Hydrogen sites in the dense hydrous magnesian silicate phase E: a pulsed neutron powder diffraction study

Naotaka Tomioka, Takuo Okuchi, Narangoo Purevjav, Jun Abe, Stefanus Harjo

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Hydrogen site positions and occupancy in the crystal structure of dense hydrous magnesium silicate (DHMS) phase E were determined for the first time by pulsed neutron powder diffraction. A fully deuterated pure phase E powder sample, which had space group (Formula presented.) and lattice parameters of a = 2.97065(8) Å and c = 13.9033(4) Å, was synthesized at 15 GPa and 1100 °C. Through quantitative evaluation of refined structure parameters obtained with sufficient spatial resolution and very high signal-to-background ratio, we conclude that the O–D dipoles in the refined phase E structure are tilted by 24° from the direction normal to the layers of edge-shared MgO6 octahedra (octahedral layers). The tilted dipole structure of phase E is in remarkable contrast to that of brucite, Mg(OH)2, which has dipoles exactly normal to the octahedral layer. This contrast exists because the O–Si–O bonding unique in the phase E structure connects two adjacent octahedral layers and thereby reduces the interlayer O···O distance. This shrinkage of the interlayer distance induces the tilting of the O–D dipole and also generates unique O–D···O hydrogen bonding connecting all the layers in the phase E structure.

Original languageEnglish
Pages (from-to)1-9
Number of pages9
JournalPhysics and Chemistry of Minerals
DOIs
Publication statusAccepted/In press - Dec 24 2015

Fingerprint

Magnesium Hydroxide
neutron diffraction
Silicates
Neutron powder diffraction
Powders
Lattice constants
Magnesium
Hydrogen
Hydrogen bonds
silicate
Crystal structure
hydrogen
brucite
crystal structure
magnesium
spatial resolution
Direction compound
Florisil

Keywords

  • DHMS phase
  • High pressure
  • Hydrogen sites
  • Neutron diffraction
  • Phase E

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Materials Science(all)

Cite this

Hydrogen sites in the dense hydrous magnesian silicate phase E : a pulsed neutron powder diffraction study. / Tomioka, Naotaka; Okuchi, Takuo; Purevjav, Narangoo; Abe, Jun; Harjo, Stefanus.

In: Physics and Chemistry of Minerals, 24.12.2015, p. 1-9.

Research output: Contribution to journalArticle

@article{41554ea39ac9467db88e4694a2634380,
title = "Hydrogen sites in the dense hydrous magnesian silicate phase E: a pulsed neutron powder diffraction study",
abstract = "Hydrogen site positions and occupancy in the crystal structure of dense hydrous magnesium silicate (DHMS) phase E were determined for the first time by pulsed neutron powder diffraction. A fully deuterated pure phase E powder sample, which had space group (Formula presented.) and lattice parameters of a = 2.97065(8) {\AA} and c = 13.9033(4) {\AA}, was synthesized at 15 GPa and 1100 °C. Through quantitative evaluation of refined structure parameters obtained with sufficient spatial resolution and very high signal-to-background ratio, we conclude that the O–D dipoles in the refined phase E structure are tilted by 24° from the direction normal to the layers of edge-shared MgO6 octahedra (octahedral layers). The tilted dipole structure of phase E is in remarkable contrast to that of brucite, Mg(OH)2, which has dipoles exactly normal to the octahedral layer. This contrast exists because the O–Si–O bonding unique in the phase E structure connects two adjacent octahedral layers and thereby reduces the interlayer O···O distance. This shrinkage of the interlayer distance induces the tilting of the O–D dipole and also generates unique O–D···O hydrogen bonding connecting all the layers in the phase E structure.",
keywords = "DHMS phase, High pressure, Hydrogen sites, Neutron diffraction, Phase E",
author = "Naotaka Tomioka and Takuo Okuchi and Narangoo Purevjav and Jun Abe and Stefanus Harjo",
year = "2015",
month = "12",
day = "24",
doi = "10.1007/s00269-015-0791-4",
language = "English",
pages = "1--9",
journal = "Physics and Chemistry of Minerals",
issn = "0342-1791",
publisher = "Springer Verlag",

}

TY - JOUR

T1 - Hydrogen sites in the dense hydrous magnesian silicate phase E

T2 - a pulsed neutron powder diffraction study

AU - Tomioka, Naotaka

AU - Okuchi, Takuo

AU - Purevjav, Narangoo

AU - Abe, Jun

AU - Harjo, Stefanus

PY - 2015/12/24

Y1 - 2015/12/24

N2 - Hydrogen site positions and occupancy in the crystal structure of dense hydrous magnesium silicate (DHMS) phase E were determined for the first time by pulsed neutron powder diffraction. A fully deuterated pure phase E powder sample, which had space group (Formula presented.) and lattice parameters of a = 2.97065(8) Å and c = 13.9033(4) Å, was synthesized at 15 GPa and 1100 °C. Through quantitative evaluation of refined structure parameters obtained with sufficient spatial resolution and very high signal-to-background ratio, we conclude that the O–D dipoles in the refined phase E structure are tilted by 24° from the direction normal to the layers of edge-shared MgO6 octahedra (octahedral layers). The tilted dipole structure of phase E is in remarkable contrast to that of brucite, Mg(OH)2, which has dipoles exactly normal to the octahedral layer. This contrast exists because the O–Si–O bonding unique in the phase E structure connects two adjacent octahedral layers and thereby reduces the interlayer O···O distance. This shrinkage of the interlayer distance induces the tilting of the O–D dipole and also generates unique O–D···O hydrogen bonding connecting all the layers in the phase E structure.

AB - Hydrogen site positions and occupancy in the crystal structure of dense hydrous magnesium silicate (DHMS) phase E were determined for the first time by pulsed neutron powder diffraction. A fully deuterated pure phase E powder sample, which had space group (Formula presented.) and lattice parameters of a = 2.97065(8) Å and c = 13.9033(4) Å, was synthesized at 15 GPa and 1100 °C. Through quantitative evaluation of refined structure parameters obtained with sufficient spatial resolution and very high signal-to-background ratio, we conclude that the O–D dipoles in the refined phase E structure are tilted by 24° from the direction normal to the layers of edge-shared MgO6 octahedra (octahedral layers). The tilted dipole structure of phase E is in remarkable contrast to that of brucite, Mg(OH)2, which has dipoles exactly normal to the octahedral layer. This contrast exists because the O–Si–O bonding unique in the phase E structure connects two adjacent octahedral layers and thereby reduces the interlayer O···O distance. This shrinkage of the interlayer distance induces the tilting of the O–D dipole and also generates unique O–D···O hydrogen bonding connecting all the layers in the phase E structure.

KW - DHMS phase

KW - High pressure

KW - Hydrogen sites

KW - Neutron diffraction

KW - Phase E

UR - http://www.scopus.com/inward/record.url?scp=84951768794&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84951768794&partnerID=8YFLogxK

U2 - 10.1007/s00269-015-0791-4

DO - 10.1007/s00269-015-0791-4

M3 - Article

AN - SCOPUS:84951768794

SP - 1

EP - 9

JO - Physics and Chemistry of Minerals

JF - Physics and Chemistry of Minerals

SN - 0342-1791

ER -