Structure and crystallization behavior of Al containing glasses in the CaO–B2O3–SiO2 system

Abstract

The aim of the present work is to investigate the effects of Al₂O₃ content on both the structure and crystallization behavior of CaO–B₂O₃–SiO₂ (CBS) glass composition using NMR, FT-IR and DSC. The density experimental results showed that the density (ρ) of glasses decreased linearly with increasing Al₂O₃ content, while the molar volume (V_m) of the glasses increased linearly. The NMR revealed that the Al occurred in the forms of Al^IV, Al^V and Al^VI units. With the increasing Al₂O₃ content, the amount of Al species show little change, the relative amount of B^IIIa and B^IIIs units increases while the B^IV units decrease, and the Q⁴ structural units increases clearly but the Q³ decreases. Further, crystallization peaks of CBS glasses shift to higher temperatures, indicating that Al₂O₃ addition can suppress crystallization of CBS glasses.