Over the past decade, metal halide perovskites have been widely employed as the emerging active-materials for technological innovations, and their research has become one of the central goals in the field of energetic materials. Pressure, a new thermodynamic dimension, can tune microstructure, atomic interactions, electronic orbitals, and chemical bonds of materials, thus serves as a potent means to regulate the structures and properties of metal halide perovskites. In addition, pressure paves a novel avenue for probing and understanding the structure-property relationship. Taking the advantage of diamond anvil cell technology and in situ high-pressure characterization techniques, we have comprehensively summarized the pressure-induced evolutions of metal halide perovskites, encompassing structural phase transitions, order-disorder transitions, amorphization, and local structural evolution. We have examined alterations in properties, such as bandgap, photoluminescence, photoelectronic response, and electrical resistance, and other distinctive high-pressure phenomena. This review systematically analyzes the structure-property interplay within these known materials, and offers insights into the design of future novel materials.

In recent years, pressure-induced physical properties of halide perovskites have attracted significant research interests due to their excellent optical and electronic properties. The study of the structural evolution of perovskite under compression is the foundation and key point of all physical property researches. In this paper, we systematically investigated the structural evolution of the all-inorganic halide perovskite CsGeBr₃ under compression using in situ high-pressure synchrotron X-ray diffraction, in situ high-pressure Raman spectroscopy, ultraviolet/visible/near-infrared spectrophotometry, and first-principles calculations. Our results show that CsGeBr₃ undergoes a reversible rhombohedral $ R3m $ to cubic $ Pm\overline{3}m $ structural phase transition at 1 GPa, and the cubic $ Pm\overline{3}m $ phase maintains at higher pressures. This study provides important scientific basis for further exploration of the properties and applications of halide perovskites under compression.

The perovskite oxide BaMO₃ (M being transition metal) has a complex crystal structure and physical properties. This article systematically summarizes the research progress, focusing on the evolution of crystal structure and physical properties during the M element change process, as well as the structural phase transition, electrical transport properties, and magnetic properties regulation under high-pressure. The influence of M ion radius and synthesis pressure on the evolution process from hexagonal perovskite to perovskite is discussed, and some issues in this field are also discussed. The possible new atomic combinations and structures in this system, as well as the new characteristics and scientific significance of these corresponding materials, are discussed.

Transition metal perovskite materials hold broad prospects for applications in fields such as information technology, energy, and catalysis due to their flexible and diverse crystal structures and rich variety of physical properties. However, the types of transition metal perovskite materials synthesized under conventional conditions are limited. High pressure, as a unique experimental approach, can significantly manipulate atomic distances and elemental configurations in materials. This method offers substantial advantages in synthesizing novel perovskite materials and can induce novel physical properties such as ferroelectricity, magnetism, superconductivity, metal-insulator transition, charge transfer and charge disproportionation by altering electronic structures. In this paper, the preparation of extreme high-pressure materials and high-pressure in-situ measurement techniques, as well as their applications in the synthesis and physical properties control of several types of transition metal perovskite materials are reviewed.

ReO₃ with A-site-vacant perovskite structure undergoes sequential pressure-driven structural transformations. Recently, we found that its high-pressure rhombohedral R-Ⅰ phase (space group R$ \overline{3} $c) is superconducting with an optimal superconducting transition temperature (T_c) of 17 K via high-pressure resistance measurements. To explore new superconductors among Re oxides, in this work we prepared a metastable hexagonal phase of ReO₃ (space group P6₃22) by treating the ReO₃ precursor under 10 GPa and 600 ℃, and characterized its crystal structure, magnetic and electrical transport properties. The results show that P6₃22 phase is not a superconductor down to 2 K at ambient pressure, but displays an anomaly around 250 K in resistivity. High-pressure resistance measurements show that the anomaly at about 250 K in ambient pressure disappears quickly upon compression, and P6₃22 phase shows typical metallic behavior in the whole temperature range without showing any signature of superconductivity down to 1.5 K under pressures up to 62 GPa. In the future, comparative theoretical studies of the hexagonal P6₃22 phase and the R-Ⅰ phase of ReO₃ will help to understand the mechanism of superconductivity in this system.

Exploring the high-pressure crystal chemical behaviors of the PO₆ coordinated octahedron is an important basis for understanding the high-pressure chemistry, the possible occurrence in the lower mantle, and the geochemical cycle of the phosphorus element. In this study, NaPO₃, which is isoelectronic with the major component of the lower mantle MgSiO₃, was studied with the first-principle density functional theory in the pressure range of 0–80 GPa. By ways of geometric optimization and total energy comparison of its ambient pressure β phase (P2₁/n), diopside phase (C2/c), ilmenite phase (R$ \overline 3 $), orthorhombic (Pnma) and cubic (Pm3m) perovskite phases, the structural phase transformation sequence and phase transformation pressures were obtained: P2₁/n→C2/c (2 GPa)→R$ \overline 3 $ (20 GPa)→Pnma (50 GPa), with the unit-cell volume changes of 7.1%, 11.5% and 9.0%, respectively. The phonon dispersion curves of Pm3m-NaPO₃ show remarkable and similar imaginary frequencies at R and M points, while the orthorhombic perovskite structure shows real frequencies throughout the whole Brillouin zone reflecting its dynamic stability. The pressure dependence of lattice constants, P―O bond lengths, P―O―P bond angles and $V_{{\mathrm{NaO}}_{12}} $/$V_{{\mathrm{PO}}_6} $ polyhedron volume ratio of Pnma-NaPO₃ shows that the PO₆ octahedron is regular in the whole calculated pressure range, and the compressibility of NaO₁₂ polyhedron is greater than that of PO₆ octahedron. The electronic structure calculation shows that the 3p and 3s orbitals of P are strongly mixed with 2p orbitals of O in the PO₆ octahedron of Pnma-NaPO₃, and the P―O bond exhibits strong covalency, which plays a key role in stabilizing the orthorhombic perovskite structure.

Mixed-halide perovskites have a variety of excellent photovoltaic properties, including the band gap that is widely tunable with the halogen composition, high photoluminescence quantum yield (PLQY), and so on, making them ideal candidates for the photovoltaic device applications such as solar cells and light-emitting diodes. However, mixed-halide perovskites often encounter phase separation under light illumination, which hinders their wide application in optoelectronics. Therefore, investigating the intrinsic mechanism and controlling methods of their phase separation is crucial to improve their properties for practical applications. In this work, a systematic study of the laser-induced phase separation of CsPb(I_xBr_1−x)₃ nanocrystals with different compositions under strong laser irradiation at different pressures was carried out. We discovered that CsPb(I_xBr_1−x)₃ nanocrystals with different I/Br ratios possess different characteristics of laser-induced phase separation, for example, at ambient pressure, the bromine-rich samples with x<0.1 produce nearly full-bromide CsPbBr₃ phase rapidly and achieve a large PLQY gain; the samples with 0.1<x<0.9 clearly form a new photoluminescence (PL) peak at lower wavelength, which represents the bromine-rich phase generation; while the samples with low bromine content with x>0.9 only produce a broadening of the PL peak as well as a rapid decrease of the PL intensity. By subjecting CsPb(I_xBr_1−x)₃ nanocrystals to a quasi-hydrostatic pressure environment, it was observed that phase separation in bromine-rich samples (x<0.9) rapidly slowed down with increasing pressure and was largely suppressed at a mild pressure of about 0.1 GPa, while phase separation in samples with low bromine content was enhanced with increasing pressure. These findings provide an effective and practical way to understand and overcome the problem of application of relevant photoelectric devices in intense light environments.

Based on the density functional theory (DFT), first-principles calculations were performed to investigate the electronic structures and optical properties of graphene/MoS₂ heterostructures at several different twist angles. The results indicate that the twisted graphene/MoS₂ heterostructures still preserve some characteristics inherent in monolayer structure. Near the Fermi level, the characteristic linear dispersion band structure of graphene layer is retained, and the direct bandgap (E_g) at the Dirac cone is influenced by interlayer rotation modulation. The bandgap of MoS₂ layer exhibits a high sensitivity to layer thickness that the indirect bandgap continuously increases with the increase thickness. At a twist angle of 10.9°, the maximum value of E_g reaches 11.67 meV. The calculated differential charge density result indicates that with the interlayer rotations the Mo―S bond length is changed by the electron transfer between Mo and S atoms, resulting in a increasing of S-S interlayer distance. Simultaneously, the carrier concentration of graphene is increased when it forms a heterostructure with MoS₂. The rotation at the heterojunction interface increases the hole-doped carrier concentration to 9.2×10¹² cm⁻², approximately six times higher than that without twist angle. The results of the optical property calculations for the heterostructures indicate that at a twist angle of 27.0°, its absorption edge undergoes a redshift to the lower energy by 0.233 eV. At a twist angle of 10.9°, the absorption edge undergoes a blue shift, moving towards the higher energy by 0.116 eV. Within the visible light range, the loss function of graphene/MoS₂ heterostructure decreases by 0.007. This study can provide a theoretical basis for the design of new rotation graphene heterostructures optical nanodevices.

In this work, plate-impact experiments, postmortem characterizations and one-dimensional hydrodynamic simulations were conducted to investigate the spall behavior of Cr-Ni-Mo steel under complex shock loading paths. Multi-layer flyers were utilized to generate the complex shock-release-reloading paths. Re-closed spall plane and mitigated damage zones were observed after recompression. Voids nucleate at the austenite grain boundaries and packet boundaries, which is consistent with the observations in single-shock experiments. The damage behavior is characterized by a mixed mode with both transgranular and intergranular characteristics. Moreover, notable impedance mismatch between different flyer layers can lead to the absence of reloading signal in the free surface velocity profiles. These findings can provide us insights into the spall behavior of Cr-Ni-Mo steel under complex loading conditions.

Triply periodic minimal surface (TPMS) structural material is widely used in many fields as a porous medium with high porosity and high energy absorption efficiency. In this paper, the Gyroid and IWP structures were used as the design elements, and the Sigmoid function was used to construct the cylindrical transition layer. The outer IWP structure was connected with the inner Gyroid structure, hence the inner and outer nested GIP hybrid cellular structure was designed. Gyroid structure, IWP structure and GIP hybrid structure samples were printed by selective laser melting technology, and the experimental study was performed by direct impact Hopkinson bar. Combined with LS-DYNA software, the numerical simulation of larger impact velocity range was carried out, and the deformation evolution process as well as dynamic stress-strain relationship of the specimen were analyzed. The results show that the initial peak stress and specific energy absorption of the structure present different strain rate sensitivity. Compared with Gyroid and IWP structures, the stress-strain curves of GIP hybrid structural materials exhibit more obvious strain hardening trend and stronger energy absorption capacity. With the increase in impact velocity, the GIP-2 structure (the impact direction is perpendicular to the axis direction of the cylindrical transition layer) presents lower initial peak stress and larger specific energy absorption than the GIP-1 structure (the impact direction is the same as the axis direction of the cylindrical transition layer), which demonstrates its better impact resistance.

To study the blast-resistant performance and influence factors of high-toughness steel, dynamic response processes of high-toughness (HT) steel flat and stiffened plates were analyzed by numerical simulations and air-blast experiments. Firstly, air-blast experiments for both HT steel and high-strength (HS) steel flat plates were carried out. Comparisons of deformation and damage between HT and HS flat plates for experimental results were performed. Subsequently, deformation and failure processes of HT steel flat plates under close-range air-blast loading were analyzed by nonlinear finite element code LS-DYNA. The validity of numerical simulation method was verified by experimental results. On the basis of verification, the dynamic responses and failure mechanisms of HT steel flat and stiffened plates were further investigated by numerical simulations. Results show that under the close-range air blast of 1 200 g TNT charge and 100 mm stand-off distance, the HT steel flat plate of 10 mm thickness only produces large stretching deformation, whereas the HS steel flat plate of the same thickness appears a big crevasse at its central region. To the same thickness, HT steel flat plates behave obvious superior blast-resistant performance. Under close-range air-blast loading, HT steel flat plates mainly exhibit overall stretching deformation, whereas HT steel stiffened plates produce shear damage along stiffeners. As load intensity increases, three different failure modes occur for HT steel stiffened plates. The local shear stresses in the panel of the HT steel stiffened plate increase with the increase of stiffener’s height. This instead deteriorates the blast-resistant performance of HT steel stiffened plates. This study demonstrates the blast resistance superiority of HT steel, and can provide a technical support for the potential application of HT steel in warship protective structures.

Natural rock masses often contain free boundaries, which can interfere with directional fracturing blasting. To investigate effects of free boundary on directional fracturing blasting, the caustics method and high-speed photography were used to study the crack-tip stress distribution and propagation of directional blast-induced cracks. The reflected P/S waves from the free boundary act on a directional blast-induced crack, and change the crack-tip stress distribution and generate an “arc shaped” crack path. Directional blast-induced crack propagation can be divided into three stages. Stage one: before the action of reflected waves, the crack tip is subjected to the action of a blast-induced gas wedge, resulting in a mode Ⅰ crack that propagates along a straight line. Stage two: under the action of reflected waves, both reflected P and S waves cause the crack tip to be subjected to tension and shear action, resulting in a mixed mode Ⅰ-Ⅱ crack which deflects towards the free boundary. Under reflected P waves, the crack tip produces distorted caustics, and crack-tip stress changes from K-dominated field to non-K-dominated field, while under reflected S waves, crack-tip stress returns to K-dominated field. Stage three: after the action of reflected waves, the crack tip is subjected to inertial action and then returns to a mode Ⅰ crack which propagates along a straight line. On the basis of clarifying effects of reflected P/S waves on the tip of directional blast-induced cracks, a calculation formula for the distance between two directional fracturing blasting holes under the influence of free boundary is derived, providing a theoretical basis for refined directional fracturing blasting.

This article aims to explore the mechanical properties of artificial stones under different conditions. Firstly, dental plaster samples with different ratios (hardness, porosity, powder-to-water ratio, and protein content) were prepared as artificial stones to study the splitting behavior. Secondly, quasi-static Brazilian splitting test were conducted on artificial stones. Finally, a $\varnothing$40 mm split Hopkinson pressure bar (SHPB) was used for dynamic loading, combined with high-speed cameras, digital image correlation (DIC) and other testing methods to observe the damage process during sample splitting and the evolution law of the strain field, and then obtain the strain time history curve of the sample was obtained. Test results show that the quasi-static tensile strength of artificial stones is directly proportional to the hardness and powder-to-water ratio, and inversely proportional to the porosity. And the protein content has little effect on the tensile strength of the material, but it does affect its ductility and brittleness. Under dynamic loading, the artificial stone specimen has an obvious strain rate strengthening effect. There is a linearly increasing relationship between the dynamic enhancement factor for tensile strength and the logarithm of the strain rate. This article provides an effective test method and analysis technique for studying the mechanical properties of artificial stones.

Previous studies revealed that gelatin birds show different mechanical behaviors at different impact velocities. In order to solve the problem that the traditional constitutive methods of gelatin bird cannot be universal in different velocity ranges, the tests of 330 g gelatin birds impacting rigid aluminum alloy plate at 60° and 90° incident angles, covering a velocity range of 70−190 m/s were carried out to record the impact force data and impact morphology. With the increase of velocity, the birds were broken more fully and smaller fragments were observed. The adaptive FEM-SPH (finite element method-smoothed particle hydrodynamics) model of bird was established in LS-DYNA, and a set of constitutive parameters were inverted according to the test results: tangent modulus equals to 1.33 MPa, shear modulus equals to 115.95 MPa, the parameters of Murnaghan equation of state γ equals to 10.49, k₀ equals to 69.77 MPa, bulk modulus equals to 246.4 MPa, failure plastic strain is 1.15, yield stress is 0.21 MPa. The simulation results were in good agreement with the test results, and had higher accuracy compared to the SPH models and the Lagrangian models. The Hugoniot pressure of the adaptive model had the same change trend as the theoretical value, and the stagnation pressure was close to the theoretical value.

To study the influence of cracks with varying lengths and inclination angles on the strength and failure modes of rock-concrete combination, a numerical model of rock-concrete combination with pre-existing cracks was developed using the particle flow code (PFC). The model underwent calibration by comparing its results with indoor test data from prefabricated fractured specimens to select a set of microstructural parameters that closely align with the indoor test results. Subsequently, uniaxial compression tests were conducted on numerical models of rock-concrete composites containing pre-existing fractures. The results indicate that the bearing capacity and elastic modulus of fractured rock-concrete composites increase with the increase of fracture inclination angle. Moreover, functions were established to calculate the peak strength increment for fractures with varying lengths and inclination angles. The fracture length significantly influences the mechanical properties of composite models. The stress state at the rock interface and the confinement effect near the concrete interface determine whether cracks can extend through the interface. By analyzing the distribution of cracks, it was found that the fundamental reasons for crack initiation and propagation are the changes and transfers of the stress field. During the failure process, the failure mode gradually transitions from tension-dominated to macroscopic shear failure. The results reveal the damage evolution of uniaxial compression of single fissure rock-concrete combination material.

To study the crack extension characteristics and energy evolution law of the rock body with different lengths of single fissure under different confining pressures, the mesoscopic parameters were calibrated by use of the indoor triaxial compression test, and the numerical simulation test of PFC^2D particle flow was carried out. The results show that tensile cracks are generated before shear cracks, and both of them grow exponentially; the decrease of the fissure length and the increase of the confining pressure restrain the rapid growth of tensile and shear cracks; when the final failure occurs, the tensile and shear cracks decrease with the increase of the fissure length. The stress is concentrated at both ends of the crack, and there is stress concentration around the crack. Under the same confining pressure, the number of failure blocks of the rock sample decreases with the increment of fissure length. The nature of rock failure is the process of energy storage, dissipation and release, and the rock energy transformation is divided into four stages during the loading process. The increase in fissure length weakens the ability of the rock samples to store strain energy, the total energy decreases, and the confining pressure enhances the ability of the rock samples to store strain energy. The dissipated energy is greater than the strain energy when the rock sample fails, and the dissipated energy decreases with the fissure growth.

Hybrid biomimetic structure design, which integrates the internal structure of a variety of biomaterials, is a new strategy for strengthening and toughening materials in recent years. In this work, carbon fiber reinforced epoxy resin was used to design a new type of “staggered-crossed” composite structure material, which is composed of the “interleaved” structure of nacre shell and the “crossed” structure of strombus shell. Through experimental and theoretical research, it was found that there is a significant difference between the “interleaved” structure of nacre and the “crossed” structure of strombus in the internal load transfer and stress distribution regulation. A simple hybrid mix of the two will produce adverse factors such as local stress concentration and lead to material performance degradation. On this basis, a new type of small angle continuous fiber “crossed” layered biomimetic structure was proposed by further optimizing the composite structure. This structure can optimize the full field stress distribution inside the material, suppress local stress concentration, and form a toughening mechanism that delays the overall structural fracture failure, effectively solving the problem of material performance degradation. The research results are expected to provide a useful reference for solving the contradiction between strength and toughness of materials.

The deformation and energy dissipation mechanism of the aluminum foam sandwich shell under repeated impact loads were investigated by numerical simulation. The effects of radius of curvature, thicknesses distribution of the front/back face sheets, core thickness and impact energy gradient on the repeated impact resistance and energy absorption capacity of the structure were analyzed. It is shown that the deformation of the aluminum foam sandwich shell structure accumulates under repeated impact loads, with local bending deformation of the front face sheet, local compression of the foam core, and global bending deformation of the back face sheet. As impact times increases, the peak impact force and integrated bending stiffness increase, and the impact duration and energy absorption capacity decrease. When each impact energy is the same, for aluminum foam sandwich shell structure, the larger the curvature, the higher the energy absorption capacity, while the midpoint deflections of the front and back face sheets after five repeated impacts are larger than that of the shell structure with smaller curvature. Under five repeated impact loads, when the thickness of the front face is large and the back face is small, the specific energy absorption of the structure is lower, but the midpoint deflection of the back face is smaller. The larger the thickness of the aluminum foam core, the smaller the deflection of the back face of the structure, but the total specific energy absorption is reduced. Under the impact energy with three different gradients, the energy absorption of the structure is the highest when the impact energy is increased successively, and the deflections of the front and back faces are larger, while the energy absorption of the structure is the lowest, and the deflection of the front and back faces is smaller when the impact energy is decreased successively.