Physics Colloquium: Jennifer Ciezak-Jenkins
Dr. Jennifer Ciezak-Jenkins from the U.S. Army Research Laboratory will be the featured speaker at an upcoming Department of Physics and Astronomy colloquium. Her talk is titled, "The Promise and Challenge of Extended Solids of Nitrogen."
The response of nitrogen to extreme conditions has attracted great interest since the predictions that nitrogen would transform into a nonmolecular phase at pressures less than 1 Mbar. As a result, the experimental phase behavior of nitrogen has been well characterized. Of particular interest was the identification of the cubic-gauche single bonded polymeric structure at high pressures and temperatures (>150 GPa, 2000K), which was found to be metastable at room temperature to pressures near 40 GPa. Nitrogen is of particular interest due to its promising potential as a high-energy-density material and it has been suggested its energy release may be roughly three times that of a traditional energetic materials. However, considerable challenges exist before such a capability could be realized, such as addressing the significant pressure-temperature barrier to transition from the molecular to non-molecular form, the conditions of which are not amenable to larger scale production technique; additionally, methods must be developed to increase the metastability to ambient conditions. In an effort to increase the metastability of the extended solid, recent studies have focused on mixing, or doping, the nitrogen with small amounts of secondary gases, such as hydrogen or carbon monoxide. It was been postulated the secondary gas would passivate the terminal ends thus increasing the stability of the nitrogen extended solid. Ciezak-Jenkins's group was the first to demonstrate such an approach could be used successfully to decrease the transition pressure for the formation of the nitrogen extended solid through doping with hydrogen. Although recent studies on nitrogen/hydrogen mixtures by other research groups have also observed several non-molecular nitrogen/hydrogen structures, recovery of these materials to ambient conditions has not yet been demonstrated. In this talk, Ciezak-Jenkins will describe our progress in the study of the synthesis, characterization, and recovery of extended solids of nitrogen from high pressure conditions from nitrogen/carbon monoxide mixtures. She will also detail results from our closely coupled modeling and simulation efforts and discuss how these results help guide our experimental efforts. New opportunities and challenges that have arisen in the course of our studies that will be pursued in the future will also be presented.
Admission is free and open to all.
Department of Physics and Astronomy