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Iron polyphosphate glasses resist attack by water, can dissolve large concentrations of species that are otherwise insoluble in borosilicate glass melts, and can be processed at relatively low temperatures (1000‐1200°C), and so are viable hosts for vitrifying hazardous and radioactive wastes. The properties of iron polyphosphate glasses depend on the distributions of phosphate anions and the nature of the bonds between those anions and various metal polyhedra, and quantitative information can be obtained about those structures using a variety of spectroscopic, diffraction, and chromatographic techniques. This structural information helps explain compositional trends in properties, including dissolution rates, electrical conductivity, thermal properties and crystallization tendency. Studies of waste forms made with low activity and high level wastes are reviewed and related back to an understanding of the structures and properties of simpler iron polyphosphate glasses.

Resorbable glasses with nominal molar compositions of 20Na₂O·30[(1−x)CaO·xSrO]∙50P₂O₅, wherex = 0, 0.25, 0.50, 0.75, and 1, were prepared and characterized. With the replacement of CaO by SrO, the molar volume, refractive index, and coefficient of thermal expansion increased, and the glass transition temperature, crystallization temperature, and viscosity decreased. The replacement of CaO by SrO decreased the dissolution rate in 37°C water by nearly an order of magnitude. Resorbable glass fibers drawn from melts of the 20Na₂O·30CaO·50P₂O₅glass exhibited decreasing transmission of laser light (632 nm) in a predictable way as the fiber dissolved in a phosphate buffer solution. This demonstrated that these glasses could be used to produce resorbable fibers for temporary biosensing or therapeutic applications.