Positron lifetime spectroscopy of vitreous B2O3

Abstract A comparison is made of the structural data obtained by positron lifetime spectroscopy (PLS) for vitreous B 2 O 3 (v-B 2 O 3 ) and crystalline B 2 O 3 (c-B 2 O 3 ). Samples of v-B 2 O 3 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, B 3 O 6 rings are thought to be formed during slow cooling of v-B 2 O 3 . PLS measurements show that both the intensity value and the long lifetime component ( τ 3 ) associated with positron decay in cavities and lifetime component ( τ 1 ) associated with the positron annihilation in the bulk are different for v-B 2 O 3 and c-B 2 O 3 . The low intensity of τ 3 for c-B 2 O 3 and its high value for v-B 2 O 3 is argued to be due to the presence of different structural units in the two states of B 2 O 3 .