Positron lifetime spectroscopy of vitreous B2O3

A comparison is made of the structural data obtained by positron lifetime spectroscopy (PLS) for vitreous B2O3 (v-B2O3) and crystalline B2O3 (c-B2O3). Samples of v-B2O3 were dried by holding the melt at 1350 K to reduce residual OH groups. Fast quenching and slow cooling were used to obtain glasses having different fictive structures. According to the literature, B3O6 rings are thought to be formed during slow cooling of v-B2O3. PLS measurements show that both the intensity value and the long lifetime component (τ3) associated with positron decay in cavities and lifetime component (τ1) associated with the positron annihilation in the bulk are different for v-B2O3 and c-B2O3. The low intensity of τ3 for c-B2O3 and its high value for v-B2O3 is argued to be due to the presence of different structural units in the two states of B2O3.