Kexin Lv,Hengcheng Wan,Yi Li,Shengtai Zhang,Qiang He
The garnet structure Y 3 Fe 5 O 12 (YIG) possesses a high immobilization capacity for actinides. However, the related research on the sensitivity of garnet structures to irradiation damage is still in its infancy. Herein, we synthesize Y 3-x Nd x Fe 5 O 12 (x = 0.1, 1.8) ceramics and irradiate them with 2 MeV α-particle irradiation to fluences ranging from 1 × 10 14 to 1 × 10 17 ions/cm 2 at room temperature. We evaluated the effects of irradiation damage on the phase transition and chemical stability. An amorphous layer with a thickness of 84 nm is formed by irradiation, though the grain shape and element distribution remain uniform after irradiation. In addition, Y 3-x Nd x Fe 5 O 12 (x = 0.1, 1.8) ceramics exhibit excellent chemical stability (∼ 10 −5 g m −2 · d −1 ) in the leaching process. Restricted by the topological structure of garnet, the increase in solid solubility does not lead to a change in the radiation tolerance of the garnet structure, which means that garnet of different compositions should have similar and predictable radiation tolerance.
The garnet structure is a promising solid material for nuclear waste because it can contain all kinds of actinides. Yttrium iron garnet Y 3 Fe 5 O 12 (YIG) is the model component of this kind of substitute. In this study, Nd-doped YIG ceramic samples were prepared by microwave sintering at different sintering temperatures (1100 °C, 1200 °C, and 1300 °C) for different sintering time (0.5 h, 2 h, 4 h, and 6 h). The effects of synthesis temperature and sintering time on the solubility and microstructure of Y 3-x Nd x Fe 5 O 12 (0 ≤ x ≤ 3.0) were evaluated. The X-ray diffraction (XRD), scanning electron microscopy (SEM) and backscattering scanning electron microscopy (EBSD) results show that single phase garnet structure can be synthesized and enhanced solubility of Nd in YIG was found at higher temperatures. The solubility of Nd in garnet is 50 mol% (x = 1.5) and 60 mol% (x = 1.8) at 1200 °C and 1300 °C, respectively. There is no significant dependence of the solubility on sintering time. The SEM analysis and Archimedes drainage test show that the relative density of Y 1.2 Nd 1.8 Fe 5 O 12 ceramics is 88.15% and 99.94% at 0.5 h and 6 h, respectively, indicating dense YIG could be obtained with a relatively long sintering time. The results show that microwave sintering can rapidly and efficiently synthesize the YIG ceramic samples.
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