Microstructure of energetic crystals - grain by grain via rocking curve

Incorporation of improved particle qualities reduces the sensitivity of plastic bonded explosives. The mechanisms that cause this effect are far from being clear. Therefore the microstructures of the energetic cyclic nitramine RDX have been investigated by means of powder X-ray diffraction, comparing so called reduced sensitivity (RS-RDX or I-RDX) to conventional samples. The investigations revealed significant differentiations where "best quality" was found with I-RDX followed by RS-RDX and last RDX. The results give evidence to the hypothesis, that the sensitivity of samples is influenced by the microstructure, where size/strain broadening is related to higher sensitivity. Problems originating from poor orientation statistics of coarse powders have been overcome by measuring rocking curves combined with statistical evaluation. The method gains from information of many crystallites displayed "grain by grain" during rocking the powder sample. Besides, each displayed peak stems from a tiny diffracting volume - the domain -, which reduces peak broadening due to divergence. The method shall be used for comparison and characterization of the microstructure of coarse powders, where grinding would strongly impact the parameters to be investigated.