Picosecond amorphization of SiO ₂ stishovite under tension

Abstract

Quantum simulation reveals that fast tensile amorphization is key to hard and tough ceramics made of Earth-abundant silica.

Defect-free and crystallinity-preserving ductile deformation in semiconducting Ag2S

“…First, simple shear deformations with γ = 0.05 are loaded every 1.0 ps, which corresponds to the shear rate dγ / dt = 5.0 × 10 10 s −1 . While this value seems quite large compared with experimental conditions, we note that our previous tensile simulation with the same order of strain rate provides reasonable structural behaviors 38 . The FPMD simulations with the (100)[010], (100)[001], (010)[100], (010)[001], (001)[100], and (001)[010] shear systems of Ag 2 S and Ag 2 Se up to γ = 0.50 (= 10 ps) were performed to study the structural behaviors under shear strains, where the ( KLM )[ klm ] shear system means that the ( KLM ) plane is slipped toward [ klm ] direction during the shear deformation (Supplementary Fig.…”

Application of First-Principles-Based Artificial Neural Network Potentials to Multiscale-Shock Dynamics Simulations on Solid Materials

“…For example, it is reported that silica (SiO2) transforms into nanopolycrystalline form of stishovite, which is a high-pressure polymorph of silica, during highpressure shock compression 1 . This nano-polycrystalline stishovite is nominated for nextgeneration high performance ceramics since its high hardness and toughness [6][7][8][9] . To study the atomistic scale dynamics in materials under such extreme conditions, molecular dynamics (MD) simulations exert great power because those are able to chase the atomic trajectories with extremely high time resolution of femto-second.…”

“…Investigating wave propagation properties and shock-wave-induced structural dynamics in earth-abundant materials is important not only for geodynamics research but also to understand material processes. − For example, it is reported that silica (SiO 2 ) transforms into the nanopolycrystalline form of stishovite, which is a high-pressure polymorph of silica, during high-pressure shock compression . This nanopolycrystalline stishovite has been nominated for next-generation high-performance ceramics because of its high hardness and toughness. − To study the atomistic-scale dynamics in materials under such extreme conditions, molecular dynamics (MD) simulations exert great power because they are able to chase the atomic trajectories with extremely high time resolution (femtoseconds). In particular, the first-principles MD (FPMD) method based on density functional theory (DFT) calculations provides us great insight into microscopic mechanisms of such complex phenomena from the viewpoint of electronic states.…”

Plasmon-Induced Ultrafast Hydrogen Production in Liquid Water

“…Therefore, plasmon-induced water splitting to produce H 2 could be much more efficient than heat-induced reactions. Besides, OH radicals easily spread away from the Au 20 cluster and recombine to form H 2 O 2 or H 2 + O 2 on the supporting substrate (e.g., inert oxides or p-semiconductors), excluding the possibility of catalyst poisoning by reaction products . Instead, an inert Al 2 O 3 layer is formed in the case of water splitting on Al clusters.…”