A-site ordered quadruple perovskite oxides with a formula as $\rm AA'_3 B^{\;}_4 O^{\;}_{12}$ exhibit multiple physical properties and superior performances, thus act as important subjects of current condensed matter physics and material science. Compared to the simple ABO₃ perovskite, in the A-site ordered quadruple perovskite three quarters of the A atoms are replaced by transition metal Aʹ, forming ordered A/Aʹ occupancy with a 1∶3 ratio. As a result, the electric and magnetic interactions such as Aʹ-Aʹ and Aʹ-B can occur, leading to novel phenomena and new physics. Here we focus on several representative A-site ordered quadruple perovskites, recall their researches, briefly introduce their structures, physical properties and inner mechanisms, and discuss the opportunities for both fundamental studies and potential applications.

In this paper, we reviewed the recent progress on the high-pressure synthesis of Pb-based simple perovskite compounds PbMO₃ (M=3d transition metals) and the investigation on their physical properties, mainly focusing on the M dependent crystal structure, electronic configuration, magnetism, transport properties, pressure induced structure phase transition, charge transfer and insulator to metal transitions. We also gave a comment on the unresolve problems in this system.

Double perovskite Y₂NiIrO₆ is a ferrimagnetic material with Curie temperature of 192 K. It has drawn wide attention owing to its remarkable exchange-bias effect. Here, we studied the low-temperature crystal structure, electron transport properties and magnetoresistance of Y₂NiIrO₆. The crystal structure under 130 K is almost identical with that of room-temperature. The material shows semiconducting behavior in the temperature range of 130 to 300 K. Above Curie temperature it can be well describe as Efros-Shklovskii variable-range hopping model. Below Curie temperature, a departure occurs due to the forming of long-range ferrimagnetic ordering. It is interesting to find that the magnetic ordering results into negative magneto-resistance. Moreover, giant magnetoresistance up to –10% is induced by cooling field of 7.0 T. This mechanism of this remarkable effect provides a new boulevard to discover new type of giant magneto-resistance materials.

The copper-based rare-earth perovskites La_1–xNd_xCuO₃(0≤x≤1) have been synthesized in the two-stage Walker-type high-pressure apparatus. The refined crystal structure results revealed that La_1–xNd_xCuO₃ (0≤x≤0.4) adopts a rhombohedral structure with the space group $R\overline 3 c $. When 0.5≤x≤0.7, a mixed phase with both $R\overline 3 c $ rhombohedral and Pnma orthorhombic structures was observed in the system. With a further increase in Nd³⁺ doping, the system exhibits a single Pnma orthorhombic phase when x=0.8, 0.9 and 1. A comprehensive structural phase diagram of La_1–xNd_xCuO₃ (0≤x≤1) was established in this study, providing a new material platform for investigating the magnetic properties, metal-insulator transitions, and other physical property evolutions in rare-earth 3d transition metal oxides.

We present a theoretical approach for predicting the electron configuration, polymorph, synthesis condition, and physical properties of complex magnetic double perovskite compounds. Our method is reasonable and computationally efficient, allowing us to identify an antiferromagnetic (AFM) metallic material, namely Mn₂FeOsO₆, with a high AFM Néel transition temperature (T_N). Through extensive analysis, we demonstrate that Mn₂FeOsO₆ possesses a high density of states near the Fermi level and an AFM configuration, resulting in a zero total magnetic moment. Our findings suggest that the expectedT_N of Mn₂FeOsO₆ is as high as 680 K, representing a potential breakthrough in the field of spintronics. We have also constructed a sophisticated magnetic model for this material, and obtained a reasonably reliable magnetic excitation spectrum potentially comparable with neutron scattering spectra. This theoretical approach provides synthesis conditions that are consistent with many synthesized double perovskite compounds in experiments, and it holds promise for the prediction of other complex magnetic configurations. Our study may play a key role in the big data prediction of novel double perovskite materials.

The electrical explosion of metal bridge foil is a key physical process in many fields, e.g. electric guns and slapper detonator. Due to the complexity of material properties, dynamic processes, and effects of geometric configurations, a large amount of earlier theoretical simulations used simplified physical models. In this paper, a three-dimensional electromagnetic-thermal-mechanical model was established. which was a full physical model describing the early behavior of explosive foil. The early thermal expansion process of the explosive foil under large current loading was simulated, and the evolution of magnetic field, current, temperature, expansion speed of the foil was analyzed. The phenomena of angular and linear current diffusions induced by the configuration and the resistivity were observed in the simulation. The temperature distribution in the bridge region obtained from the simulation is qualitatively consistent with experiment and simulation results of literature.

The dynamic mechanical behavior and microstructure evolution of titanium alloy Ti6Al4V under shock compression at temperatures ranging from 25 ℃ to 800 ℃ and strain rates from 2000 s⁻¹ to 7000 s⁻¹ were studied by using a split Hopkinson pressure bar. The temperature dependence and strain rate sensitivity of the material’s mechanical response were analyzed, and a modified Johnson-Cook model that could accurately characterize the plastic flow behavior of the material was developed. The results show that Ti6Al4V exhibited significant strain hardening, strain rate strengthening, strain rate plasticity, and temperature softening effects. With increasing loading temperature and strain rate, the material’s strain hardening effect is weakened. The temperature sensitivity is significantly decreased with increasing loading temperature. The strain rate sensitivity factor is negatively correlated with the loading temperature, and it shows a downward trend as the true strain increased. At high temperatures and high strain rates, fine equiaxial α phase, elongated α phase, and massive α phase replace the initial equiaxial α phase as the typical microstructure features of Ti6Al4V. The modified Johnson-Cook model that considers the effect of rate-temperature coupling and adiabatic temperature rise can accurately predict the plastic flow stress-strain response of Ti6Al4V.

Compared with the traditional reinforced concrete and profiled double-skin composite wall (PDSCW), concrete-infilled double steel corrugated-plate wall (CDSCW) has better axial compressive capacity, lateral flexural stiffness, impact resistance and seismic performance, which has broad application prospect in ship and military field. In this paper, two types of CDSCW specimens were designed and produced. Firstly, the damage modes and dynamic responses of the two specimens were analyzed and compared through near-field explosion test. Secondly, the finite element model of CDSCW was established by using ANSYS/LS-DYNA software. The damage mechanism and explosion response of CDSCW and PDSCW under near-field explosion were studied, and the results were compared with the test results. Finally, effects of concrete thickness, steel plate thickness and charge quantity on the anti-blast performance of corrugated double steel plate composite wall board were analyzed. The results show that, compared with PDSCW, CDSCW with the same concrete and component size (length and width) have greater flexural rigidity, energy dissipation capacity, and better knock resistance performance under near field explosion. Increasing the corrugated depth can effectively improve the anti-blast performance of CDSCW, which provides reference for the design of anti-blast component and related engineering research.

As a new type of energetic material, high-entropy alloys will release a large amount of energy during high-speed impact, which has important application value. A two-stage light gas gun system was used to load the HfZrTiTaNb high-entropy alloys projectile under vacuum environment, and the impact experiment of bearing steel was carried out. The evolution process of response parameters such as flash radiation temperature, gas overpressure, flame propagation velocity and temperature rise of container wall was measured. The energy flow direction during the impact reaction of the high-entropy alloys projectile impacting the target plate was analyzed. The enthalpy of the mixed gas, the flash radiation energy, the absorption energy of the container wall, the enthalpy of the ejected gas and the deformation energy generated by the impact on the target during the impact reaction of the high-entropy alloys in a closed container were quantitatively calculated. The effects of different elements and their contents on the energy release of high-entropy alloys were obtained. The results showed that the energy released by the impact reaction of high-entropy alloys projectiles was mainly absorbed by the quasi-closed container wall. With the increase of Cu or Al content, the unit mass release energy of HfZrTiTaNb based high-entropy alloys increased. At similar impact velocities, the high-entropy alloys containing Cu released more energy per unit mass than the high-entropy alloys containing Al.

To study the influence of crack inclination angle on the mechanical properties and the energy evolution mechanism during the rock failure, a calculation model was constructed based on the particle flow dispersion element numerical platform, and uniaxial compression numerical experiments were conducted on rock samples with different crack inclination angles. The research results indicate that as the crack inclination angle increases, the peak strength and elastic modulus of fractured rocks show a “V” shaped trend of first decreasing and then increasing. When the crack inclination angle is small, the rock sample mainly undergoes shear failure and vertical splitting failure, and the number of tensile and shear cracks mainly increases in a stepped pattern. The larger the crack inclination angle, the more the rock failure mode will transition to a mixture of vertical splitting and shear failure, and the curve of the number of tensile and shear cracks will increase exponentially. As the crack inclination angle increases, the total input energy and elastic strain energy of the rock sample show a trend of first decreasing and then increasing. The larger the crack inclination angle, the faster the increase in dissipated energy, but the lower the final dissipated energy when the rock sample fails. The existence of cracks significantly weakens the energy storage limit, weakens the ability of the rock to absorb and store elastic strain energy, and enhances its energy dissipation ability at peak stress in the rock specimen during compressive failure.

Artificial plastic hinges have been widely used in the seismic research of frame structures, which can control the location of the beam plastic hinges and avoid the continuous collapse of the frame structure due to the damage of beam-column joints in earthquakes. The design goal of “strong column weak beam” can be achieved. An artificial plastic hinge with kinked rebar provides a new idea for structural blast resistance. Established structural static load tests have shown that the kinked rebar has excellent deformation performance. The ultimate load capacity of beam with kinded rebar is not reduced. With the software ANSYS/LS-DYNA and the hybrid finite element modeling approach, a numerical simulation study of reinforced concrete frame structures with different kinked rebar schemes was carried out. The results showed that the beam with kinked rebar can absorb the impact energy, reduce the support reaction, delay the peak reaction force, protect the beam-column joints, limit the damage to beam-slab members, and prevent the continuous collapse of frame structre.

Aiming at the problem of deflection when the projectile obliquely penetrates a multi-layer target, a theoretical calculation model of the projectile deflection caused by the oblique cone structure of the projectile tail is established, and the change rule of the deflection with the tail structure is obtained at the working conditions of the velocity of 0.2−1.2 km/s, the angle of attraction of −30°−20°, the radius of the projectile body of 30–60 mm, and the angle between bevel plane of tail and the projectile shaft of 0°−4°. Moreover, the accuracy of the model is verified by comparing with the test results. The results showed that the tail of the projectile forms a negative deflection moment and the projectile produces a “head down” effect when the tail of the projectile penetrated upward target, and the tail of the projectile forms a positive deflection moment and the projectile produces a “head up” effect when the tail of the projectile penetrated downward target; the deflection moment of vertical axis is about 100 times greater than that of parallel axis. The deflecting moment can be increased by increasing the angle between bevel plane of tail and the projectile shaft, the length of the tail, and the radius of the projectile. Increasing the angle between bevel plane of tail and the projectile shaft is more effective in increasing the deflection moment than increasing the tail length.

The near-seabed explosion shock wave can cause serious damage to such facilities as submarine optical cables and pipelines. The spatiotemporal evolution of the underwater explosion shock wave can be affected by the impedance of different types of substrate. Therefore, it is of great significance to study the near-seabed explosion shock wave load under different substrate conditions. Based on the coupled Eulerian-Lagrangian (CEL) method, a numerical model of near seabed explosion is established to investigate the effect of seabed material on the shock wave load of near seabed explosions. The results show that the seabed material significantly affects the peak pressure of the shock wave within a certain range of measuring point angles of 20°–50°. The reflection effect of the near seabed increases with the increase of the explosion distance ratio within a certain range of measurement point angles of 20°–50°. When the measurement point angle exceeds this range, this phenomenon gradually disappears. The effect regions of these two types of seabed sediment are similar while their reflection coefficients are significantly different. When the seafloor sediment is soft, the reflection coefficient near seafloor ranges from 0.81 to 1.05. However, when the seafloor sediment is hard, the reflection coefficient near seafloor ranges from 0.98 to 1.33. The water depth has little effect on the peak pressure of the shock wave.

The bubble curtain can effectively weaken the influence of underwater shock wave on the surrounding environment. In order to investigate the synergistic effect of air supply volume and bubble curtain layer on the shock wave attenuation of underwater explosion, underwater explosion tests with one layer, two layers and three layers were designed under the air supply volume of 30, 60, and 90 L/min, respectively. The results show that the attenuance of bubble curtain increases with the increase of air supply volume and layer number. When the air supply is small (such as 30, 60 L/min), with the increase of the number of bubble curtain layers, the attenuation efficiency of the peak pressure between adjacent layers becomes worse; when the air supply is large (such as 90 L/min), with the increase of the number of bubble curtain layers, the attenuation efficiency of the peak pressure between adjacent layers becomes better. Combined with the economic benefits of the actual project and the complex underwater environment problems to analyze the attenuation effect of the bubble curtain, it was determined that the two-layer bubble curtain with the air supply rate of 30 L/min was the optimal attenuation scheme, which provides reference and new ideas for related practical engineering problems.

In order to explore the influence of CO₂ and porous materials on methane explosion characteristics, the 100 mm×100 mm×1000 mm explosion pipeline was independently designed. The influence of porosity of different porous materials and CO₂ injection pressure on methane explosion flame structure, flame propagation velocity and explosion overpressure were examined. The results show that: the porous material has two opposite effects on flame wave attenuation and promotion. When the porosity of the porous material is 10 and 20 PPI, it fails to resist the explosion, but when the porosity is 40 PPI, the explosion resistance is evident. CO₂ jet pressure has a certain effect on explosion resistance. When the porous material is 10 and 20 PPI, the peak flame velocity decreases gradually with an increase in CO₂ jet pressure, the maximum attenuation rate is 13.64%, and the maximum attenuation rate of the peak explosion overpressure is 52.83%. According to the variations of flame velocity and pressure, the porosity of the porous material is 40 PPI, and the CO₂ jet pressure is 0.4 MPa, the explosion suppression effect is the optimal.

Three obstacles with different levels of bending strength was selected for experimental research on the impact of hydrogen-methane mixed gas explosions in order to explore the varying environmental hazards of explosion promotion. During the experiment, the images of the flame in the explosion pipeline and the upstream and downstream pressure were collected. Through the analysis of flame images and explosion pressure data, the flow field accelerated by expanding gas after explosion generates eddy currents behind obstacles, and the flow field produces different eddy currents behind obstacles of different materials, which result in the difference of peak flame velocity of gas in the later stage and the difference of explosion overpressure in pipelines. This proves the correlation between the intensity of promoting explosions and the material of obstacles. In the experiments conducted in this paper, there is a proportional relationship between the intensity of promoting explosions and the bending strength of the obstacle. Moreover, after hydrogen was added, the reaction of the gas base was accelerated and the peak explosion pressure in the obstacle pipes of the three materials began to produce obvious differences. It can be concluded that obstacles and rough walls in the environment will affect the gas explosion effect, and the difference is caused by the characteristics of the material itself, and the difference is affected by the combustion rate of the gas itself.