In-situ observation of irradiation-induced amorphization on fluorapatites doped with REEs (REE = La, Nd, Sm, Tb, Er, and Lu) of various ionic radii

IF 2.8 2区工程技术 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Nuclear Materials Pub Date : 2024-09-26 DOI:10.1016/j.jnucmat.2024.155425

Xiaotian Hu, Shengming Jiang, Jiemin Zhu, Jian Zhang

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引用次数: 0

Abstract

The immobilization of nuclear waste containing various actinides requires the actinide host phases to maintain long-term stability under alpha decay damage. In this study, the irradiation resistance to amorphization of fluorapatite compounds with the formula of Ca₉REE(PO₄)₅(SiO₄)F₂ (REE: rare earth element, REE = La, Nd, Sm, Tb, Er, and Lu) were investigated, where REEs³⁺ with decreased ionic radii were used to simulate actinides in immobilization wastes. In-situ 800 keV Kr²⁺ irradiation was performed with varying temperatures. The critical amorphization temperature,

T_{c}

, for these apatites were found to be 513.8, 503.7, 494.1, 493.7, 483.1 and 460.9 K, respectively.

T_{c}

shows a distinct decreasing trend with the decrease of ionic radii of doped REEs³⁺, indicating enhanced irradiation resistance. The selected REEs exhibited increasing electronegativity, which correlated with an increase in bonding ionic properties. This trend is unfavourable for the formation of a covalent network, thereby enhancing irradiation resistance. Besides, the decreased ionic radii of doped REEs³⁺ enhanced the migration and diffusion rates of smaller REE³⁺ after the collision cascade process. Additionally, the dopant REEs³⁺ showed a significant preference for CaⅡ sites. This preference decreased as the ionic radius of doped REE³⁺ and reduced the average ionic radius of CaⅠ sites. Consequently, the one-dimensional channel in apatite became larger, facilitating the rearrangement of F⁻ ion. This study investigated the irradiation-induced amorphization of REE-silicon doped fluorapatites and the results highlighted the importance of composition of immobilization materials on irradiation performance.

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原位观测掺杂不同离子半径 REE（REE = La、Nd、Sm、Tb、Er 和 Lu）的氟磷灰石的辐照诱导非晶化现象

固定含有各种锕系元素的核废料需要锕系元素主相在α衰变破坏下保持长期稳定性。在这项研究中，研究了公式为 Ca9REE(PO4)5(SiO4)F2（REE：稀土元素，REE = La、Nd、Sm、Tb、Er 和 Lu）的氟磷灰石化合物的抗辐照变质能力，其中使用了离子半径减小的 REEs3+ 来模拟固定化废物中的锕系元素。在不同温度下进行了 800 keV Kr2+ 原位辐照。发现这些磷灰石的临界变质温度 Tc 分别为 513.8、503.7、494.1、493.7、483.1 和 460.9 K。随着掺杂的 REEs3+ 离子半径的减小，Tc 呈明显的下降趋势，表明抗辐照能力增强。所选 REEs 的电负性不断增加，这与成键离子特性的增加有关。这种趋势不利于共价网络的形成，从而增强了抗辐照能力。此外，掺杂 REEs3+ 的离子半径减小，提高了碰撞级联过程后较小 REE3+ 的迁移和扩散速率。此外，掺杂的 REEs3+ 对 CaⅡ 位点有明显的偏好。这种偏好随着掺杂 REE3+ 离子半径的增大而减小，并降低了 CaⅠ 位点的平均离子半径。因此，磷灰石中的一维通道变大，有利于 F 离子的重排。本研究探讨了辐照诱导的掺杂 REE-硅的氟磷灰石的非晶化过程，结果凸显了固定化材料的组成对辐照性能的重要性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Nuclear Materials 工程技术-材料科学：综合

CiteScore

5.70

自引率

25.80%

发文量

601

审稿时长

63 days

期刊介绍： The Journal of Nuclear Materials publishes high quality papers in materials research for nuclear applications, primarily fission reactors, fusion reactors, and similar environments including radiation areas of charged particle accelerators. Both original research and critical review papers covering experimental, theoretical, and computational aspects of either fundamental or applied nature are welcome. The breadth of the field is such that a wide range of processes and properties in the field of materials science and engineering is of interest to the readership, spanning atom-scale processes, microstructures, thermodynamics, mechanical properties, physical properties, and corrosion, for example. Topics covered by JNM Fission reactor materials, including fuels, cladding, core structures, pressure vessels, coolant interactions with materials, moderator and control components, fission product behavior. Materials aspects of the entire fuel cycle. Materials aspects of the actinides and their compounds. Performance of nuclear waste materials; materials aspects of the immobilization of wastes. Fusion reactor materials, including first walls, blankets, insulators and magnets. Neutron and charged particle radiation effects in materials, including defects, transmutations, microstructures, phase changes and macroscopic properties. Interaction of plasmas, ion beams, electron beams and electromagnetic radiation with materials relevant to nuclear systems.