Lattice Imperfections of Energetic Materials Measured by X-ray Diffraction

The mechanical sensitivity is an important issue for energetic materials and explosives, which has been discussed as a function of lattice defects originated during crystallization. However, hitherto a conclusive correlation was not achieved, because the quantitative measurement of defects is difficult. An approach is made to quantify defects in energetic materials with X-ray diffraction. Samples of HMX were crystallized under varying conditions yielding different defect concentrations. The samples are investigated with X-ray diffraction, SEM, and the densities and the mechanical sensitivities were measured. The SEM delivered information for the characterization of surface defects. Quantitative results were obtained by measurements of the density and the mechanical sensitivity. Both delivered significant deviations of the different HMX samples. X-ray diffraction patterns of the samples were measured with different diffraction geometries, and the widths of diffraction peaks were determined. The data were evaluated with Williamson Hall plots revealing the micro strain for each sample. The seed project shows that X-ray diffraction is capable for detecting qualities of coarse crystals, when suited systems are applied. Moreover, the correlation of micro strain and mechanical sensitivities gives an idea, how far lattice imperfections influence macroscopic properties of energetic materials. The encouraging results give rise for further, refined investigations with an extended variety of crystallization conditions.