Jean‐Alexis Hernandez
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View article: Observation of a mixed close-packed structure in superionic water
Observation of a mixed close-packed structure in superionic water Open
The study of superionic (SI) water has been a highly active research area since its theoretical prediction. Despite significant experimental and computational efforts, its melting curve and the stability of different oxygen lattices remain…
View article: Dynamic compression of glassy GeO$2$ up to the TPa range and first observation of shock induced crystallization
Dynamic compression of glassy GeO$2$ up to the TPa range and first observation of shock induced crystallization Open
In this work we present an extensive study of glassy GeO$_2$ under laser induced dynamic compression. New VISAR and SOP data provide the extension of Hugoniot EoS up to the TPa range for this material including temperature measurements. Re…
View article: New Constraints on the Melting Temperature and Phase Stability of Shocked Iron up to 270 GPa Probed by Ultrafast X-Ray Absorption Spectroscopy
New Constraints on the Melting Temperature and Phase Stability of Shocked Iron up to 270 GPa Probed by Ultrafast X-Ray Absorption Spectroscopy Open
Studying the properties and phase diagram of iron at high-pressure and high-temperature conditions has relevant implications for Earth’s inner structure and dynamics and the temperature of the inner core boundary (ICB) at 330 GPa. Also, a …
View article: Structural evolution of liquid silicates under conditions in Super-Earth interiors
Structural evolution of liquid silicates under conditions in Super-Earth interiors Open
Molten silicates at depth are crucial for planetary evolution, yet their local structure and physical properties under extreme conditions remain elusive due to experimental challenges. In this study, we utilize in situ X-ray diffraction (X…
View article: Insights on dense silicate melts from shock-compression coupled to in situ X-ray probes
Insights on dense silicate melts from shock-compression coupled to in situ X-ray probes Open
Molten silicates existing at depth play an important role in planetary evolution. Yet, understanding the local structure and properties of liquid silicates under extreme pressure and temperature remains challenging due to the inherent comp…
View article: Ab Initio Atomistic Simulations of Ca‐Perovskite Melting
Ab Initio Atomistic Simulations of Ca‐Perovskite Melting Open
Melting curves of Ca‐perovskite (pure CaSiO 3 ) were determined by ab initio density functional theory, using two solid‐liquid coexistence methods and two free energy approaches, in the form of thermodynamic integration and two‐phase therm…
View article: Diamond formation kinetics in shock-compressed C─H─O samples recorded by small-angle x-ray scattering and x-ray diffraction
Diamond formation kinetics in shock-compressed C─H─O samples recorded by small-angle x-ray scattering and x-ray diffraction Open
Extreme conditions inside ice giants such as Uranus and Neptune can result in peculiar chemistry and structural transitions, e.g., the precipitation of diamonds or superionic water, as so far experimentally observed only for pure C─H and H…
View article: Analyzing Melts and Fluids from Ab Initio Molecular Dynamics Simulations with the UMD Package
Analyzing Melts and Fluids from Ab Initio Molecular Dynamics Simulations with the UMD Package Open
We develop a Python-based open-source package to analyze the results stemming from ab initio molecular-dynamics simulations of fluids. The package is best suited for applications on natural systems, like silicate and oxide melts, water-bas…
View article: Analyzing melts and fluids from ab initio molecular dynamics simulations\n with the UMD package
Analyzing melts and fluids from ab initio molecular dynamics simulations\n with the UMD package Open
We develop a Python-based open-source package to analyze the results stemming\nfrom ab initio molecular-dynamics simulations of fluids. The package is best\nsuited for applications on natural systems, like silicate and oxide melts,\nwater-…
View article: Lactation and gestation controls on calcium isotopic compositions in a mammalian model
Lactation and gestation controls on calcium isotopic compositions in a mammalian model Open
Lactation and gestation are among the physiological events that trigger the most intense changes in body calcium (Ca) fluxes. Along with the composition of the animal 2021 diet, these events are suspected to impact the Ca isotopic composit…
View article: Exploring the deep interior of ice giants with shock-compression experiments and ab initio simulations: The case of metallic ammonia 
Exploring the deep interior of ice giants with shock-compression experiments and ab initio simulations: The case of metallic ammonia  Open
<p>Ammonia is predicted to be one of the major components in the depths of the ice giant planets Uranus and Neptune. Their dynamics, evolution, and interior structure are insufficiently understood and models rely imperatively on data…
View article: Metallization of Shock-Compressed Liquid Ammonia
Metallization of Shock-Compressed Liquid Ammonia Open
Ammonia is predicted to be one of the major components in the depths of the ice giant planets Uranus and Neptune. Their dynamics, evolution, and interior structure are insufficiently understood and models rely imperatively on data for equa…
View article: X-ray powder diffraction in reflection geometry on multi-beam kJ-type laser facilities
X-ray powder diffraction in reflection geometry on multi-beam kJ-type laser facilities Open
An ultrafast x-ray powder diffraction setup for laser-driven dynamic compression has been developed at the LULI2000 laser facility. X-ray diffraction is performed in reflection geometry from a quasi-monochromatic laser-generated plasma x-r…
View article: Melting Curve and Isostructural Solid Transition in Superionic Ice
Melting Curve and Isostructural Solid Transition in Superionic Ice Open
The phase diagram and melting curve of water ice is investigated up to 45 GPa and 1600 K by synchrotron x-ray diffraction in the resistively and laser heated diamond anvil cell. Our melting data evidence a triple point at 14.6 GPa, 850 K. …
View article: Direct Observation of Shock‐Induced Disordering of Enstatite Below the Melting Temperature
Direct Observation of Shock‐Induced Disordering of Enstatite Below the Melting Temperature Open
We report in situ structural measurements of shock‐compressed single crystal orthoenstatite up to 337 ± 55 GPa on the Hugoniot, obtained by coupling ultrafast X‐ray diffraction to laser‐driven shock compression. Shock compression induces a…
View article: X-ray absorption near edge spectroscopy study of warm dense MgO
X-ray absorption near edge spectroscopy study of warm dense MgO Open
We report time-resolved X-ray Absorption Near Edge Spectroscopy (XANES) measurements of warm dense MgO. We used a high power nanosecond pulse to drive a strong uniform shock wave into an MgO sample, and a picosecond pulse to generate a bro…
View article: Multidisciplinary Constraints on the Abundance of Diamond and Eclogite in the Cratonic Lithosphere
Multidisciplinary Constraints on the Abundance of Diamond and Eclogite in the Cratonic Lithosphere Open
Some seismic models derived from tomographic studies indicate elevated shear‐wave velocities (≥4.7 km/s) around 120–150 km depth in cratonic lithospheric mantle. These velocities are higher than those of cratonic peridotites, even assuming…
View article: Equation of state and optical properties of shock-compressed C:H:N:O molecular mixtures
Equation of state and optical properties of shock-compressed C:H:N:O molecular mixtures Open
Water, ethanol, and ammonia are the key components of the mantles of Uranus and Neptune. To improve structure and evolution models and give an explanation of the magnetic fields and luminosities of the icy giants, those components need to …