High-pressure structural studies of energetic compounds

The phase diagram of the energetic material hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) has been explored using X-ray and neutron diffraction from ambient pressure to 8GPa. Two phases of RDX have been structurally characterized. The high-pressure -polymorph exists above 4GPa while the metastable -polymorph has been isolated from the high boiling point solvent nitrobenzene. Interestingly, neutron diffraction measurements at high pressures and high temperatures show that the -polymorph isolated under ambient conditions is not the same polymorph as can be accessed at high pressures and temperatures.