Growth of nanostructures on surface of NaCl powder under gamma irradiation
Abstract
The work was aimed at studying what kinds of nanostructures grow on the surface of pure NaCl powder under effect of 60Co γ-irradiation at 140 R/s in air at 300 K, taking into account that non-irradiated surface is not perfect and may contain nanophases due to contact with wet air. Indeed, XRD has found 36v%NaCl, 16v%NaC1O3, 33v%NaOH, 14v%NaH and 1v%Na2O, all cubic phases except orthorhombic NaOH. Energy dispersion system in SEM has confirmed deficit of Cl below the stoichiometric ratio Na/Cl. After 60Co γ-irradiation to 105 R the part of Cl-containing phases decreased to 24v% due to additional losses of Cl, while NaH phase increased up to 46v%. The following higher dose 0.7×106 R caused the decrease of NaCl to 8v% (where Cl1-) and some recovery of NaClO3 up to 28v% (where Cl5+), growth of NaH to 50v% and 3v%Na hexagonal. The sizes of phases determined by Scherrer formula vary within 5-100 nm. Such mutual nanophase transformations indicate that Cl does not leave the surface and suggest nuclear reactions 35Cl17 → 18O8 + 16O8 + 1H1 and 37Cl17 → 18O8 + 16O8 + 3T1 under exposure to 1.17 and 1.33 MeV γ-quanta fluxes 2.9×1016 - 1.8×1017cm-2.