Pressure-induced structural change of liquid germanate

Hiroshi Arima; Osamu Ohtaka; Akira Yoshiasa

doi:10.4131/jshpreview.15.52

Pressure-induced structural change of liquid germanate

Hiroshi Arima, Osamu Ohtaka, Akira Yoshiasa

Materials Development Division

Research output: Contribution to journal › Review article › peer-review

Abstract

Local structures around germanium in liquid germanate have been investigated by in-situ X-ray absorption measurements up to 9 GPa at 1000°C. Liquid germanate consisting of tetrahedrally coordinated germanium contracts with increasing pressure without significant changes in the local structure up to 2.5 GPa and then shows an abrupt fourfold-sixfold coordination change around 3 GPa. The coordination change is completed below 4 GPa and a high-density liquid consisting of octahedrally coordinated germanium is stable to 9 GPa. GeO₆ octahedron in the high-density liquid is more compressible than that in solids, suggesting the possibility of a density inversion between liquid and solid at higher pressure. By considering the analogy of germanates to silicates, these results give some far-reaching implications for the evolution and dynamics of the Earth's deep interior.

Original language	English
Pages (from-to)	52-59
Number of pages	8
Journal	Review of High Pressure Science and Technology/Koatsuryoku No Kagaku To Gijutsu
Volume	15
Issue number	1
DOIs	https://doi.org/10.4131/jshpreview.15.52
Publication status	Published - 2005

Keywords

Coordination change
Germanate
Local structure
Melt
Synchrotron radiation
XAFS

ASJC Scopus subject areas

Chemistry(all)
Materials Science(all)
Condensed Matter Physics

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title = "Pressure-induced structural change of liquid germanate",

abstract = "Local structures around germanium in liquid germanate have been investigated by in-situ X-ray absorption measurements up to 9 GPa at 1000°C. Liquid germanate consisting of tetrahedrally coordinated germanium contracts with increasing pressure without significant changes in the local structure up to 2.5 GPa and then shows an abrupt fourfold-sixfold coordination change around 3 GPa. The coordination change is completed below 4 GPa and a high-density liquid consisting of octahedrally coordinated germanium is stable to 9 GPa. GeO6 octahedron in the high-density liquid is more compressible than that in solids, suggesting the possibility of a density inversion between liquid and solid at higher pressure. By considering the analogy of germanates to silicates, these results give some far-reaching implications for the evolution and dynamics of the Earth's deep interior.",

keywords = "Coordination change, Germanate, Local structure, Melt, Synchrotron radiation, XAFS",

author = "Hiroshi Arima and Osamu Ohtaka and Akira Yoshiasa",

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AU - Arima, Hiroshi

AU - Ohtaka, Osamu

AU - Yoshiasa, Akira

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N2 - Local structures around germanium in liquid germanate have been investigated by in-situ X-ray absorption measurements up to 9 GPa at 1000°C. Liquid germanate consisting of tetrahedrally coordinated germanium contracts with increasing pressure without significant changes in the local structure up to 2.5 GPa and then shows an abrupt fourfold-sixfold coordination change around 3 GPa. The coordination change is completed below 4 GPa and a high-density liquid consisting of octahedrally coordinated germanium is stable to 9 GPa. GeO6 octahedron in the high-density liquid is more compressible than that in solids, suggesting the possibility of a density inversion between liquid and solid at higher pressure. By considering the analogy of germanates to silicates, these results give some far-reaching implications for the evolution and dynamics of the Earth's deep interior.

AB - Local structures around germanium in liquid germanate have been investigated by in-situ X-ray absorption measurements up to 9 GPa at 1000°C. Liquid germanate consisting of tetrahedrally coordinated germanium contracts with increasing pressure without significant changes in the local structure up to 2.5 GPa and then shows an abrupt fourfold-sixfold coordination change around 3 GPa. The coordination change is completed below 4 GPa and a high-density liquid consisting of octahedrally coordinated germanium is stable to 9 GPa. GeO6 octahedron in the high-density liquid is more compressible than that in solids, suggesting the possibility of a density inversion between liquid and solid at higher pressure. By considering the analogy of germanates to silicates, these results give some far-reaching implications for the evolution and dynamics of the Earth's deep interior.

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KW - Local structure

KW - Melt

KW - Synchrotron radiation

KW - XAFS

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