Recently, the experimental reports on near room temperature superconductivity of polyhydrides have attracted great attentions, and the theoretical and experimental exploration of new hydrogen-rich superconductors have become a research hotspot in the field of superconductivity. In this paper, we will give a detailed introduction to the experimental progress of binary polyhydride superconductors base on our works.

Since the discovery of superconductivity by the famous physicist Onnes in 1911, people have constantly tried to improve the superconducting transition temperature, and the room-temperature superconductors have also been a century-old dream of human beings. In the course of nearly a hundred years of research, it has constantly updated people’s understanding of superconductivity, enhanced people’s confidence in further improving the superconducting transition temperature and exploring the mechanism of high temperature superconductivity that scientists have discovered copper based superconductors, iron based superconductors and McMillan limit superconductors (like MgB₂). Recently, new hydrogen-rich compounds predicted theoretically and verified experimentally have shown great potential for high temperature superconductivity even room temperature superconductivity, becoming one of the best candidates for room temperature superconductors. It is worth noting that some sulfur hydrides and lanthanum hydrides have superconductivity of more than 200 K under high pressure, leading a research boom of hydrogen-rich compounds and some important theoretical and experimental results have emerged. This paper focuses on the current research progress of hydrogen-rich superconductors, summarizes the crystal structure properties and superconducting properties of new hydrogen-rich compounds from the perspective of different hydrogen structural units and hydrogen bonding characteristics. Five kinds of superconductors in hydrogen-rich compounds are introduced in this paper: interstitial type, ionic type, covalent type, cage type and molecular type, and some general rules affecting the superconducting transition temperature are summarized through comparative analysis of different types of hydrogen-rich compound superconductors. In the end, the current experimental problems to be solved and the future experimental direction are put forward.

Since the discovery of 4.2 K superconductivity in mercury, the search for room-temperature superconductivity has been a hot topic in the field of condensed matter physics. In recent years, scientists have discovered a series of high-temperature superconductivity, represented by covalent H₃S (superconducting transition temperature T_c=203 K) and ionic LaH₁₀ (T_c=250 K) and CaH₆ (T_c=215 K) under high pressures. These works have successively broken superconducting temperature records, opening a new era in search for room-temperature superconductivity in hydrogen-rich compounds. This paper focuses on the progress of theoretical prediction, experimental synthesis, and characterization in binary and ternary hydrogen-rich superconductors with high critical temperature under high pressure. Furthermore, it addresses the challenges and potential avenues in the quest for room-temperature superconductors in hydrogen-rich compounds.

The 3d transition metal dichalcogenide MX₂ (M=Mn, Fe, Co, Ni, Cu, Zn; X=S, Se, Te) with pyrite structure has attracted widespread attention due to their novel physical properties. Among them, the CuX₂ (X=S, Se, and Te) is the only known superconducting system, for which the superconducting transition temperatures (T_c) are 1.5 K (CuS₂), 2.4 K (CuSe₂) and 1.3 K (CuTe₂), respectively. Because they can only be synthesized under high-pressure and high-temperature (HPHT) conditions, earlier reports on CuTe₂ are based on the polycrystalline samples and the detailed physical properties have not been reported on single crystal so far. Here, we synthesized high-quality CuTe₂ single crystals under HPHT conditions at 5 GPa and 900 ℃ using the Kawai type 6/8 two-stage multianvil apparatus and performed detailed crystal, transport, magnetism, and specific heat measurements on its physical properties. The results showed that it belongs to the weakly coupled type-Ⅱ superconductor with T_c about 1.3 K. We systematically compared the relevant superconducting parameters of CuS₂, CuSe₂, and CuTe₂ and further revealed the relationship between their density of state near the Fermi surface and superconducting properties.

Hydrogen has the simplest crystal structure and physical properties at ambient pressure. As the pressure increases, hydrogen undergoes phase transition from insulator to metal, which being called metallic hydrogen. The numerical calculations also indicate that metallic hydrogen has high-temperature super-conductivity, thus the metal hydrogen is also known as the holy grail of physics subject. In this paper, the structural phase transition and superconducting transition temperature (T_c) of solid hydrogen under extreme high pressure 0.5–5.0 TPa were studied by first principles based on density functional theory, which may provide knowledge reserved for subsequent theoretical and experimental studies of metallic hydrogen and its superconductivity. The results show that the phase transition sequence of solid hydrogen under extreme high pressure is: I4₁/amd→oC12→cI16. For the same structure, with the increase of pressure, the electron-phonon-induced interaction decreases, the density of electronic states at the Fermi surface decreases, the vibration frequency increases, and the superconducting transition temperature changes. When the pressure is 2.0 TPa, the oC12 structure of solid hydrogen can obtain the highest T_c of 418 K (coulomb pseudopotential parameter μ^*=0.10). This work provides a reference for further theoretical and experimental research on metallic hydrogen and its superconductivity.

Using first principles density functional theory calculations, the crystal structure, electronic properties, and superconductivity characteristics of the ternary hydride Y-Si-H system under high pressure were investigated. The study revealed the existence of thermodynamically stable phases, including YSiH₇, YSiH₉, YSi₂H₁₂, and YSiH₁₈, and thermodynamically metastable phases, namely YSi₂H₁₃, YSi₂H₁₄, and Y₂SiH₁₇. Electronic properties calculations showed that YSiH₇ is insulator and YSi₂H₁₃ is semiconductor, while the remaining hydrides exhibit metallic properties. Superconducting transition temperatures (T_c) were estimated using the McMillan equation, with YSi₂H₁₂ hosting the highest T_c of 43.5 K at 100 GPa. The dynamic stable pressure of YSi₂H₁₄ can be reduced to 40 GPa, and its T_c is 23.8 K which is twice the highest T_c among binary Y-Si compounds, indicating that introducing H atom into Y-Si system can effectively increase the superconducting transition temperature. Y₂SiH₁₇ exhibits a T_c of 35.8 K at 100 GPa. Spectral function and electron-phonon coupling calculations suggested that in YSi₂H₁₄ and Y₂SiH₁₇, in addition to the H-induced superconductivity from mid-frequency vibrations, low-frequency vibrations of Y also play a significant role for superconductivity.

In this work, we have performed extensive swarm-intelligence structures searching simulations on the RbBSi compounds within the pressure range from 0 to 100 GPa. We have proposed three different phases of RbBSi, of which the stability, the electronic structure and the potential superconductivity were calculated by first-principles calculations. All predicted phases are thermodynamically and dynamically stable within the studied pressure range. The bands of the three phases crossing the Fermi level indicate the structures are all metallic. In addition,P4/nmm-RbBSi is a superconductor withT_c of 14.4 K at ambient pressure. This work extends the understanding and potential application of alkali metal boron-silicide compounds in the field of superconductor.

Recently, a large number of theoretical and experimental studies have reported the emergence of a new sp³ clathrate XB₃C₃, where X represents different metal doping elements. The potential high-temperature superconducting materials have been discovered. New-typical cage material with both strong covalent and superconducting properties has important scientific research significance. In recent years, Ac discovered as the first element of the actinide series, AcH₁₀ has a superconducting transition temperature (T_c) of 251 K, making it a potential room temperature superconductor. Therefore, in this article, first principles density functional theory is used to explore the crystal structure, lattice dynamics, electronic properties, and superconducting properties of AcB₃C₃, AcB₂C₄, and AcB₄C₂ doped with Ac elements based on the cage structures of XB₃C₃, XB₂C₄, and XB₄C₂. Research has found that AcB₂C₄ is difficult to synthesize within the 0–200 GPa range, and AcB₃C₃ exhibits an indirect bandgap semiconductor with a bandgap width of approximately 1.154 eV at atmospheric pressure. Based on the mechanical stability criterion, it can be inferred that AcB₃C₃ and AcB₄C₂ are brittle materials with high hardness and stiffness that are elastically stable. At the same time, AcB₄C₂ exhibits superconducting properties at ambient pressure, with T_c reaching 1.565 K. It has been observed that as pressure increases, the T_c value exhibits a trend of initially decreasing and then increasing. The superconducting mechanism is mainly influenced by intermediate-frequencies phonons, which then shift to the combination of low-frequencies and intermediate-frequencies phonons. This study provides guidance for the experimental synthesis of cage type compound superconducting materials and provides new ideas for exploring superconducting materials with high superconducting transition temperature.

Rare-earth metal superhydrides have attracted much attention because of their high-temperature superconductivity. Since experimental measurements can only determine the structures of rare-earth metal atoms in the superhydrides, first-principles calculations have become an important complementary method for a comprehensive understanding on their structures and physical properties. In this work, the elasticity, lattice dynamics and proton dynamics properties of face-centered cubic CeH₉ and CeH₁₀ with different hydrogen contents but the same Ce lattice structure are investigated comparatively by first-principles calculations. The low hydrogen content is found to favor the elastic and phonon stabilization of face-centered cubic cerium superhydrides expanding to low pressures. At 100–140 GPa, CeH₉ and CeH₁₀ do not have significant proton diffusion at room temperature, but fully transform into the superionic state at 1500 K with diffusion coefficients of 1.6×10⁻⁴−1.2×10⁻⁴ cm²/s and 1.9×10⁻⁴−1.5×10⁻⁴ cm²/s; the diffusion coefficient is positively correlated with temperature and hydrogen content, but negatively correlated with pressure. The findings on the laws of pressure, temperature and hydrogen content affecting the structure and dynamics of cerium superhydrides are obtained, which can be used as a reference for the study of other superhydrides.

The study on damage and fracture of superconducting Nb₃Sn under cyclic loading is an indispensable part of understanding the origin of the irreversible strain limit in Nb₃Sn. This paper uses molecular dynamics simulation to investigate the fracture and deformation damage behavior of polycrystalline and single crystal Nb₃Sn/Nb composite materials under cyclic loading at extremely low temperatures. The effects of strain rate on crack initiation and growth were carefully analyzed in both polycrystalline and single crystal Nb₃Sn/Nb composite materials. The results indicate that slip occurs in single crystal Nb₃Sn/Nb composite materials after cyclic loading. When the local stress at the slip band intersection exceeds the material strength, microcracks initiate at the slip band intersection, leading to fracture failure of the composite material. In contrast, the failure of polycrystalline Nb₃Sn/Nb composite materials is due to the inability of stress at grain boundaries to relax under cyclic loading, which leads to the initiation of microcracks at the grain boundaries and intergranular fracture of the composite material. The analysis of the different damage, fracture, and failure mechanisms of polycrystalline and single crystal Nb₃Sn/Nb composite materials at different strain rates shows that the fracture is brittle at low strain rates. As the strain rate rises, the number of slip bands in the single crystal Nb₃Sn layer increases, enhancing the toughness of the single crystal Nb₃Sn/Nb composite material. Conversely, the influence of grain boundaries on material strength decreases in polycrystalline materials as the strain rate increases. Moreover, polycrystalline Nb₃Sn/Nb composite materials exhibit significant residual strength after local fracture of Nb₃Sn at high strain rates. The research results will contribute to a better understanding of the damage evolution process of Nb₃Sn/Nb composite materials under cyclic loading and offer theoretical guidance for optimizing material performance.

The curved steel-concrete-steel composite structure is a sandwiched structural member, consisting of two curved steel plates and concrete core. Headed studs are used to connect the steel plates and concrete to achieve the composite effect. This type of structure is promising for improving earthquake resistance and anti-blast performance, and has been applied in super high-rise structures, offshore platforms, and nuclear power facilities. This paper conducts experimental and numerical analysis to investigate the damage mode and mechanism of the curved steel-concrete-steel composite slab. Additionally, a parametrically analysis is conducted to explore the impact of blast distance, steel plate thickness, arch heights, and stud spacing on its anti-blast performance. The results indicate that the curved steel-concrete-steel composite structure performs well globally and retains their structural load-bearing capacity without failure after subjecting to blast loading. Increasing the blast distance and steel plate thickness can effectively reduce the concrete damage and the span deflection of the composite slab. Reducing arch heights causes a switch in concrete damage from compression damage to tensile damage, which is more severe and results in larger span deflection of the slab. Although reducing stud spacing increases the concrete plastic damage, it reduces the span deflection of the composite slab. The research results can contribute to the design and applications of curved steel-concrete-steel composite structures.

Zr-based amorphous fragment is an emerging active and efficient destructive element, which will undergo a deflagration reaction and fragmentation when its impact velocity reaches its threshold. The deflagration reaction and fragmentation could greatly increase its behind-armor destructive capability. In order to study the penetration damage mechanism and behind-armor destructive capability of Zr-based amorphous fragments on carbon fiber reinforced composites, a ballistic gun was used to load the spherical fragments to impact 8 and 6 mm thick carbon fiber composite targets at velocities ranging from 496.4 m/s to 1085.8 m/s and 571.4 m/s to 1103.9 m/s, respectively. Then a 2 mm thick LY12 aluminum target plate was arranged behind the target to measure the damage capability under different working conditions. The test results showed that the mainly failure mode of strike face was a coupling failure mode of compression failure and shear failure, and the main failure mode of its back face was a coupling failure mode of tensile failure and the de-sticky splitting of the layer. With the increase of the impact velocity, the proportion of the compression and shear coupling damage of the carbon fiber composite target plate was gradually increased, and the phenomenon of tensile breakage and delamination was gradually decreased. The ballistic ultimate velocities of the fragment for 8 and 6 mm thick carbon fiber composite target were 351.9 and 264.6 m/s, respectively. Behind-armor damage area of the fragment impacted on the 8 mm thick carbon fiber composite target was larger than that of the 6 mm thick carbon fiber target under the same impact velocity. The difference of behind-armor damage area impacted on 8 and 6 mm thick carbon fiber composite targets decreased with the increase of the impact velocity. The behind-armor damage ability of the fragment impacting on the carbon fiber composite target increased with the increase of the impact velocity.

In order to study the effect of charge size on the cook-off characteristics of pressed charges, the calculation model of cook-off process was established for HMX-based pressed charges. The cook-off bombs with different charge sizes were simulated by Fluent software, the effect of charge size on the ignition position, response temperature and response time of pressed charges at different heating rates was calculated. It was found that, at the same heating rate, the response temperature of the charge center is the highest when the length-diameter ratio of HMX-based pressed explosive is 1.0, and the ignition temperature of the charge center decreases with the increase of the length-diameter ratio when the length-diameter ratio is greater than 1.0. When the length-diameter ratio increases to a certain extent, the response temperature of the charge center tends to be a constant. The ignition position of the charge is determined by both the heating rate and the size of the charge, and the ratio of heat transfer between the end face and the periphery face of the charge is inversely proportional to the square of the length-diameter ratio. When the heating rate is slow or the length-diameter ratio is small, the ignition position of the charge is located at the charge center; when the heating rate is fast and the length-diameter ratio is large, the ignition position of the charge is gradually away from the charge center.

In order to investigate the propagation characteristics and thermal shock dynamics of multiple explosive sources gas explosion in complex roadways, numerical simulations were conducted using the Fluent software under three types of dual explosive sources arrangements in the H-type tunnel, including the same side, opposite positions, and diagonal positions. It was found that, after the two explosive sources in the tunnel were ignited simultaneously, its prodromic shock wave propagated along the unburned area of the tunnel. When the two shock waves encountered, the pressure superimposed while the impulse canceled out, and the propagation of flame was blocked by the pressure superposition area, resulting in a slowdown or reversal of the speed. Compared to the single source explosion, the dual explosive sources led to a higher pressure in specific areas such as contact lane, center of bifurcation, and sidewalls. Extreme pressure zones occur at the closed end of the roadway under same-side and diagonal arrangement conditions and at the center of the bifurcation under the opposite arrangement condition.

Local compression of lithium-ion battery (LIB) is the primary form of damage during automotive collisions. In order to investigate the safety performance of 18650 LIBs under local indentation, a custom-made mechanical abuse experimental platform was used to conduct local indentation experiments. The failure mechanism was analyzed through progressive compression, and the failure process and thermal runaway evolution rules were obtained. The effects of the state of charge (SOC), loading velocity, indentation position and indenter size on the safety performance of LIBs were also discussed. The results show that the batteries exhibit a clear thermal runaway pattern under local indentation, and this phenomenon will not occur immediately after the failure, there is a certain reaction time. The SOC is positively correlated with the intensity of thermal runaway, and the failure time of the battery depends on the loading velocity. Moreover, thermal runaway is more likely to occur when the negative electrode end of the battery is damaged, and the temperature is higher when the damaged area is larger. Finally, based on the experimental results, some useful suggestions for the safety design of the battery packs were provided.

To investigate effects of precise millisecond time delay detonation on the layered blasting in a single well completion, the millisecond time between holes within the layer was determined by theoretical calculation, and the JH-2 rock model was used in LS-DYNA software to simulate the precise delayed layered detonation in a single well completion blasting of large-diameter deep holes. Blasting effects of two types of delay time were compared, and the process of rock damage evolution in the wellbore was analyzed, finally field tests were conducted to verify the delay time parameters. The numerical calculation results revealed that through considering a comprehensive analysis of the dynamic rock damage process, the characteristic cross-sectional area of the blasting chamber, and the extent of rock damage, a delay time of 18 ms between layers of blasting proved to be more effective. The optimal delay time was determined by theoretical analysis and numerical simulations. Both field tests and numerical simulations demonstrated that the wellbore formation closely matched in the selected cross-sectional area characteristics, with a similarity ranging from 83.4% to 96.6% and an average similarity of 92.4%. This study highlights that the precise millisecond time delay layered blasting method, obtained through the combination of theoretical analysis, numerical simulation, and field tests (referred to as the “trinity analysis method”), providing reliable and accurate results. It holds practical value and is of significant importance for guiding real-world applications in single blasting well completion projects.