Magnetic resonance studies on radiation-induced point defects in mixed oxide glasses. I. Spin centers in B2O3 and alkali borate glasses

Radiation-induced spin centers in vitreous boron trioxide and alkali borate glasses were studied using pulsed EPR. Electrons and holes in these glasses are trapped on valence alternation defects, undercoordinated O (holes) and overcoordinated O (electrons). The local environment around these defects has major effect on spin parameters of the corresponding spin centers. The electronic and atomic structure of spin-1/2 centers and their diamagnetic precursors is analyzed using semiempirical and ab initio calculations. 58 refs.