Crystal structure design and chemical stability of radionuclides immobilized on high-entropy garnet ceramics

High-entropy (HE) wasteforms has attracted extensive attention because of its low solubility and the ability to immobilize a variety of nuclides. The atomic size difference (δ) is a necessary condition for designing HE garnet wasteforms (8.29 % ≤ δ ≤ 11.28 %). The leaching experiment shows that the leaching rate of simulated nuclides in the prepared HE garnet wasteforms is about 10-7–10-9 g m-2 · d-1, which is far lower than that of traditional garnet (10-5–10-6 g m-2 · d-1). The dissolution of HE garnet wasteforms cations into the leaching solution is carried out through internal diffusion. The extremely low leaching rate is mainly due to lattice distortion requires greater energy for the movement of cationic in the lattice. This work indicates that HE garnet wasteforms are a noteworthy substrate for immobilizing nuclides.