Cubic Si6−zAlzOzN8−z (z=1.8 and 2.8) spinels formed by shock compression

We present the formation of cubic Si6−zAlzOzN8−z (z=1.8 and 2.8) spinels by shock compressions from the corresponding β-sialon. Formed sialon spinels coexist with considerable amounts of the amorphous phase. The amorphization is considered to be a solid–solid reaction due to the sluggish phase transition under shock compression. The lattice parameter of the spinel increases and the density decreases with increasing z parameter. Shock-synthesized sialon spinels are nanocrystals with most grain sizes less than 30 nm and consist of main units of SiN4, SiN6 and AlO6.