An impact structure 1400 m in diameter, formed by a bolide impact, has been discovered on Baijifeng Mountain in Tonghua City in Northeast China’s Jilin province. The impact structure takes the form of a cirque-shaped depression on the top of the mountain and is located in a basement mainly composed of Proterozoic sandstone and Jurassic granite. A large number of rock fragments composed mainly of sandstone, with a small amount of granite, are distributed on the top of Baijifeng Mountain. Planar deformation features (PDFs) have been found in quartz in the rock and mineral clasts collected from the surface inside the depression. The forms of the PDFs indexed in the quartz include among others, {101̄3}, {101̄2}, and {101̄1}. The presence of these PDFs provides diagnostic evidence for shock metamorphism and the impact origin of the structure. The impact event took place after the Jurassic Period and probably much later.

The recent report of superconductivity in nitrogen-doped lutetium hydride (Lu-H-N) at 294 K and 1 GPa brought hope for long-sought-after ambient-condition superconductors. However, the failure of scientists worldwide to independently reproduce these results has cast intense skepticism on this exciting claim. In this work, using a reliable experimental protocol, we synthesized Lu-H-N while minimizing extrinsic influences and reproduced the sudden change in resistance near room temperature. With quantitative comparison of the temperature-dependent resistance between Lu-H-N and the pure lutetium before reaction, we were able to clarify that the drastic resistance change is most likely caused by a metal-to-poor-conductor transition rather than by superconductivity. Herein, we also briefly discuss other issues recently raised in relation to the Lu-H-N system.

Topochemical reactions are a promising method to obtain crystalline polymeric materials with distance-determined regio- or stereoselectivity. It has been concluded on an empirical basis that the closest intermolecular C⋯C distance in crystals of alkynes, d_(C⋯C)min, should reach a threshold of ∼3 Å for bonding to occur at room temperature. To understand this empirical threshold, we study here the polymerization of acetylene in the crystalline state under high pressure by calculating the structural geometry, vibrational modes, and reaction profile. We find d_(C⋯C)min to be the sum of an intrinsic threshold of 2.3 Å and a thermal displacement of 0.8 Å (at room temperature). Molecules at the empirical threshold move via several phonon modes to reach the intrinsic threshold, at which the intermolecular electronic interaction is sharply enhanced and bonding commences. A distance–vibration-based reaction picture is thus demonstrated, which provides a basis for the prediction and design of topochemical reactions, as well as an enhanced understanding of the bonding process in solids.

A material described as lutetium–hydrogen–nitrogen (Lu-H-N in short) was recently claimed to have “near-ambient superconductivity” [Dasenbrock-Gammon et al., Nature 615, 244–250 (2023)]. If this result could be reproduced by other teams, it would be a major scientific breakthrough. Here, we report our results of transport and structure measurements on a material prepared using the same method as reported by Dasenbrock-Gammon et al. Our x-ray diffraction measurements indicate that the obtained sample contains three substances: the face-centered-cubic (FCC)-1 phase (Fm-3m) with lattice parameter a = 5.03 Å, the FCC-2 phase (Fm-3m) with a lattice parameter a = 4.755 Å, and Lu metal. The two FCC phases are identical to the those reported in the so-called near-ambient superconductor. However, we find from our resistance measurements in the temperature range from 300 K down to 4 K and the pressure range 0.9–3.4 GPa and our magnetic susceptibility measurements in the pressure range 0.8–3.3 GPa and the temperature range down to 100 K that the samples show no evidence of superconductivity. We also use a laser heating technique to heat a sample to 1800 °C and find no superconductivity in the produced dark blue material below 6.5 GPa. In addition, both samples remain dark blue in color in the pressure range investigated.

Water has remarkable effects on the properties of mantle rocks, but, owing to the high temperatures in the mantle, uncertainties remain about how and how much water is transported into the deep Earth. Recent studies have shown that stishovite and post-stishovites as high-pressure phases of SiO₂ have the potential to carry weight percent levels of water into the Earth’s interior along the geotherm of the subducting oceanic crust. As slabs are subducted to the deepest mantle, dehydration of these dense hydrous silica phases has the potential to change the physicochemical properties of the mantle by reducing melting points, forming new high-pressure phases, and enhancing the oxygen fugacity heterogeneity of the lower mantle.

Hydrogen (H) is the most abundant element in the known universe, and on the Earth’s surface it bonds with oxygen to form water, which is a distinguishing feature of this planet. In the Earth’s deep mantle, H is stored hydroxyl (OH^-) in hydrous or nominally anhydrous minerals. Despite its ubiquity on the surface, the abundance of H in the Earth’s deep interior is uncertain. Estimates of the total H budget in the Earth’s interior have ranged from less than one hydrosphere, which assumes an H-depleted interior, to hundreds of hydrospheres, which assumes that H is siderophile (iron-loving) in the core. This discrepancy raises the questions of how H is stored and transported in the Earth’s deep interior, the answers to which will constrain its behavior in the deep lower mantle, which is defined as the layer between 1700 km depth and the core–mantle boundary.

Born’s valence force-field model (VFM) established a theoretical scheme for calculating the elasticity, zero-point optical mode, and lattice dynamics of diamond and diamond-structured solids. In particular, the model enabled the derivation of a numerical relation between the elastic moduli and the Raman-active F_2g mode for diamond. Here, we establish a relation between the diamond Raman frequency ω and the bulk modulus K through first-principles calculation, rather than extrapolation. The calculated K exhibits a combined uncertainty of less than 5.4% compared with the results obtained from the analytical equation of the VFM. The results not only validate Born’s classic model but also provide a robust K–ω functional relation extending to megabar pressures, which we use to construct a primary pressure scale through Raman spectroscopy and the crystal structure of diamond. Our computations also suggest that currently used pressure gauges may seriously overestimate pressures in the multi-megabar regime. A revised primary scale is urgently needed for such ultrahigh pressure experiments, with possible implications for hot superconductors, ultra-dense hydrogen, and the structure of the Earth’s core.