Experimental Study of Pressure-induced Structural Changes in Silicate Glasses to >100 GPa

硅酸盐岩浆是地球储层中最有效的热量和物质载体，在广泛的地质过程中发挥着重要作用。 硅酸盐岩浆是高压物体，形成于现今地球深处的火山、洋中脊、俯冲带和热点之下，或形成于早期地球的岩浆海洋深处。 硅酸盐岩浆在高压条件下发生结构变化，了解硅酸盐岩浆中压力引起的结构变化对于了解硅酸盐岩浆在地球深部的行为非常重要。 研究人员开发了新的双级高压装置，结合同步加速器X射线测量，以研究硅酸盐玻璃中压力引起的结构变化，硅酸盐玻璃是硅酸盐岩浆的模拟材料，在相当于地球地幔最低部分的100 GPa高压条件下。 在用户设备中建立新的高压实验技术（光束线16-BM-B，高级光子源中的HPCAT）不仅有助于地球和行星科学的研究，而且还有助于物理学和材料科学以及工程学等各个科学领域的研究，以及研究生和年轻博士后研究人员的教育活动。本项目旨在通过实验研究压力-在100 GPa的高压条件下诱导SiO2和硅酸盐玻璃的结构变化。 大体积样品是高压条件下X射线衍射测量硅酸盐玻璃结构的关键。 研究人员开发了一种新的双级巴黎-爱丁堡型大体积压力机，以产生高达100 GPa的高压，大样品体积。 硅酸盐玻璃的结构将通过原位多角度能量色散X射线衍射在高压下测量。 该项目将为理解在地球深部地幔至核幔边界的压力条件下硅酸盐岩浆中压力引起的结构变化提供重要的实验约束，方法是：（1）获得100 GPa下硅酸盐玻璃结构的第一个实验数据，（2）建立了Si-O配位数与氧填充分数的关系，并对压力-诱导硅酸盐玻璃的结构变化，以应用于地球上的硅酸盐岩浆？s深的内部。

Silicate magmas are the most efficient carriers of heat and matter throughout Earth's reservoirs, and play an important role in a wide range of geological processes. Silicate magmas are high pressure objects, formed at depth in the present Earth beneath volcanoes, mid-ocean ridges, subduction zones, and hotspots, or in the deep magma ocean in the early Earth. Silicate magmas undergo structural changes at high pressure conditions, and knowledge of the pressure-induced structural changes in silicate magmas is important to understand behavior of silicate magmas in the Earth's deep interior. The investigator developed new double-stage high-pressure apparatus combined with synchrotron X-ray measurement, to study pressure-induced structural changes in silicate glasses, which is an analogue material of silicate magmas, at high pressure conditions to 100 GPa corresponding to the lowermost part of the Earth's mantle. Establishing the new high-pressure experimental technique in a user facility (the beamline 16-BM-B, HPCAT in the Advanced Photon Source) contributes to researches not only in Earth and planetary sciences but also in various scientific fields such as physics and material sciences as well as engineering, and to educational activities for graduate students and young postdoctoral researchers.This project aims to experimentally investigate pressure-induced structural changes in SiO2 and silicate glasses at high pressure conditions to 100 GPa. Large volume sample is vital for accurate measurement of the structure of silicate glasses at high pressure conditions using X-ray diffraction measurement. The investigator developed a new double-stage Paris-Edinburgh type large volume press to generate high pressures to 100 GPa with large sample volume. Structure of silicate glasses will be measured by in situ multi-angle energy dispersive X-ray diffraction at high pressures. This project will provide vital experimental constraints on understanding pressure-induced structural changes in silicate magmas at the pressure conditions of the Earth's deep mantle to the core-mantle boundary by (1) obtaining the first experimental data for structure of silicate glasses to 100 GPa, and (2) establishing relationship between Si-O coordination number and oxygen packing fraction to generalize the pressure-induced structural changes in silicate glasses for application to silicate magmas in the Earth?s deep interior.