Calorimetric Study of Glass Structure Modification Induced by alpha Decay

R7T7-type glass samples doped with different concentrations of 244Cm and stored for different time periods to produce different levels of accumulated radiation damage were analyzed by differential scanning calorimetry to better understand the structural evolution of R7T7 nuclear glass due to the accumulation of alpha radiation damage. The stored energy and fictive temperature were observed to increase as a function of the alpha decay dose. The stored energy saturates at about 10^18 alpha decays•/g, whereas the fictive temperature continues to increase and saturates at about 6–7 10^18 alpha decays•/g. This discrepancy was interpreted in terms of different effects of energy lost during alpha decay on the glass structure due to electronic stopping and nuclear stopping. This study demonstrates that the stored energy is affected by both phenomena, whereas the fictive temperature variation depends mainly on elastic collisions. The increase of fictive temperature with the cumulative alpha dose is direct evidence that the energy lost by recoil nuclei induces the formation of a new structure similar to a fast-quenched glass.JRC.E.3-Materials researc