Nature of the bonded-to-atomic transition in liquid silica to TPa pressures

TL;DR

This study uses first-principles calculations to analyze the bonded-to-atomic transition in liquid silica at extremely high pressures and temperatures, shedding light on planetary interior conditions and bond dissociation processes.

Contribution

It provides a detailed characterization of the bonded-to-atomic transition in liquid silica at TPa pressures, clarifying the nature of bond dissociation relevant to planetary interiors.

Findings

Strong ionic bonds become short-lived during transition

Transition temperature is sensitive to pressure

Calculated Hugoniots match experimental data

Abstract

First-principles calculations and analysis of the thermodynamic, structural, and electronic properties of liquid SiO$_2$ characterize the bonded-to-atomic transition at 0.1--1.6 TPa and 10$^4$--10$^5$ K (1--7 eV), the high-energy-density regime relevant to understanding planetary interiors. We find strong ionic bonds that become short-lived due to high kinetics during the transition, with sensitivity of the transition temperature to pressure, and our calculated Hugoniots agree with past experimental data. These results reconcile previous experimental and theoretical findings by clarifying the nature of the bond dissociation process in early Earth and "rocky" (oxide) constituents of large planets.