Phase composition, structure, and hydrolytic durability of phosphate glass materials for immobilizing liquid highly level waste rich in-iron-group elements

Abstract

X-ray diffraction and electron microscopy were used to examine phase composition and the distribution of elements in glass materials which simulated the vitrified high-level wastes. The variations in the compositions of forming glass materials due to the high content of iron in the waste (as well as the low contents of nickel and chrome) from sodium-alumina-phosphate to sodium-iron-phosphate caused variations in phase compositions and distributions of elements between the phases. Sodium-alumina-phosphate glass characterized by an increased tendency for crystallization which declined on the substitution of about half of all Al2O3 for Fe2O3 and NiO, and increased again with a subsequent increase in the content of oxides of transition elements. Chrome oxide(III) served as a crystallization catalyst. Substitution of 6 wt % P2O5 for B2O3 increased somewhat the crystallization durability of the glass containing a high amount of Al2O3, but produced no effect in the case of glass with a high content of iron and nickel oxides. The dependence of the hydrolytic durability of glass materials on composition was complicated, but, in general, the durability declined on transition from alumina-phosphate to iron-phosphate glass.