Structural evolution of CeO2-doped alkali boroaluminosilicate glass and the correlation with physical properties based on a revised structural parameter analysis

摘要

Alkali boroaluminosilicate glasses with composition of 56SiO(2)-20B(2)O(3)-3Al(2)O(3)-8Na(2)O-8K(2)O-5BaO containing 0-9 mol% cerium oxide (CeO2) were synthesized at 1500 degrees C using a conventional melt-quench method. Structural evolution of the as-prepared glasses was studied using infrared and Raman spectroscopy and the glasses' physical properties were characterized. The structural parameter based on the Yun, Dell and Bray model was revised by factoring multiple oxides, including CeO2, into the computation of the ratio of alkali oxide to boron trioxide, and was used to describe the glasses' structural states divided into three categories with 3-4% as the critical content that marks the onset of drastic variations in glass structure and properties. The addition of CeO2 below 3% are absorbed by reedmergnerite-and danburite-like groups producing one non-bridging oxygen (NBO) on the silica tetrahedrals and disconnecting tetrahedral borate [BO4] from tetrahedral silicate [SiO4]. Addition of CeO2 above 3% allows the additional oxygen to combine with reedmergnerite-and danburite-like units producing two NBOs on [SiO4] and also one or two NBOs on trigonal planar borate [BO3] at the expense of [BO4]. Further addition of CeO2 beyond 5% will cause the extra NBOs to gradually combine with the disconnected boron triangles to form boron tetrahedrals in addition to continuous depolymerization of the Si-O network. Network depolymerization, enhanced linkage by charge compensation and improved compactness because of close packing are proposed as the cause of diverse variation trends in physical properties in the presence of CeO2 below and above 3-4%, respectively. The revised structural parameter analysis is explainable by the correlation between the observed structural evolution and the physical properties, and thus, can be a useful reference for constituents' regulation of CeO2-doped borosilicate radiation resistant glasses.