title: High-pressure structural changes in liquid silica.
abstract: The structural properties of liquid silica at high pressure and moderate temperature conditions, also referred to as the warm dense matter regime, were investigated using time-resolved K-edge x-ray absorption spectroscopy and ab initio calculations. We used a nanosecond laser beam to compress uniformly a solid SiO_{2} target and a picosecond laser beam to generate a broadband x-ray source. We obtained x-ray absorption spectra at the Si K edge over a large pressure-temperature domain to probe the liquid phase up to 3.6 times the normal solid density. Using ab initio simulations, we are able to interpret the changes in the x-ray absorption near-edge structure with increasing densities as an increase in the coordination number of silicon by oxygen atoms from 4 to 9. This indicates that, up to significant temperatures, the liquid structure becomes akin to what is found in the solid SiO_{2} phases.
authors.affiliation: LULI-CNRS, Ecole Polytechnique, CEA, Université Paris-Saclay, F-91128 Palaiseau cedex, France.|Sorbonne Universités, UPMC Univ. Paris 06, CNRS, Laboratoire d'Utilisation des Lasers Intenses (LULI), Place Jussieu, 75252 Paris cedex 05, France.
authors.forename: A
authors.initials: A
authors.lastname: Denoeud
authors.affiliation: LUTH, Observatoire de Paris, CNRS, Université Paris Diderot, 92195 Meudon, France.|Département de Physique Théorique et Appliquée, CEA, 91680 Bruyère-le-Chatel, France.
authors.forename: S
authors.initials: S
authors.lastname: Mazevet
authors.affiliation: Institut de Minéralogie de Physique des Matériaux (IMPMC), Sorbonne Universités, MNHN, UPMC, IRD, Paris, France.
authors.forename: F
authors.initials: F
authors.lastname: Guyot
authors.affiliation: Université Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, Talence F-33405, France.
authors.forename: F
authors.initials: F
authors.lastname: Dorchies
authors.affiliation: Université Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, Talence F-33405, France.
authors.forename: J
authors.initials: J
authors.lastname: Gaudin
authors.affiliation: LULI-CNRS, Ecole Polytechnique, CEA, Université Paris-Saclay, F-91128 Palaiseau cedex, France.|Sorbonne Universités, UPMC Univ. Paris 06, CNRS, Laboratoire d'Utilisation des Lasers Intenses (LULI), Place Jussieu, 75252 Paris cedex 05, France.
authors.forename: A
authors.initials: A
authors.lastname: Ravasio
authors.affiliation: LULI-CNRS, Ecole Polytechnique, CEA, Université Paris-Saclay, F-91128 Palaiseau cedex, France.|Sorbonne Universités, UPMC Univ. Paris 06, CNRS, Laboratoire d'Utilisation des Lasers Intenses (LULI), Place Jussieu, 75252 Paris cedex 05, France.
authors.forename: E
authors.initials: E
authors.lastname: Brambrink
authors.affiliation: LULI-CNRS, Ecole Polytechnique, CEA, Université Paris-Saclay, F-91128 Palaiseau cedex, France.|Sorbonne Universités, UPMC Univ. Paris 06, CNRS, Laboratoire d'Utilisation des Lasers Intenses (LULI), Place Jussieu, 75252 Paris cedex 05, France.
authors.forename: A
authors.initials: A
authors.lastname: Benuzzi-Mounaix