Shock wave synthesis of γ-Si3[O,N]4 in the new Freiberg blasting facility under different conditions

The new subterranean blasting facility at the TU Bergakademie Freiberg allows experiments at elevated capacities of 20 kg C4-equivalent. The new installation permits the investigation of phase transitions of γ Si3N4 under dynamic loading.
We studied the influence of plate thickness (shock duration) and different precursor-pressure powder (Cu, NaCl) mixtures at charge masses between 2000 and 20.000 g C4.
Systematic studies showed that the Mach-reflection (so called “upstreaming jetting phenomena”) is of vital importance for the synthesis success, due to the fact that the T-p ratio will increase dramatically [Milyavskii et al., 2006].
We synthesized pure γ-Si3[O,N]4 from H-bearing precursors at pressures > 25 GPa [Schlothauer et al., 2011].
The phase transition Si2N2NH into γ-Si3[O,N]4 is completely reconstructive and requires a high temperature-pressure-ratio of 176 K/GPa at pressures up to 35 GPa. Despite the high energy density during the shock wave synthesis process it will be inevitable to prepare the samples under an inert nitrogen atmosphere.