Structural evolution of CeO ₂-doped alkali boroaluminosilicate glass and the correlation with physical properties based on a revised structural parameter analysis

Abstract

CeO ₂ ruptures Si(B)–O bonds in reedmergnerite- and danburite-like groups with cerium ion balance charged units enhancing network interconnectivity.

Abstract

Alkali boroaluminosilicate glasses with composition of 56SiO ₂–20B ₂O ₃–3Al ₂O ₃–8Na ₂O–8K ₂O–5BaO containing 0–9 mol% cerium oxide (CeO ₂) were synthesized at 1500 °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 CeO ₂, 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 CeO ₂ below 3% are absorbed by reedmergnerite- and danburite-like groups producing one non-bridging oxygen (NBO) on the silica tetrahedrals and disconnecting tetrahedral borate [BO ₄] from tetrahedral silicate [SiO ₄]. Addition of CeO ₂ above 3% allows the additional oxygen to combine with reedmergnerite- and danburite-like units producing two NBOs on [SiO ₄] and also one or two NBOs on trigonal planar borate [BO ₃] at the expense of [BO ₄]. Further addition of CeO ₂ 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 CeO ₂ 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 CeO ₂-doped borosilicate radiation resistant glasses.