| Abstract Scope |
Recent developments of structure-terahertz (THz) property relationship in borosilicate glasses will be presented. We have studied the effects of the substitution of silicon dioxide for boron oxide and silicon dioxide for sodium oxide in sodium borosilicate glasses. We used several spectroscopies to determine structural changes across the glass compositions and THz time-domain spectroscopy to record the refractive index over the measured bandwidth of ~ 0.1-1 THz. The proposed structure-THz property relationship is based on higher THz refractive index changes correlated to a depolymerized glass network, R> 0.5, a network of SiO4 tetrahedra, danburite and reedmergnerite rings with mixed Si–O–B bridges, and the formation of nonbridging oxygen (nbO) atoms on silicate tetrahedra. A polymerized glass network, R < 0.5, consists of homonuclear boroxol and silica rings within sodium borate and silicate subnetworks. Our results show promise for THz non-destructive evaluation of borosilicate-based glass waste forms in long-term storage. |