Effects of structural differences in starting materials on the formation behavior of cubic silicon nitride by shock compression

Abstract

Cubic silicon nitride (c-Si₃N₄) was prepared at 37–38 GPa and ~1773 K by shock compression of residues of polysilazane, perhydropolysilazane (PHPS), pyrolyzed at 873, 1073 and 1273 K for 2 h. The residues pyrolyzed at 873 and 1073 K were amorphous materials, while the residue pyrolyzed at 1273 K consisted mainly of crystalline α-Si₃N₄. The relative amount of c-Si₃N₄ was the smallest in the shock-compressed product of the residue pyrolyzed at 1273 K, indicating that use of amorphous residues is advantageous for formation of c-Si₃N₄.