Insight into Structural Variations in CaSiO₃ Glass under High-Pressure.

Pressure-induced structural modifications in silicate melts play a crucial role in controlling dynamic processes in the Earth's deep interiors and other terrestrial planets. In order to understand the origin and significance of deep melt in Earth’s interiors, it is important to obtain laboratory constraints on thermodynamics and physical properties at high-pressure and high-temperature. However, despite their crucial roles in dynamic processes, little is known about the structures of liquid silicates throughout the Earth’s pressure regime because the high-pressure and high-temperature environments entail severe experimental difficulties. Therefore, there were still many issues that needed to be addressed in the study of silicate melts. Here, we investigate CaSiO₃ glass up to ~70 GPa in the diamond anvil cell by using a combination of experimental techniques, including Raman spectroscopy, X-ray scattering, and Brillouin spectroscopy. The detailed structural and property data collected on the CaSiO₃ glass allow us to gain first-hand information on how structural changes affect physical properties and uncover missing links between the structure and physical property relationship for silicate melts and glasses.