Effect of molybdenum on structural features and thermal properties of iron phosphate glasses and boron-doped iron phosphate glasses

The variations of structure and thermal properties in iron phosphate glasses and boron-doped iron phosphate glasses due to MoO3 addition up to 50 mol% were investigated and compared in detail. The results show that MoO3 depolymerizes the phosphate networks resulting in a higher connectivity of the networks through [MoO4] units and the formation of Mo-O-P bonds diversifies the cross-linking of the glass networks, leading to the conversion of long phosphate chains to pyrophosphate units and/or orthophosphate units. These structure variations cause the decrease of glass transition temperature, thermal stability and glass formation ability of iron phosphate glasses. Moreover, the MoO3 loading, thermal stability and glass formation ability of iron phosphate glasses were improved by boron. The reasons on the improved properties are also explained and analyzed. The obtained conclusions provide researchers with the role of Mo in structure and properties of phosphate glasses for Mo containing nuclear waste immobilization. (C) 2020 Elsevier B.V. All rights reserved.