“…In the process, many metals or metal oxides additives, such as Fe, Ni, MgO, CaO, TiO 2 , Cr 2 O 3 , etc. have been reported [8,9,10,11], which act as catalyt for the nitridation of silicon powders. However, these additives cannot facilitate the growth of β-Si 3 N 4 particles with approximate spherical morphology.…”