title: Structure and Properties of Silica Glass Densified in Cold Compression and Hot Compression.
abstract: Silica glass has been shown in numerous studies to possess significant capacity for permanent densification under pressure at different temperatures to form high density amorphous (HDA) silica. However, it is unknown to what extent the processes leading to irreversible densification of silica glass in cold-compression at room temperature and in hot-compression (e.g., near glass transition temperature) are common in nature. In this work, a hot-compression technique was used to quench silica glass from high temperature (1100 °C) and high pressure (up to 8 GPa) conditions, which leads to density increase of ~25% and Young's modulus increase of ~71% relative to that of pristine silica glass at ambient conditions. Our experiments and molecular dynamics (MD) simulations provide solid evidences that the intermediate-range order of the hot-compressed HDA silica is distinct from that of the counterpart cold-compressed at room temperature. This explains the much higher thermal and mechanical stability of the former than the latter upon heating and compression as revealed in our in-situ Brillouin light scattering (BLS) experiments. Our studies demonstrate the limitation of the resulting density as a structural indicator of polyamorphism, and point out the importance of temperature during compression in order to fundamentally understand HDA silica.
authors.affiliation: Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Guerette
authors.affiliation: Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Ackerson
authors.affiliation: Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
authors.forename: Jay
authors.initials: J
authors.lastname: Thomas
authors.affiliation: Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
authors.forename: Fenglin
authors.initials: F
authors.lastname: Yuan
authors.affiliation: Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
authors.forename: E
authors.initials: E
authors.lastname: Bruce Watson
authors.affiliation: Department of Earth and Environmental Sciences, Lamont-Doherty Earth Observatory at Columbia University, Palisades, NY 10964, USA.
authors.forename: David
authors.initials: D
authors.lastname: Walker
authors.affiliation: Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
authors.forename: Liping
authors.initials: L
authors.lastname: Huang