PNNL

Abstract

Electron-irradiation-induced phase separation in a sodium borosilicate glass was studied in-situ by analytical electron microscopy. Distinctly separate phases that are rich in boron and silicon formed at electron doses higher than 4.0 ? 1011 Gy during irradiation. The separated phases are still in amorphous states even at a much high dose (2.1 ? 1012 Gy). It indicates that most silicon atoms remain tetrahedrally coordinated in the glass during the entire irradiation period, except some possible reduction to amorphous silicon. The particulate B-rich phase that formed at high dose was identified as amorphous boron that may contain some oxygen. Both ballistic and ionization processes may contribute to the phase separation.