Si powders were respectively investigated. The results showed that: 1) The La2O3 NPs significantly promoted the nitridation rate of Si powders, and complete nitridation was achieved at 1623 K by using 1 wt % La2O3 NPs as catalyst; 2) Numerous Si3N4 whiskers of 20300 nm in diameter and tens of microns in length were fabricated in the final product. The Si3N4 whiskers which was believed to be governed by vapor-vaporsolid mechanism were verified to have single-crystal nature, growing along [101] direction.