Gamma radiation-induced defects in KCl, MgCl2, and ZnCl2 salts at room temperature

Room temperature post-irradiation measurements of diffuse reflectance and electron paramagnetic resonance spectroscopies were made to characterize the long-lived radiation-induced species formed from the gamma irradiation of solid KCl, MgCl2, and ZnCl2 salts up to 100 kGy. The method used showed results consistent with those reported for electron and gamma irradiation of KCl in single crystals. Thermal bleaching of irradiated KCl demonstrated accelerated disaggregation of defect clusters above 400 K, due to decomposition of Cl-3(-). The defects formed in irradiated MgCl2 comprised a mixture of Cl-3(-), F-centers, and Mg+ associated as M-centers. Further, Mg metal cluster formation was also observed at 100 kGy, in addition to accelerated destruction of F-centers above 20 kGy. Irradiated ZnCl2 afforded the formation of Cl-2(-) due to its high ionization potential and crystalline structure, which decreases recombination. The presence of aggregates in all cases indicates the high diffusion of radicals and the predominance of secondary processes at 295 K. Thermal bleaching studies showed that chloride aggregates' stability increases with the ionization potential of the cation present. The characterization of long-lived radiolytic transients of pure salts provides important information for the understanding of complex salt mixtures under the action of gamma radiation.

Automated summary

Post-irradiation measurements of diffuse reflectance and electron paramagnetic resonance spectroscopies at room temperature were conducted to characterize long-lived radiation-induced species formed from gamma irradiation of solid KCl, MgCl2, and ZnCl2 salts up to 100 kGy. The results showed the formation of various defects and clusters in the irradiated salts, indicating high diffusion of radicals and prevalence of secondary processes at 295 K. Thermal bleaching studies demonstrated the stability of chloride aggregates is correlated with the ionization potential of the cations present.