Thermal properties of phosphate glasses for salt waste immobilization

Abstract

Vitrification is the most effective method of the hazardous waste immobilization. Toxic elements are incorporated into glass structure. Iron phosphate glasses are presently being considered as a matrix for storage of the radioactive waste which cannot be vitrified using a conventional borosilicate glass. Influence of Na2SO4 as one of the components such the waste on thermal properties and crystallization ability of iron phosphate waste glass was studied. It was observed that Na2SO4 decreases transformation temperature and increases ΔC p. The glass characteristic temperatures, glass crystallization ability, and crystallizing phases were determined. Na2SO4 increases the glass crystallization ability which could be related with ΔC p heat capacity accompanying glass transition changes. The glass internal structure rebuilding, accompanying the sodium content increase, is considered. It is shown that ΔC p is a suitable, structure-sensitive glass crystallization ability, parameter.