title: In situ Brillouin spectroscopy of a pressure-induced apparent second-order transition in a silicate glass.
abstract: Brillouin scattering measurements of a silicate glass, carried out at high pressures in the diamond anvil cell, show a dramatic increase in the pressure dependence of longitudinal velocity, and a discontinuity in the compressibility of the glass at about 6 GPa. While a first-order phase transition has been documented under pressure within amorphous ice, we demonstrate that an apparent second-order transition to a new, structurally distinct amorphous phase can occur via the abrupt onset of a new compressional mechanism, which may be triggered by a shift in polymerization of the glass or an onset of a change in coordination of silicon, within pressurized amorphous silicates.
authors.affiliation: School of Ocean and Earth Science and Technology University of Hawaii, Honolulu, Hawaii 96822, USA. stkachev@soest.hawaii.edu
authors.forename: S N
authors.initials: SN
authors.lastname: Tkachev
authors.forename: M H
authors.initials: MH
authors.lastname: Manghnani
authors.forename: Q
authors.initials: Q
authors.lastname: Williams