Energetic Materials Frontiers最新文献

Single-bonded polymeric nitrogen (PN) synthesized under high pressure was highly delivered for its valuable application prospects on high-energy-density materials (HEDM) and profound effects for understanding the interaction behavior of simple diatomic. Since the 1980s, polymeric phases of nitrogen have displayed remarkable complexity under extreme conditions of pressure and temperature that fascinated theoreticians and experimentalists. The high-pressure X-ray diffraction (XRD) and Raman spectroscopy experiments on PN made it possible to elucidate their evolution, in particular, to measure important structural information through scientific facilities. Here, the synthesized PN hitherto, including cubic gauche nitrogen (cg-N), layered polymeric nitrogen (LP-N), hexagonal layered polymeric nitrogen (HLP-N), post-layered-polymeric nitrogen (PLP-N), and black phosphorous structure nitrogen (BP–N) are reviewed. The synthesized methods, diagnosed technologies, lattice dynamics, and experimental challenges are introduced, with a particular focus on their structural similarity and lattice dynamic characterization, and the Raman criterion for nitrogen polymerization is also given. Finally, we propose the expectation of developing free-electron laser (FEL) and high-pressure neutron technology which is a potential key in the research of fundamental elements under high pressure.

To better understand the structure-activity relationship and enhance the overall performance of polymer-bonded explosives (PBXs), the neutron and X-ray scattering techniques, which utilize neutron or X-ray radiation as probes, are unique and useful methods for quantifying the inherent hierarchical microstructures and components of PBXs. This review focuses on a series of scattering techniques and their typical applications in PBXs and includes a brief introduction of large neutron and X-ray scientific facilities in China. It describes the basic principles, instrumentation, sample environment, and empirical approaches of small-angle scattering (SAS), neutron reflection (NR), and neutron diffraction (ND). Additionally, it reviews common applications of these scattering techniques in the fields of PBXs. Combining the scattering techniques with complementary methods yields several valuable parameters that account for the microstructural features of PBXs. The combination can be used to establish multi-scale structure-activity relationships of PBXs and optimize the preparation process, numerical simulations, and performance prediction of PBXs. More efforts should be made to (1) gather the comprehensive multi-scale microstructural parameters for certain PBXs and add them to corresponding characteristic databases; (2) further investigate the dependence of the microstructural features on the preparation conditions of PBXs; (3) establish multi-factor correlations between the multi-scale microstructural features and the multiple performances obtained from experiments; (4) incorporate the microstructural parameters into various theoretical computational models.

A simple, mild and efficient method was proposed to construct fused tricyclic skeletons based on Mannich reaction. This work not only develops a new method to construct the tricyclic skeletons effectively, but also provides a new insight into the fused tricyclic skeletons containing flexible ring, which will greatly contribute to the research and development of the tricyclic energetic compounds. The relationship of structure-activity was studied by weak interactions calculation, single crystal structures analysis, electrostatic potentials calculation. The experimental and theoretical investigations suggest that the fused tricyclic skeleton containing flexible ring possesses better thermal stability and can be derivatized more easily compared with the similar aromatic fused tricyclic skeleton. Besides, the energetic derivates based on the fused tricyclic skeleton containing flexible ring possess good comprehensive properties: 2 (D ​= ​7726 ​m ​s⁻¹, p ​= ​22.7 ​GPa) and 4 (D ​= ​8151 ​m ​s⁻¹, p ​= ​26.3 ​GPa). All these results suggest that the fused tricyclic skeleton containing flexible ring is an ideal candidate to construct energetic compounds.

This review provides numerous studies on nitrogen-rich tetracyclic-based heterocyclic energetic materials including oxadiazole, tetrazole, triazole, pyrazole, imidazole and tetrazine. The article mainly describes the construction method of energetic skeleton, explosive modification, and properties of tetracyclic energetic materials. The structure-property relationship was obtained by comparing the properties of a series of nitrogen-rich energetic materials. Finally, authors summarize the synthesis laws of energetic skeletons, which provides reference for the development of energetic materials in the future.

As a full nitrogen energetic anion, pentazolate (cyclo-N₅ˉ) holds great promise in the fields of propellants and explosives. Nowadays, nonmetallic pentazolate salts have received extensive attention as excellent nitrogen-rich energetic materials for their high enthalpies of formation, good oxygen balance, and eco-friendly decomposition products. In this study, a 1,4,5-triaminotetrazolium-based pentazolate salt (TATe⁺N₅ˉ, 8) with a nitrogen content of up to 90.30% was designed and synthesized. Its crystal structure indicates that a large number of hydrogen bonds form a hydrogen-bonded network, and the crystal has a mixed stacking pattern. TATe⁺N₅ˉ, which has a relatively high density (1.64 ​g·cm⁻³), high heat of formation (861.9 ​kJ·mol⁻¹), and excellent detonation performances (detonation velocity: 9487 ​m·s⁻¹, detonation pressure: 32.5 ​GPa), provides new insights into the stability of ultrahigh-nitrogen compounds.

Two new tetrazole ligands were designed and synthesized using simple methods in this study, namely 1H-tetrazole-5-carbohydrazide (HCHT, 1) and 2-amino-5-(1H-tetrazol-5-yl)-1,3,4-oxadiazole (HAOT, 2). Their solvent-free potassium salts [K(CHT)]_n (3) and [K(AOT)]_n (4) are new two-dimensional energetic metal-organic frameworks (EMOFs), and their structures were characterized using nuclear magnetic resonance (NMR), infrared spectroscopy (IR), mass spectrometry (MS), elemental analysis (EA), and single-crystal X-ray diffraction (SXRD). Both compounds 3 and 4 exhibit high decomposition temperatures (T_d) of 314 ​°C and 310 ​°C, respectively and are highly insensitive to impact and friction stimuli (IS ​> ​40 ​J, FS ​> ​360 ​N). The detonation velocity and pressure of 3 were calculated at 9141 ​m ​s⁻¹ and 29.0 ​GPa, respectively, and those of 4 were determined at 8423 ​m ​s⁻¹ and 24.5 ​GPa, respectively. Furthermore, intermolecular interactions in 3 and 4 were analyzed using 2D fingerprint plots with associated Hirshfeld surfaces. In this manner, two thermally stable and insensitive EMOFs were developed based on two new tetrazole ligands.

The equation of state (EOS) for energetic structural materials (ESMs) has been drawn a great attention due to the absent comprehensive understanding on the effect of the shock-induced chemical reaction. In this paper, the shock compression behavior of Ni/Al ESM is investigated by developing the EOS, which mainly considers the effects of the chemical reaction and the reaction products. The chemical reaction is based on the Avram-Erofeev kinetic law and the Arrhenius equation. The study concerns the shock pressure, the relative volume, the temperature, and the chemical reaction during the shock compression. The effects of the initial porosities, the stoichiometric ratios and inert additives were mainly discussed. The results showed that high porosity would induce high temperature rise. Different stoichiometric ratios would produce different temperature rise. When the stoichiometric ratio Ni: Al ​= ​1:1, the temperature rise is highest. In addition, the inert additive material would obviously reduce the temperature rise. Finally, the developed model improved the temperature calculation, compared with the existing model.

This study prepared a series of novel hypergolic fluids based on borohydride ionic liquids and organic superbase using an in situ synthetic method. In these hypergolic fluids, ionic liquids in 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) acted as triggers for the self-ignition of DBN and DBU upon contact with high-concentration hydrogen peroxide (H₂O₂). These hypergolic fluids had high densities (>1.000 ​g ​cm⁻³), low viscosities (as low as 34.03 ​cP), and acceptable ignition delay times (IDT). The ignition processes of the hypergolic fluids with 90% H₂O₂ as an oxidizer were first investigated in this study, and they differed from the previously reported ignition phenomena. Different from the case with white fuming acid (WFNA) as an oxidizer, the ignition processes of hypergolic fluids with 90% H₂O₂ as an oxidizer did not exhibit secondary rebound and splashing and formed a homogeneous mixed layer when the droplets were in contact with 90% H₂O₂. The different ignition processes significantly influenced the properties of hypergolic fluids. Compared with the hypergolic fluids with WFNA as an oxidizer, those with 90% H₂O₂ as an oxidizer showed a shorter IDT (IDT_{min[90% H2O2]=}28.3 ​ms, IDT_min[WFNA]=126 ​ms) and formed stable flames without secondary combustion. These results demonstrate that the in-situ synthesized fuels in this study hold great promise as green fuels in hypergolic propulsion systems.