In situ viscosity measurement of silicate melts under high pressure by X-ray photon correlation spectroscopy

2021 Fiscal Year Final Research Report

• Project/Area Number: 17K18813
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Research Field: Earth and planetary science and related fields
• Research Institution: High Energy Accelerator Research Organization
• Principal Investigator: FUNAMORI NOBUMASA 大学共同利用機関法人高エネルギー加速器研究機構, 物質構造科学研究所, 教授 (70306851)
• Project Period (FY): 2017-06-30 – 2022-03-31
• Keywords: SiO2ガラス / 水ガラス / 非晶質 / 相転移カイネティクス

Outline of Final Research Achievements

In this study, we obtained the following results on the dynamics of the water-silicate system.
For water glasses (Na2O-SiO2-H2O system), the origin of the characteristic low-Q diffraction peak, which is the key to understanding their structure, is the Na-Na correlation in Na2O-rich clusters. Upon pressurization up to several tens of thousands of atmospheres, the structure of water glasses becomes homogeneous and the peak disappears. A model is proposed for the phase transition kinetics of amorphous materials, formulated in terms of energy levels and activation energy ranges, which successfully reproduces various experimental data on the phenomenon of permanent densification of SiO2 glass.

Free Research Field

放射光地球科学

Academic Significance and Societal Importance of the Research Achievements

マグマの振る舞いを理解する上で、水－ケイ酸塩系の混和－不混和の相転移は重要である。水ガラスに関する研究成果は、この相転移の際の構造変化に関する直接的な情報を与えるものである。また、マグマの振る舞いを理解する上で、液体の相転移ダイナミクスは重要である。非晶質の相転移カイネティクスに関する研究成果は、ガラスを対象としており、液体の相転移カイネティクスのモデルの検討に繋がるものである。