Synthesis of nanocrystalline bulk SiO2 stishovite with very high toughness

Nanocrystalline bulk stishovite, with pure SiO2 composition, was synthesized under high pressure and temperature. We found that this material has an extremely high fracture toughness (∼13 MPa m1/2), nearly eight times higher than that of stishovite single crystal. The measured Vickers hardness of this material was ∼29 GPa and stishovite is known to be one of the hardest oxides. This new material has potential to be used for industrial purposes because of its combination of very high hardness and toughness.