[SY-O7] Symposium O-7

[SY-O7] Shear-induced amorphization of silicon and diamond yields liquid-like amorphous solids

^○Gianpietro Moras¹, Andreas Klemenz¹, Thomas Reichenbach¹, Adrien Gola², Hiroshi Uetsuka³, Michael Moseler^1,4, Lars Pastewka^1,5 (1.Fraunhofer Institute for Mechanics of Materials IWM, Germany, 2.Institute for Applied Materials, Karlsruhe Institute of Technology, Germany, 3.Asahi Diamond Industrial Co. Ltd., Japan, 4.Institute of Physics, University of Freiburg, Japan, 5.Department of Microsystems Engineering, University of Freiburg, Germany)

Silicon and diamond are brittle materials with the same crystal structure but opposite density change upon melting. Using molecular dynamics simulations, we show that both crystals can respond to shear deformation by undergoing mechanical amorphization. The resulting amorphous material has liquid-like structure, is denser than the crystal in silicon and less dense than the crystal in diamond. As a result, as normal pressure increases, amorphization, which is often related to nanoscale wear, is enhanced in silicon but suppressed in diamond. Moreover, shear-induced amorphization of silicon yields a high-density, ductile amorphous material at pressures much lower than the polyamorphic transition (~14 GPa) observed upon hydrostatic compression. These results are potentially relevant for the friction properties of other crystals that densify upon melting and show polyamorphism, like germanium and ice.