PNNL

Abstract

Vanadium-containing glasses have raised interests in several fields such as cathode materials, semiconducting glasses and nuclear waste disposal. The addition of V2O5 in small amounts can alter glass physical properties and chemical durability; however, the structural origins of the impact from V2O5 on properties of multi-component oxide glasses are not clear. We present a comprehensive study that integrates advanced characterization and atomistic simulations to understand the structures and the composition-structure-property (CSP) relationships of a series of vanadium-containing aluminoborosilicate glasses. UV-Vis spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES) have been used to investigate the complex charge state of vanadium as a function of concentration in a series of six-component aluminoborosilicate glasses. High energy X-ray diffraction and molecular dynamics (MD) simulations were performed to extract detailed short- and medium-range atomistic structural information such as bond distance, coordination number, bond angle and network connectivity. It was found that vanadium mainly exists in two charge states V5+ and V4+, with the former dominating in most compositions. Both V5+ and V4+ were found to be in 4-, 5-, and 6-fold coordination environments with a bond distance of around 1.73 Å. The percentage of 4-fold coordinated boron and network connectivity increase with increasing V2O5 (until 5 mol%) but decrease with higher than 5 mol% V2O5. The structural role of vanadium and the effect on glass structure and properties are discussed, providing insights into future studies of sophisticated structural descriptors to predict glass properties from composition and/or structure and aiding the future formulation of borosilicate glasses for nuclear waste disposal and other applications.