Persistence of Covalent Bonding in Liquid Silicon Probed by Inelastic X-ray Scattering

TL;DR

This study uses inelastic x-ray scattering to demonstrate that covalent bonds persist in liquid silicon at high temperature, supporting the existence of a liquid-liquid phase transition, with covalent bonding estimated at 17%.

Contribution

It provides experimental evidence of covalent bonding in liquid silicon and supports the theoretical prediction of a liquid-liquid phase transition.

Findings

Persistence of covalent bonds in liquid silicon.

Agreement between experiments and molecular dynamics simulations.

Evidence supporting a liquid-liquid phase transition.

Abstract

Metallic liquid silicon at 1787K is investigated using x-ray Compton scattering. An excellent agreement is found between the measurements and the corresponding Car-Parrinello molecular dynamics simulations. Our results show persistence of covalent bonding in liquid silicon and provide support for the occurrence of theoretically predicted liquid-liquid phase transition in supercooled liquid states. The population of covalent bond pairs in liquid silicon is estimated to be 17% via a maximally-localized Wannier function analysis. Compton scattering is shown to be a sensitive probe of bonding effects in the liquid state.