Journal of Solid State Chemistry

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 B 2 O 3 . 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 [BO 4 ] to [BO 3 ] units, which benefits low-temperature iodine waste immobilization due to the bonding energy of [BO 3 ] is higher than that of [BO 4 ]. Our work reveals the B-related microstructure transition in low-temperature immobilization iodine waste. B 2 O 3 will crystallize in the iodine waste matrix sintered at low temperatures, which will lead to the change of the microstructure. • Crystallization behavior of boron was proved by XRD results. • The crystallization behavior would affect the microstructure of the matrix. • The iodine waste was chemically and physically immobilized in the matrix.

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