Speaker: Professor Colin Pulham, University of Edinburgh

"Putting the Squeeze on Energetic Materials - High-Pressure Structural Studies of Nitramines and Azides"

The performance of energetic materials depends on several factors that include crystal density, detonation velocity, and sensitivity to detonation by stimulus. These in turn are governed by the solid-state structure of the energetic material. In order to model and understand the characteristics and performance of these materials, not only under ambient conditions but also under the extreme conditions of temperature and pressure experienced during detonation, it is essential to obtain detailed structural information at the molecular level. This presentation will describe how advances in the techniques for the collection and analysis of high-pressure X-ray and neutron diffraction data, in combination with spectroscopic data, now permit the accurate determination of the full crystal structure of energetic materials under extreme conditions. Examples will include RDX, CL-20, and some simple inorganic azides. The talk will also illustrate how high-pressure forms of energetic materials can be recovered to ambient pressure, thereby offering the potential for the discovery of new forms with enhanced properties, e.g. increased density, reduced sensitivity, etc.