title: High-pressure x-ray diffraction studies on the structure of liquid silicate using a Paris-Edinburgh type large volume press.
abstract: An experimental setup for high-pressure liquid structure studies with synchrotron x-ray diffraction using the Paris-Edinburgh press has been installed at station 16-BM-B (HPCAT) of the Advanced Photon Source, Argonne National Laboratory. By collecting energy-dispersive data with a synchrotron white beam at various 2θ angles, the present device allows us to obtain the structure factor, S(Q), over a wide range of Q ( = 4πsinθ∕λ) owing to the excellent angular accessibility up to 37° in 2θ and high energy photons well beyond 100 keV. We have successfully collected XRD data on silicate (albite, NaAlSi(3)O(8)) liquids with Q up to ∼22 Å(-1) and pressure up to 5.3 GPa and temperature 1873 K, and obtained the radial distribution function, G(r), with a reasonable resolution. The T-O bond length (where T = Al, Si), which is a fundamental measure of local structure for aluminous silicate consisting of SiO(n) and AlO(n) polyhedra (tetrahedra at 1 atm condition), was found to be slightly shortened to 1.626 Å compared to that of glass at 1 atm. The T-O-T bound angle, which is the linkage of the above polyhedra, is the most responsible for densification. The T-O-T peak in G(r) splits into two peaks, suggesting a differentiation of the bond angle at high-pressure. The present technical development demonstrates that the Paris-Edinburgh press is suitable for studies of silicate liquids under high-pressure conditions.
authors.affiliation: Geodynamics Research Center, Ehime University, Matsuyama, Japan. a-yamada@sci.ehime-u.ac.jp
authors.forename: Akihiro
authors.initials: A
authors.lastname: Yamada
authors.forename: Yanbin
authors.initials: Y
authors.lastname: Wang
authors.forename: Toru
authors.initials: T
authors.lastname: Inoue
authors.forename: Wenge
authors.initials: W
authors.lastname: Yang
authors.forename: Changyong
authors.initials: C
authors.lastname: Park
authors.forename: Tony
authors.initials: T
authors.lastname: Yu
authors.forename: Guoyin
authors.initials: G
authors.lastname: Shen