YIG陶瓷对三价锕系模拟核素的固化行为研究  

Immobilizing Behavior of Trivalent Actinide Nuclides by YIG Ceramics

作　　者：罗世淋 张胜泰 许保亮[1] 王凌坤 段思逸菡 丁艺[1] 赵倩 段涛[1] LUO Shilin;ZHANG Shengtai;XU Baoliang;WANG Lingkun;DUAN Siyihan;DING Yi;ZHAO Qian;DUAN Tao(National Co-Innovation Center for Nuclear Waste Disposal and Environmental Safety,Southwest University of Science and Technology,Mianyang 621010,China;Physics and Space Sciences College,China West Normal University,Nanchong 637002,China)

机构地区：[1]西南科技大学核废物与环境安全省部共建协同创新中心,绵阳621010 [2]西华师范大学物理与空间科学学院,南充637002

出　　处：《无机材料学报》2022年第7期757-763,共7页Journal of Inorganic Materials

基　　金：国家重点研发计划(2016YFC1402500);国家自然科学基金(41272050,21976148)。

摘　　要：石榴石具有较大的锕系包容量及化学灵活性,被认为是潜在的锕系核素固化基材。本工作以Nd^(3+)模拟三价锕系核素,通过高温固相法成功合成了Y_(3–x)Nd_(x)Fe_(5)O_(12)(0≤x≤2)系列钇铁石榴石(YIG)固化体。研究了Nd在YIG固化体中的固溶极限和Nd掺杂量对固化体的物相和微观结构的影响规律,以及不同pH条件下Nd掺杂钇铁石榴石固化体的化学耐久性。研究结果表明,当x≤1.7时,YIG基固化体为纯相YIG;当x≥1.8时,YIG基固化体中YIG、NdFeO_(3)和Fe_(2)O_(3)三相共存。纯相YIG基固化体对Nd^(3+)的固溶极限约为29.5%(质量分数)。随着Nd掺杂量增加,固化体的密度增大,体积减小,孔隙率减小。浸出实验结果显示,28 d后元素归一化浸出率(LR_(i))逐渐趋于平衡,42 d后,其元素的LR_(i)为10^(-6)~10^(–5) g·m^(-2)·d^(–1)。LR_(Y)小于LR_(Nd),且酸性溶液中元素归一化浸出率也略高于中性和碱性溶液。这些结果表明,YIG陶瓷是理想的三价锕系核素候选固化基材。Garnet is considered as a potential matrix for immobilizing high-level radioactive waste(HLW)because of its large actinide package capacity and chemical flexibility.Y_(3-x)Nd_(x)Fe_(5)O_(12)(0≤x≤2)series yttrium iron garnet(YIG)samples was successfully synthesized by solid-state sintering method using Nd^(3+)to simulate trivalent actinides.The solubility limit of Nd in the YIG and the influence of Nd doping amount on the phase and microstructure of ceramics was studied.Then the chemical durability of Nd-doped yttrium iron garnet solidified body under different pH conditions was evaluated.The results show that the ceramics with x≤1.7 show homogeneous single YIG,but the ceramics with x≥1.8 exhibit coexistence of three crystal phases(YIG,NdFeO_(3) and Fe_(2)O_(3)).The solubility limit of Nd^(3+)in the pure YIG is about 29.5%(in mass).As the amount of Nd doping increases,the density of the ceramics increases,the volume decreases,and the porosity decreases.The leaching experiment results show that the normalized leaching rate of the elements(LRi)is 10^(-6)~10^(-5)g·m^(-2)·d^(-1).LRY is smaller than LRNd,and the normalized leaching rate of the elements in acid leachate is slightly higher than those in neutral and alkaline leachates.The results indicate that YIG ceramics are a potential candidate form for trivalent actinides.

关 键 词：钇铁石榴石(YIG) 锕系核素 相演变 化学稳定性 

分 类 号：TQ174[化学工程—陶瓷工业]