Vitrification, crystallization behavior and structure of zinc aluminosilicate glasses

The glass formation, crystallization behavior and structure were investigated in the ZnO-Al2O3-SiO2 system. The boundaries of the glass forming region are defined, indicating the absence of glasses along the ZnO-SiO2 binary and the role of Al to improve glass formation. The crystallization behavior has been clarified for representative glass compositions showing first crystallization of willemite near the ZnO-SiO2 binary and a metastable zinc aluminosilicate solid solution for higher Al2O3/SiO2 content. Gahnite appears as a second phase and is mainly present near the center of the tectosilicate join. Glass structure was studied using Al-27 NMR spectroscopy, neutron and X-ray diffraction and molecular dynamics simulation. Both Al and Zn are shown to be distributed between four-fold and five-fold sites. The proportion of Al-[(4]) is more important near the ZnAl2O4-SiO2 join. A remarkable similar behavior is revealed for the glass forming ability and structural properties between MgO and ZnO aluminosilicate systems.

对ZnO - Al₂O₃ - SiO₂体系的玻璃形成、析晶行为和结构进行了研究。确定了玻璃形成区域的边界，表明在ZnO - SiO₂二元体系中不存在玻璃，以及Al在改善玻璃形成方面的作用。对于具有代表性的玻璃成分，析晶行为已得到阐明，在ZnO - SiO₂二元附近首先析出硅锌矿，对于较高的Al₂O₃/SiO₂含量则形成亚稳的铝硅酸锌固溶体。锌尖晶石作为第二相出现，主要存在于架状硅酸盐连接的中心附近。利用Al - 27核磁共振波谱、中子和X射线衍射以及分子动力学模拟研究了玻璃结构。结果表明，Al和Zn均分布在四配位和五配位位置之间。在ZnAl₂O₄ - SiO₂连接附近，Al - [（4）]的比例更为重要。在MgO和ZnO铝硅酸盐体系之间，玻璃形成能力和结构特性呈现出显著的相似行为。