All articles tagged with #high pressure
Scientists have identified a new, metastable form of ice, designated ice XXI, which forms under extreme pressure at room temperature. This discovery reveals complex freezing pathways that bypass traditional routes, offering new insights into water behavior in high-pressure environments.
Lawrence Livermore researchers used laser-driven shocks on tiny diamond samples to reproduce the extreme pressures and temperatures found deep in Neptune and Uranus, melting diamond while recording its atomic structure, temperature, density and reflectivity. The work suggests slower initial shocks could improve fuel compressibility and boost energy yield in inertial confinement fusion, offering new atomic-scale benchmarks for modeling ice-giant atmospheres and guiding fusion experiments.
Scientists at LLNL’s Omega laser facility squeezed synthetic diamonds to about one terapascal and temperatures around 7,300 kelvin, watching the crystal lattice vanish as the diamond melted into a dense, metallic liquid carbon with no intermediate phase. The result pins the melting temperature at ~7,300 K at 1 TPa, resolving a roughly 20-year discrepancy with simulations and confirming diamond’s melt into an electrically conducting carbon fluid under extreme conditions.
Scientists used the OMEGA laser to shock tiny diamond samples to 0.6–1.8 terapascals, heating them to about 7,300 kelvin. They observed diamond melting directly into liquid carbon without forming the predicted BC8 phase, with the crystal lattice persisting until melting and a surprising density reversal where solid diamond becomes less dense than its liquid. The findings resolve earlier temperature discrepancies, align with theory, and have implications for inertial confinement fusion models and the study of planetary interiors.
A study on CeSiI, a two‑dimensional van der Waals heavy‑fermion metal, maps its temperature–pressure phase diagram: the Kondo coherence temperature T* drops non‑monotonically with pressure to form a V shape, while antiferromagnetic order is suppressed and a superconducting dome with Tc ≈ 240 mK emerges. The superconductivity sits near magnetic instability and features a large upper critical field, suggesting unconventional pairing. Normal-state transport shows non‑Fermi‑liquid behavior and a diverging effective mass near a quantum critical point, positioning CeSiI as a platform to explore the interplay of strong correlations, Kondo hybridization, magnetism, and unconventional superconductivity in a quasi‑2D system.
Earth’s inner core is a solid iron-rich sphere kept solid not by coolness but by the planet’s crushing pressure, which raises iron’s melting point above the extreme temperatures at the boundary; seismic data and high-pressure experiments place the inner-core boundary at about 5,150 km deep with temperatures roughly in the thousands of kelvin (about 5,400–6,230 K), similar to the Sun’s surface in scale, while the outer core remains liquid. The core is likely an iron-nickel alloy with lighter elements, and the evidence comes from seismology, PREM models, and laboratory experiments rather than any core samples.
In a high‑pressure lab, researchers formed gold hydride by compressing hydrogen with thin gold foil inside a diamond‑anvil cell and heating with X‑ray pulses, creating the first solid compound made of gold and hydrogen in the lab. The result challenges gold’s reputation as inert, shows how extreme conditions can trigger new chemistry, and provides a model system for studying dense hydrogen relevant to planetary interiors and fusion research.
Chinese researchers report synthesizing millimetre-sized bulk hexagonal diamond from oriented graphite under about 20 GPa and 1,300–1,900°C, with diffraction confirming a pure hexagonal carbon phase. They measured a hardness around 114 GPa, slightly higher than typical natural cubic diamond (~110 GPa), and highlight high thermal stability, addressing long-standing debate over hexagonal diamond and suggesting potential for advanced technological uses.
Chinese researchers report the synthesis of a millimeter-sized, phase-pure hexagonal diamond by compressing graphite at 20 GPa and temperatures up to 1,900°C, with X-ray and atomic-scale imaging confirming a hexagonal crystal structure; the diamond is slightly harder and more oxidation-resistant than cubic diamonds, suggesting the long-sought material exists and could have practical uses, though the hardness gain is not the often-cited 50%.
Chinese researchers report millimeter-sized samples of hexagonal diamond (lonsdaleite) produced by compressing graphite at ~20 GPa and 1300–1900 °C, with X-ray diffraction peaks that conclusively confirm the hexagonal structure; tests show the material is stiffer, more oxidation resistant, and slightly harder than conventional cubic diamond, marking the strongest evidence to date in decades-long debates and offering potential uses in tools, thermal management, and quantum sensing.
Researchers compressed gold in a hydrogen-rich environment to megabar pressures (>110 GPa) using a diamond anvil cell and, with ultrafast diffraction from the European XFEL, observed hydrogen incorporation into gold to form a stable gold hydride. The result shows gold’s noble behavior can break down under extreme planetary-core-like conditions, potentially altering models of gas giant interiors and suggesting new metallic hydride materials. The hydride persists only under high pressure; releasing pressure causes hydrogen to escape and gold to revert to its original state.
Under pressures above ~40 GPa and temperatures above ~2,200 K, gold forms a solid gold hydride (Au2Hx) with hydrogen diffusing freely in a hexagonal gold lattice in a superionic state. The compound is reversible, reverting to metallic gold when cooled to ambient conditions, and represents the first confirmed binary solid of gold and hydrogen. This discovery challenges gold’s reputation as chemically inert, with implications for high‑pressure physics, planetary interior modeling, and fusion diagnostics, and was observed using a diamond anvil cell and an X-ray free-electron laser.
Researchers have achieved bulk superconductivity up to 96 K in pressurized bilayer nickelate single crystals synthesized at ambient pressure, overcoming previous growth limitations and revealing structural support for superconductivity in both monoclinic and tetragonal phases, with a correlation between higher Tc and lattice distortion.
Scientists have created a new phase of ice, called XXI, that forms at room temperature under extreme pressure, revealing the complex variety of water's solid states and potentially explaining the composition of icy moons.
Researchers at SLAC accidentally created a new gold hydride compound by heating gold and hydrocarbons under extreme pressures and temperatures, revealing novel chemical behaviors and providing insights into dense hydrogen and fusion processes, with potential applications in planetary science and energy research.