Crystallization behavior of boron in low-temperature immobilization of iodine waste

The immobilization of iodine waste is a challenge in the field of nuclear waste. In this work, iodine waste (silver-coated silica gel with different iodine loadings) was immobilized at low-sintering temperatures (500, 550, and 600 ​°C). XRD represented that the crystallized phases of the sintered matrix consist of AgI and B2O3. The crystallization behavior of boron can be found as the sintering temperature increased from 500 ​°C to 600 ​°C. FT-IR results proved that in the process of crystallization, part of the microstructure related to B–O stretching transformed from [BO4] to [BO3] units, which benefits low-temperature iodine waste immobilization due to the bonding energy of [BO3] is higher than that of [BO4]. Our work reveals the B-related microstructure transition in low-temperature immobilization iodine waste.