Influences of SrO on the structure, thermo-physical and chemical properties of zinc iron borophosphate glasses as host matrices for radioactive waste

Abstract

The structures, thermo-physical, and chemical properties of the glass series 40 P2O5-10 B2O3-20Fe2O3-(30-X) ZnO-X SrO with X = 0–30 mol% were investigated. X-ray diffraction experiments confirmed the amorphous structure of the prepared glasses. Fourier-transform infrared spectroscopy FTIR was used to examine the structural changes as the glass formulations evolved. FTIR results indicated that the phosphate chain increases as the SrO content rises. The differential thermal analysis DTA was used to measure and discuss the thermal stability properties of the synthesized glasses. The DTA data indicated that the network of the prepared glasses is most unstable at 30 mol% of SrO. As strontium is substituted for zinc, a systematic increase in density (ρ), glass transition temperature (Tg), and thermal expansion coefficient (α), but the molar volume (Vm) of the glasses was decreased. The (α) of the synthesized glasses are diverse from 55 × 10−7 to 87× 10−7 C−1 over the temperature range (24–400°C). The chemical stability of the prepared amorphous materials was determined from their dissolution rate in deionized water at 90°C. The chemical stability of the glasses improves as the SrO content increases. The glasses obtained have a strong aqueous durability (10−7-10−8 g cm−2 min−1) after 14 days immersion. The results show that the prepared strontium zinc iron boro-phosphate glasses may be strong and effective material used as host matrices for radioactive waste containing high content of strontium.