Chemical Approach to the Radiolysis of Polyphosphate Glass. I. Effects of Sb(III, V), Mo(V, VI) and U(IV, VI) Ions

Abstract

The yields of radiation-induced electrons and holes trapped in the glass matrix are easily determined by introducing metal ions, such as Sb, Mo, and U ions, into water-soluble NaPO3 polymer glass. Doping 1 mol % of these ions of a lower oxidation state wholly prevents the trapping of holes and results in oxidation to their higher oxidation states. A reaction in the reverse direction also occurs for the same ions of a higher oxidation state, which are converted into a lower one by reduction. This radiation-induced redox reaction has a minimum yield at a dopant composition corresponding to Sb2O4 for Sb(III)–Sb(V), Mo6O17 for Mo(V)–Mo(VI), and U3O8 for U(IV)–U(VI) redox couples. The largest effective volume among these ions for capturing the holes is for Sb(III). In a high-dose region (1020 to 1021 eV/g), the yields of the redox products of these ions increase logarithmically with the γ-dose absorbed. This makes it difficult to determine the G-value of the redox products precisely. The approximate values are in an order of magnitude of 0.1 atom per 100 eV absorbed.