Abstract
Because of their high surface/volume ratio which may allowed self-healing processes, mesoporous materials could be tolerant materials to radiation damage defects [1]. To investigate this topic, mesoporous and nonporous sol-gel silica thin films (e~100 nm) deposited on Si substrates [2] were irradiated with gold ions of medium energies from 0.5 MeV to 12 MeV. X-ray reflectivity measurement and SEM observations were used to monitor the porous network of the thin films. Infrared measurement was used to characterize the silica network. These characterizations show an evolution of the porous network of the materials depending on the irradiation conditions (fluence, energy of ions) and the initial parameters of the porous network (pore size, porous volume). A total compaction is achieved for a fluence of about 2×1014 cm-2 (~5×1021 keV.cm-3) (figure 1)[3]. The process of mesoporosity collapse seems different according to the irradiation regime (nuclear versus electronic). The sol-gel mesoporous and nonporous samples exhibit a delayed radiation damage compared to material elaborate by classical route, which indicates that sol-gel materials are more radiation tolerant from this point of view. The presentation aims to discuss these different observations, and clarified the role of the interfacial surface on the healing of the defects created by irradiation. From another point of view, the sensitivity of these mesoporous structures to the radiation damage opens interesting prospects for obtaining self-conditioning materials.