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

硅酸盐岩浆是地球储层中热量和物质的最有效载体，在各种地质过程中起着重要作用。硅酸盐岩浆是一种高压物质，形成于现今地球深处的火山、洋中脊、俯冲带和热点之下，或形成于地球早期的深部岩浆海中。硅酸盐岩浆在高压条件下发生结构变化，了解压力诱发的硅酸盐岩浆结构变化对了解地球深部硅酸盐岩浆的行为具有重要意义。研究人员开发了新的双级高压仪器，并结合同步加速器x射线测量，研究了硅酸盐玻璃（硅酸盐岩浆的类似物质）在高压条件下的压力引起的结构变化，高压条件达到100 GPa，对应于地幔的最底部。在用户设备中建立新的高压实验技术（光束线16-BM-B，先进光子源中的HPCAT）不仅有助于地球和行星科学的研究，而且有助于物理、材料科学和工程等各个科学领域的研究，并有助于研究生和年轻博士后研究人员的教育活动。本项目旨在实验研究在高压至100 GPa条件下SiO2和硅酸盐玻璃的压力诱导结构变化。在高压条件下，大体积样品是精确测量硅酸盐玻璃结构的关键。研究者开发了一种新的双级Paris-Edinburgh型大容量压力机，可以在大样本量下产生高达100 GPa的高压。采用原位多角度能色散x射线衍射法在高压下测量硅酸盐玻璃的结构。该项目将通过(1)获得第一个100 GPa以下硅酸盐玻璃结构的实验数据，为了解地球深部地幔至核幔边界压力条件下硅酸盐岩浆的压力诱导结构变化提供重要的实验约束；(2)建立Si-O配位数与氧堆积分数之间的关系，推广硅酸盐玻璃中压力引起的结构变化，应用于地球硅酸盐岩浆。内心深处。

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.