استكشف المجموعة الواسعة من العناوين المتاحة.

Producing metallic hydrogen has been a great challenge in condensed matter physics. Metallic hydrogen may be a room-temperature superconductor and metastable when the pressure is released and could have an important impact on energy and rocketry. We have studied solid molecular hydrogen under pressure at low temperatures. At a pressure of 495 gigapascals, hydrogen becomes metallic, with reflectivity as high as 0.91. We fit the reflectance using a Drude free-electron model to determine the plasma frequency of 32.5 ± 2.1 electron volts at a temperature of 5.5 kelvin, with a corresponding electron carrier density of 7.7 ± 1.1 × 1023 particles per cubic centimeter, which is consistent with theoretical estimates of the atomic density. The properties are those of an atomic metal. We have produced the Wigner-Huntington dissociative transition to atomic metallic hydrogen in the laboratory.

The absence of electrical resistance exhibited by superconducting materials would have enormous potential for applications if it existed at ambient temperature and pressure conditions. Despite decades of intense research efforts, such a state has yet to be realized . At ambient pressures, cuprates are the material class exhibiting superconductivity to the highest critical superconducting transition temperatures (T ), up to about 133 K (refs.  ). Over the past decade, high-pressure 'chemical precompression' of hydrogen-dominant alloys has led the search for high-temperature superconductivity, with demonstrated T approaching the freezing point of water in binary hydrides at megabar pressures . Ternary hydrogen-rich compounds, such as carbonaceous sulfur hydride, offer an even larger chemical space to potentially improve the properties of superconducting hydrides . Here we report evidence of superconductivity on a nitrogen-doped lutetium hydride with a maximum T of 294 K at 10 kbar, that is, superconductivity at room temperature and near-ambient pressures. The compound was synthesized under high-pressure high-temperature conditions and then-after full recoverability-its material and superconducting properties were examined along compression pathways. These include temperature-dependent resistance with and without an applied magnetic field, the magnetization (M) versus magnetic field (H) curve, a.c. and d.c. magnetic susceptibility, as well as heat-capacity measurements. X-ray diffraction (XRD), energy-dispersive X-ray (EDX) and theoretical simulations provide some insight into the stoichiometry of the synthesized material. Nevertheless, further experiments and simulations are needed to determine the exact stoichiometry of hydrogen and nitrogen, and their respective atomistic positions, in a greater effort to further understand the superconducting state of the material.

One of the long-standing challenges in experimental physics is the observation of room-temperature superconductivity . Recently, high-temperature conventional superconductivity in hydrogen-rich materials has been reported in several systems under high pressure . An  important discovery leading to room-temperature superconductivity is the pressure-driven disproportionation of hydrogen sulfide (H S) to H S, with a confirmed transition temperature of 203 kelvin at 155 gigapascals . Both H S and CH readily mix with hydrogen to form guest-host structures at lower pressures , and are of  comparable size at 4 gigapascals. By introducing methane at low pressures into the H S + H precursor mixture for H S, molecular exchange is allowed within a large assemblage of van der Waals solids that are hydrogen-rich with H inclusions; these guest-host structures become the building blocks of superconducting compounds at extreme conditions. Here we report superconductivity in a photochemically transformed carbonaceous sulfur hydride system, starting from elemental precursors, with a maximum superconducting transition temperature of 287.7 ± 1.2 kelvin (about 15 degrees Celsius) achieved at 267 ± 10 gigapascals. The superconducting state is observed over a broad pressure range in the diamond anvil cell, from 140 to 275 gigapascals, with a sharp upturn in transition temperature above 220 gigapascals. Superconductivity is established by the observation of zero resistance, a magnetic susceptibility of up to 190 gigapascals, and reduction of the transition temperature under an external magnetic field of up to 9 tesla, with an upper critical magnetic field of about 62 tesla according to the Ginzburg-Landau model at zero temperature. The light, quantum nature of hydrogen limits the structural and stoichiometric determination of the system by X-ray scattering techniques, but Raman spectroscopy is used to probe the chemical and structural transformations before metallization. The introduction of chemical tuning within our ternary system could enable the preservation of the properties of room-temperature superconductivity at lower pressures.

High pressure plays an increasingly important role in both understanding superconductivity and the development of new superconducting materials. New superconductors were found in metallic and metal oxide systems at high pressure. However, because of the filled close-shell configuration, the superconductivity in molecular systems has been limited to charge-transferred salts and metal-doped carbon species with relatively low superconducting transition temperatures. Here, we report the low-temperature superconducting phase observed in diamagnetic carbon disulfide under high pressure. The superconductivity arises from a highly disordered extended state (CS4 phase or phase III[ CS4 ]) at ∼6.2 K over a broad pressure range from 50 to 172 GPa. Based on the X-ray scattering data, we suggest that the local structural change from a tetrahedral to an octahedral configuration is responsible for the observed superconductivity.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The absence of electrical resistance exhibited by superconducting materials would have enormous potential for applications if it existed at ambient temperature and pressure conditions. Despite decades of intense research efforts, such a state has yet to be realized 1 , 2 . At ambient pressures, cuprates are the material class exhibiting superconductivity to the highest critical superconducting transition temperatures ( T c ), up to about 133 K (refs.  3 – 5 ). Over the past decade, high-pressure ‘chemical precompression’ 6 , 7 of hydrogen-dominant alloys has led the search for high-temperature superconductivity, with demonstrated T c approaching the freezing point of water in binary hydrides at megabar pressures 8 – 13 . Ternary hydrogen-rich compounds, such as carbonaceous sulfur hydride, offer an even larger chemical space to potentially improve the properties of superconducting hydrides 14 – 21 . Here we report evidence of superconductivity on a nitrogen-doped lutetium hydride with a maximum T c of 294 K at 10 kbar, that is, superconductivity at room temperature and near-ambient pressures. The compound was synthesized under high-pressure high-temperature conditions and then—after full recoverability—its material and superconducting properties were examined along compression pathways. These include temperature-dependent resistance with and without an applied magnetic field, the magnetization ( M ) versus magnetic field ( H ) curve, a.c. and d.c. magnetic susceptibility, as well as heat-capacity measurements. X-ray diffraction (XRD), energy-dispersive X-ray (EDX) and theoretical simulations provide some insight into the stoichiometry of the synthesized material. Nevertheless, further experiments and simulations are needed to determine the exact stoichiometry of hydrogen and nitrogen, and their respective atomistic positions, in a greater effort to further understand the superconducting state of the material. A nitrogen-doped lutetium hydride was synthesized under high-pressure high-temperature conditions and, following full recoverability, examination along compression pathways showed evidence of superconductivity at room temperature and near-ambient pressures.

Not provided.

One of the long-standing challenges in experimental physics is the observation of room-temperature superconductivity 1 , 2 . Recently, high-temperature conventional superconductivity in hydrogen-rich materials has been reported in several systems under high pressure 3 – 5 . An  important discovery leading to room-temperature superconductivity is the pressure-driven disproportionation of hydrogen sulfide (H 2 S) to H 3 S, with a confirmed transition temperature of 203 kelvin at 155 gigapascals 3 , 6 . Both H 2 S and CH 4 readily mix with hydrogen to form guest–host structures at lower pressures 7 , and are of  comparable size at 4 gigapascals. By introducing methane at low pressures into the H 2 S + H 2 precursor mixture for H 3 S, molecular exchange is allowed within a large assemblage of van der Waals solids that are hydrogen-rich with H 2 inclusions; these guest–host structures become the building blocks of superconducting compounds at extreme conditions. Here we report superconductivity in a photochemically transformed carbonaceous sulfur hydride system, starting from elemental precursors, with a maximum superconducting transition temperature of 287.7 ± 1.2 kelvin (about 15 degrees Celsius) achieved at 267 ± 10 gigapascals. The superconducting state is observed over a broad pressure range in the diamond anvil cell, from 140 to 275 gigapascals, with a sharp upturn in transition temperature above 220 gigapascals. Superconductivity is established by the observation of zero resistance, a magnetic susceptibility of up to 190 gigapascals, and reduction of the transition temperature under an external magnetic field of up to 9 tesla, with an upper critical magnetic field of about 62 tesla according to the Ginzburg–Landau model at zero temperature. The light, quantum nature of hydrogen limits the structural and stoichiometric determination of the system by X-ray scattering techniques, but Raman spectroscopy is used to probe the chemical and structural transformations before metallization. The introduction of chemical tuning within our ternary system could enable the preservation of the properties of room-temperature superconductivity at lower pressures. Room-temperature superconductivity is observed in a photochemically synthesized ternary carbonaceous sulfur hydride system at 15 °C and 267 GPa.