Are Nanoporous Materials Radiation Resistant?
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The key to perfect radiation endurance is perfect recovery. Since surfaces are perfect sinks for defects, a porous material with a high surface to volume ratio has the potential to be extremely radiation tolerant, provided it is morphologically stable in a radiation environment. Experiments and computer simulations on nanoscale gold foams reported here show the existence of a window in the parameter space where foams are radiation tolerant. We analyze these results in terms of a model for the irradiation response that quantitatively locates such window that appears to be the consequence of the combined effect of two length scales dependent on the irradiation conditions: (i) foams with ligament diameters below a minimum value display ligament melting and breaking, together with compaction increasing with dose (this value is typically ∼5 nm for primary knock on atoms (PKA) of ∼15 keV in Au), while (ii) foams with ligament diameters above a maximum value show bulk behavior, that is, damage accumulation (few hundred nanometers for the PKA's energy and dose rate used in this study). In between these dimensions, (i.e., ∼100 nm in Au), defect migration to the ligament surface happens faster than the time between cascades, ensuring radiation resistance for a given dose-rate. We conclude that foams can be tailored to become radiation tolerant.
author list (cited authors)
Bringa, E. M., Monk, J. D., Caro, A., Misra, A., Zepeda-Ruiz, L., Duchaineau, M., ... Farkas, D.
complete list of authors
Bringa, EM||Monk, JD||Caro, A||Misra, A||Zepeda-Ruiz, L||Duchaineau, M||Abraham, F||Nastasi, M||Picraux, ST||Wang, YQ||Farkas, D