Structure and crystallization kinetics of PbO–B2O3 glasses

Abstract Structure and crystallization kinetics of PbO–B 2 O 3 glasses containing 10–80 mol% PbO were investigated. The analyses of IR spectra reveal that PbO causes a change in the short-range order structure of the borate matrix. Between 10 ≤ PbO ≤ 20 mol%, PbO only acts as a network modifier. With the increase of PbO content, a progressive conversion of [BO 3 ] to [BO 4 ] units occurs and this promotes the formation of boron–oxygen rings, composed of the connection of bridge oxygen between [BO 3 ] and [BO 4 ] units. When the content is over 60 mol%, PbO plays the role of glass former. Four possible structure models have been suggested to explain the effects of PbO on glass network: (a) three coordinated boroxol rings modified by Pb 2+ ; (b) formation of Pb O B covalent bands; (c) bridge networks between [BO 3 ] and [BO 4 ] units; (d) complex structures of Pb 2+ modified boron–oxygen rings and chains. Moreover, The crystallization kinetics of PbO–B 2 O 3 glasses was characterized by DSC analyses. When PbO ≥ 50 mol%, the increase of PbO leads to a decrease of thermal stabilities of the glasses. The increase of B 2 O 3 contributes to the increase trends to crystallization of glasses.