Putting the squeeze on energetic co-crystals: High-pressure studies of 2(CL-20):HMX and NQ:DNP

摘要

Two energetic co-crystal systems have been investigated under pressure using neutron powder diffraction - 2(CL-20):HMX, and nitroguanidine:2-hydroxy-3,5-dinitropyridine (NQ:DNP). The 2(CL-20):HMX co-crystal was prepared with a ResoDyn LabRAM Resonant Acoustic Mixer using a published method. Neutron diffraction experiments were performed on the PEARL beamline at the ISIS Neutron Source in Harwell, Oxfordshire. Compression was observed in this system up to 3.5 GPa broadly in line with the results of DFT-D calculations, and equations of state were determined from the experimental data. No phase transitions were observed during the experiment. The NQ:DNP co-crystal was prepared by solvothermal co-crystallisation, and neutron diffraction experiments were also performed on the PEARL beamline. A potential phase transition was observed between 1.0 and 1.4 GPa. The crystal structure of this high-pressure phase is currently under investigation.