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

doi:10.1007/s00269-015-0791-4

Cited by 13 publications

(15 citation statements)

References 35 publications

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“…2(a suitable structural model. The O-D covalent bond distance is 0.817 (3) Å , which is identical to our previous powder diffraction results (Tomioka et al, 2016). The OÁ Á ÁD hydrogen bond distance is 2.088 (3) Å .…”

Section: Refinement Of Structural Parameterssupporting

confidence: 88%

“…The former structure retains most of its hydrogen at around 900 K, while the latter retains it at around 600 K. We consider that the difference in dehydration temperatures between these minerals is related to the difference in their hydrogen bonding strengths. (b) Two equally plausible hydrogen site models that have been adopted so far for DHMS phase E (Tomioka et al, 2016). Each corner of the octahedra is made of an oxygen anion (not shown).…”

Section: Single-crystal Synthesis and Characterizationmentioning

confidence: 99%

“…The hkl reflection intensity dataset was analyzed using General Structure Analysis System (GSAS) software (Larson & Von Dreele, 2004). The initial structural parameters were taken from our previous powder neutron diffraction results (Tomioka et al, 2016), though we did not use any constraints. First, the structural model was fit without D to obtain tentative structural parameters of Mg, Si and O.…”

Section: Refinement Of Structural Parametersmentioning

confidence: 99%

“…In order to locate the hydrogen sites, we previously analyzed the structure of deuterated DHMS phase E using powder neutron diffraction at J-PARC, Japan (Tomioka et al, 2016). Two equally plausible hydrogen site models (normal and tilted O-D dipole models) were derived [ Fig.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Strong hydrogen bonding in a dense hydrous magnesium silicate discovered by neutron Laue diffraction

Purevjav

Okuchi

Hoffmann

2020

Int Union Crystallogr J

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A large amount of hydrogen circulates inside the Earth, which affects the long-term evolution of the planet. The majority of this hydrogen is stored in deep Earth within the crystal structures of dense minerals that are thermodynamically stable at high pressures and temperatures. To understand the reason for their stability under such extreme conditions, the chemical bonding geometry and cation exchange mechanism for including hydrogen were analyzed in a representative structure of such minerals (i.e. phase E of dense hydrous magnesium silicate) by using time-of-flight single-crystal neutron Laue diffraction. Phase E has a layered structure belonging to the space group R 3 m and a very large hydrogen capacity (up to 18% H2O weight fraction). It is stable at pressures of 13–18 GPa and temperatures of up to at least 1573 K. Deuterated high-quality crystals with the chemical formula Mg2.28Si1.32D2.15O6 were synthesized under the relevant high-pressure and high-temperature conditions. The nuclear density distribution obtained by neutron diffraction indicated that the O—D dipoles were directed towards neighboring O2− ions to form strong interlayer hydrogen bonds. This bonding plays a crucial role in stabilizing hydrogen within the mineral structure under such high-pressure and high-temperature conditions. It is considered that cation exchange occurs among Mg2+, D+ and Si4+ within this structure, making the hydrogen capacity flexible.

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Section: Refinement Of Structural Parameterssupporting

confidence: 88%

Section: Single-crystal Synthesis and Characterizationmentioning

confidence: 99%

Section: Refinement Of Structural Parametersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Strong hydrogen bonding in a dense hydrous magnesium silicate discovered by neutron Laue diffraction

Purevjav

Okuchi

Hoffmann

2020

Int Union Crystallogr J

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“…This f-TiZr alloy was successfully applied to experiments involving the generation of high static pressures, which requires the extensive deformation of the hard metal. In addition, the f-TiZr alloy was also used to fabricate a thin-walled micro-sample container, which enabled us to obtain a background-free NPD pattern with a pulsed-neutron source [24,25]. The successful application of the f-TiZr alloy has demonstrated that forged TiZr products may play a complementary role in future neutron scattering research.…”

Section: Discussionmentioning

confidence: 99%

Forge-Hardened TiZr Null-Matrix Alloy for Neutron Scattering under Extreme Conditions

Okuchi

Hoshikawa²,

Ishigaki³

2015

Metals

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For neutron scattering research that is performed under extreme conditions, such as high static pressures, high-strength metals that are transparent to the neutron beam are required. The diffraction of the neutron beam by the metal, which follows Bragg's law, can be completely removed by alloying two metallic elements that have coherent scattering lengths with opposite signs. An alloy of Ti and Zr, which is known as a TiZr null-matrix alloy, is an ideal combination for such purposes. In this study, we increased the hardness of a TiZr null-matrix alloy via extensive mechanical deformation at high temperatures. We successfully used the resulting product in a high-pressure cell designed for high-static-pressure neutron scattering. This hardened TiZr null-matrix alloy may play a complementary role to normal TiZr alloy in future neutron scattering research under extreme conditions.

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Neutron scattering: A subsurface application review

Hosseini

Arif

Keshavarz

et al. 2021

Earth-Science Reviews

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

Cited by 13 publications

References 35 publications

Strong hydrogen bonding in a dense hydrous magnesium silicate discovered by neutron Laue diffraction

Strong hydrogen bonding in a dense hydrous magnesium silicate discovered by neutron Laue diffraction

Forge-Hardened TiZr Null-Matrix Alloy for Neutron Scattering under Extreme Conditions

Neutron scattering: A subsurface application review

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