熔盐法低温合成掺钕ZrSiO_(4)陶瓷的物相演变和化学稳定性  

Nd-doped ZrSiO_(4)Ceramics:Synthesis in Molten Salt at Low Temperature,Phase Evolution and Chemical Stability

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作  者:刘建[1,2] 王凌坤 许保亮 赵倩[1,2] 王耀萱 丁艺 张胜泰 段涛[1,2] LIU Jian;WANG Lingkun;XU Baoliang;ZHAO Qian;WANG Yaoxuan;DING Yi;ZHANG Shengtai;DUAN Tao(National Co-Innovation Center for Nuclear Waste Disposal and Environmental Safety,Southwest University of Science and Technology,Mianyang 621010,China;State Key Laboratory of Environment-friendly Energy Materials,School of National Defence Science&Technology,Southwest University of Science and Technology,Mianyang 621010,China;Innovation Research Team for Advanced Ceramics,Institute of Nuclear Physics and Chemistry,China Academy of Engineering Physics,Mianyang 621900,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]西南科技大学国防科技学院,环境友好能源材料国家重点实验室,绵阳621010 [3]中国工程物理研究院核物理与化学研究所高级陶瓷创新研究团队,绵阳621900

出  处:《无机材料学报》2023年第8期910-916,共7页Journal of Inorganic Materials

基  金:国家自然科学基金(U2167221,21906133,22176157);四川省科技厅四川省青年科技创新研究团队(2021JDTD0019);国防基础科学研究计划(JCKY2019404D001)。

摘  要:相较于传统固相烧结方法,熔盐在较低的温度下提供了快速的传质和成核过程,可合成用于固化高放废物(HLW)的陶瓷固化体。本工作采用熔盐法(MSS)在不同烧结温度(1100、1200、1300、1400、1500℃)和不同烧结时间(3、6、9、12、15 h)下制备了掺Nd的锆石(ZrSiO_(4))陶瓷(Zr_(1-x)Nd_(x)SiO_(4-x/2)(0≤x≤0.1)),并采用静态浸出试验(PCT)研究掺Nd的ZrSiO_(4)陶瓷在模拟地质处置环境下的化学稳定性。在熔盐与氧化物最佳摩尔比为10:1、烧结温度为1200℃、烧结时间为6 h的较温和条件下,利用熔盐法成功合成了Zr_(1–x)Nd_(x)SiO_(4–x/2),可将Nd在ZrSiO_(4)中的固溶摩尔分数提高到8%,结果显示MSS法能够降低陶瓷合成温度,缩短合成时间,提高固溶量。ZrSiO_(4)陶瓷对三价锕系核素的固化机理为晶格固化。浸出实验结果显示,Nd的归一化浸出率(LRNd)低至~10–5 g·m^(–2)·d^(–1)。浸出前后ZrSiO_(4)陶瓷未发生物相演变,展现出较好的结构稳定性。浸出模型显示Nd浸出归因于陶瓷表面层发生溶解。研究结果表明,MSS法是一种高效的合成陶瓷固化体的手段。In contrast to conventional solid-phase sintering,molten salt method can provide a fast mass transfer and nucleation process at lower temperatures which has potential to synthesize the ceramic solid solution for immobilization of high-level nuclear waste(HLW).In this work,Nd-doped zircon(ZrSiO_(4))ceramics(Zr_(1-x)Nd_(x)SiO_(4-x/2)(0≤x≤0.1))were prepared by the molten salt synthesis(MSS)at different sintering temperatures(1100,1200,1300,1400,1500℃)for different sintering time(3,6,9,12,and 15 h).Chemical stability of Nd-doped zircon ceramics in simulated geological disposal environment was studied by static leaching test(PCT).Zr_(1-x)Nd_(x)SiO_(4-x/2)was synthesized by the molten salt method under the optimum molar ratio of molten salt to oxide at 10:1,sintering temperature at 1200℃and sintering time of 6 h with the solid solution of Nd in ZrSiO_(4)being increased to 8%(in mol).The MSS can reduce the synthetic temperature,shorten the sintering time and save the solid solution.The immobilizing mechanism of ZrSiO_(4)ceramics for trivalent actinide nuclides is lattice immobilizing.Experimental results show that the normalized leaching rate(LRNd)of Nd is as low as~10–5 g·m^(–2)·d^(–1).ZrSiO_(4)ceramics have no phase evolution before and after leaching,suggesting good structural stability.TLeaching model consolidates that Nd leaching is due to dissolution of the ceramic surface layer.Data from this study show that MSS is a promising method to synthesize ceramics solid solution.

关 键 词:固化 锆石 熔盐 化学稳定性 

分 类 号:TQ174[化学工程—陶瓷工业]

 

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