Effect of Sm₂O₃ doped on formation and structure of BaO - B₂O₃ - Al₂O₃ - SiO₂ glass

The glass formation, structure and the structure change effected by heat-treatment of BaO - B₂O₃ - Al₂O₃ - SiO₂ (BBAS) system doped with Sm₂O₃ (BBASS) glasses were investigated by the magic angle spinning nuclear magnetic resonance spectroscopy technology. It is found that, the glass forming region of BBASS glasses expanded firstly then shrunken subsequently, with the content of rare earth oxide increasing. While the extra addition of Sm₂O₃ reached to 30% in mole, the largest glass forming region is attained. In the structure of the BBAS glass, with the addition of BaO, [BO₃] gradually transforms into [BO₄], and the aluminum coordination occurred in the structure gradually transforms from co-existing [AlO₄], [AlO₅] and [AlO₆] to the co-existence of mainly [AlO₄] and less [AlO₅]. In the structure of the BBASS glasses, the Sm₂O₃ has the similar effect as BaO on the alumina coordination sites. While Sm³⁺ accumulates the boron network because of its high field strength, forming a large network structure. Aluminium ion is prior to B³⁺ to enter the stable structure of tetrahedron. Heat-treatment has little effect on the glass structure.