title: Observation of the transition state for pressure-induced BO₃→ BO₄ conversion in glass.
abstract: A fundamental mechanistic understanding of the pressure- and/or temperature-induced facile transformation of the coordination environment of boron is important for changing the physical properties of glass. We have used in situ high-pressure (up to 2 gigapascals) boron-11 solid-state nuclear magnetic resonance spectroscopy in combination with ab initio calculations to investigate the nature of the transition state for the pressure-induced BO3→ BO4 conversion in a borosilicate glass at ambient temperature. The results indicate an anisotropic elastic deformation of the BO3 planar triangle, under isotropic stress, into a trigonal pyramid that likely serves as a precursor for the subsequent formation of a BO4 tetrahedron.
authors.affiliation: Division of Materials Science and Engineering, University of California at Davis, Davis, CA 95616, USA.
authors.forename: Trenton
authors.initials: T
authors.lastname: Edwards
authors.affiliation: Division of Materials Science and Engineering, University of California at Davis, Davis, CA 95616, USA.
authors.forename: Takatsugu
authors.initials: T
authors.lastname: Endo
authors.affiliation: Nuclear Magnetic Resonance Facility, University of California at Davis, Davis, CA 95616, USA.
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Walton
authors.affiliation: Division of Materials Science and Engineering, University of California at Davis, Davis, CA 95616, USA. sbsen@ucdavis.edu.
authors.forename: Sabyasachi
authors.initials: S
authors.lastname: Sen