Response and variation mechanisms of RDX crystals under strong magnetic loading

Abstract

To fully understand the variation in performance of cyclotrimethylenetrinitramine (RDX) crystals under strong magnetic field exposure, the strong magnetic loading of RDX was conducted in both stable and alternating magnetic fields. The morphological changes of RDX crystals exposed to magnetic fields were studied under a scanning electron microscope. Then, the lattice changes of RDX exposed to magnetic fields were analyzed through X-ray diffraction and Raman spectroscopy. Also, the thermal decomposition characteristics of RDX exposed to magnetic fields were determined by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Furthermore, positron annihilation lifetime spectroscopy was performed to characterize the micro defects in RDX after strong magnetic interaction. Finally, molecular dynamics simulation was conducted to calculate the lattice constant, microscopic distribution, initiation bonds, and density of states for the RDX exposed to magnetic fields. The results show that after 10 hours of irradiation with a stable high-intensity magnetic field of 6T, the RDX crystals exhibit more pronounced grooves on their surfaces, and the relative intensity of Raman peaks may change due to the stress generated by magnetic field exposure. Comparatively, an alternating magnetic field of ±6T facilitates the peeling off of small particles on the surface, induces greater strain, and results in surface dislocations. With various pronounced grooves and pores, the surface of RDX crystals exhibits a fish scale-like structure. After the exposure to an alternating magnetic field, significant changes occur to multiple wavenumber positions of the RDX Raman spectrum, indicating a considerable strain on the sample caused by the change in magnetic field. The treatment with a strong magnetic field leads to a significant increase in the number of micro pores measured to be 4–5 nm in RDX samples. According to the calculation results, the structural stability of RDX is higher compared to the RDX without a magnetic field, and the energy gap of the crystal is suppressed by a stronger magnetic field.