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The nanocrystalline high pressure phases of Si and diamond were synthesized by thermal spray. In this technique, the particles melt and accelerate to impact and form a deposit. The shock wave generated by the impact of the droplets propagates through
the underlying layer, which experiences a phase transition to a high pressure form.
 a) A bright -field TEM of VPS deposits on (100) Si showing fine dispersion of metastable nanocrystalline phases in Si-I matrix. b) The corresponding diffraction pattern.
  A bright- field micrograph showing the fine dispersion of hexagonal diamond (Si-IV) of VPS deposits on (100) Si.
 A TEM image showing fine dispersion of diamond particles in graphite matrix. The corresponding dp shows diamond and graphite reflections.
The shock pressure is obtained by Rankine-Hugoniot equation P = d v u, where d is the density, v is the shock velocity and u is the velocity of the compressed material. |
