Storage of toxic heavy metals in phosphate glasses: physical and water durability properties

Phosphate glasses of composition (100−y)[50 P2O5-15 ZnO-(35−x) PbO-x CdO]-yAl2O3 have been prepared and studied. In the alumina-free glasses (y=0), the effect of CdO substitution for PbO involves a strengthening of the glass network with a maximum of the aqueous durability for x values close to 20. For x=20, the addition of Al2O3 in the composition range 0≤y≤8 leads to a progressive increase of the phosphate network reticulation. For y>4, an unexpected change in the properties is observed, which probably results from a cationic rearrangement in the glass structure. For y=8, the chemical durability is equivalent to that of window glass. Such glasses are potential candidates for the storage of toxic heavy metals