NMR study on structural characteristics of rare earth doped boro-alumino-silicate glasses

The structural characteristics of Re₂O₃ doped B₂O₃- Al₂O₃-SiO₂ glasses and factors such as the component and heat-treating conditions affecting the glass structure were investigated by magic angle spin nuclear magnetic resonance (MAS NMR) spectroscopy and differential thermal analysis (DTA). It is found that, in B₂O₃- Al₂O₃-SiO₂ glass, the boron coordination sites are mainly of trigonal (B(3)) and tetrahedral (B(4)), and the aluminum coordination sites are Al(4), Al(5) and partly of Al(6). With the increase of BaO content in the B₂O₃- Al₂O₃-SiO₂ glass, B(3) gradually changes to B(4), and Al(5), Al(6) changes to Al(4). On the other hand, compared with Ba²⁺, RE³⁺ can accumulate the boron network because of its higher field strength, which results in a large network structure. With the increase of samarium oxide, the silicate coordination Q(3T) will have predominance gradually. Heat-treatment has little effect on the boron and aluminum coordination sites in the glass structure.