title: Structure of alkali borate glasses at high pressure: B and Li K-edge inelastic X-ray scattering study.
abstract: We report the first in situ boron K-edge inelastic x-ray scattering (IXS) spectra for alkali borate glasses (Li2B4O7) at high pressure up to 30 GPa where pressure-induced coordination transformation from three-coordinated to four-coordinated boron was directly probed. Coordination transformation (reversible upon decompression) begins around 5 GPa and the fraction of four-coordinated boron increases with pressure from about 50% (at 1 atm) to more than 95% (at 30 GPa) with multiple densification mechanisms, evidenced by three distinct pressure ranges for (d[4]B/dP)T. The lithium K-edge IXS spectrum for Li-borate glasses at 5 GPa shows IXS features similar to that at 1 atm, suggesting that the Li environment does not change much with pressure up to 5 GPa. These results provide improved understanding of the structure of low-z glass at high pressure.
authors.affiliation: School of Earth and Environmental Sciences, Seoul National University, Seoul, 151-742 Korea. sungklee@snu.ac.kr
authors.forename: Sung Keun
authors.initials: SK
authors.lastname: Lee
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Eng
authors.forename: Ho-kwang
authors.initials: HK
authors.lastname: Mao
authors.forename: Yue
authors.initials: Y
authors.lastname: Meng
authors.forename: Jinfu
authors.initials: J
authors.lastname: Shu