Synthesis, microstructures, and aqueous chemical durability of high-entropy pyrochlore ceramic Eu2B2O7 (BTi, Zr, Sn, Hf, Nb, and Ce) for nuclear waste immobilization

IF 6.2 2区材料科学 Q1 MATERIALS SCIENCE, CERAMICS

Journal of The European Ceramic Society Pub Date : 2025-09-23 DOI:10.1016/j.jeurceramsoc.2025.117844

Zhuangzhuang Ma , Yunhao Wang , Tianhao Rui , Yulin Lan , Linyuan Lu , Yang Yu , Mingxuan Deng , Tianxing Lan , Zhekang Zhao , Zhen Teng , Haibin Zhang

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引用次数: 0

Abstract

High-entropy pyrochlore ceramics with the nominal composition Eu₂B₂O₇, incorporating up to five equiatomic B-site cations, were synthesized via a solid-state reaction method and evaluated their aqueous chemical durability for nuclear waste immobilization. Comprehensive characterization using XRD, Raman, and SEM analyses confirmed the formation of a single-phase pyrochlore structure with uniform and random elemental distribution. However, secondary phases were observed in the Ce- and Nb-doped samples, which is attributed to the larger ionic radius of Ce and the higher valence state of Nb. The 42 days leaching tests revealed normalized element release rates ranging from 10⁻⁵ to 10⁻⁷ g/(m²∙d), significantly lower than those of conventional pyrochlore materials. This enhanced durability is attributed to synergistic effects of electronegativity, ionic radius, and atomic number, which together hinder cation diffusion and strengthen chemical durability at the B site. These findings demonstrate the potential of Eu₂B₂O₇ high-entropy pyrochlore ceramics as long-term host materials for high-level radioactive waste. This study provides a valuable resource for enriching the thermophysical properties database of B-site high-entropy pyrochlore solidification, thereby supporting their engineering development.

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用于核废料固定化的高熵焦绿陶瓷Eu2B2O7 （BTi, Zr, Sn, Hf， Nb和Ce）的合成、微观结构和水化学耐久性

采用固相反应方法合成了标称成分为Eu2B2O7的高熵焦绿石陶瓷，其中含有多达5个等原子b位阳离子，并评估了其用于核废料固定化的水化学耐久性。通过XRD、Raman、SEM等综合表征，证实形成了元素分布均匀随机的单相焦绿石结构。然而，在Ce和Nb掺杂的样品中观察到二次相，这是由于Ce的离子半径更大，Nb的价态更高。42天的浸出试验显示，标准化元素释放率为10−5 ~ 10−7 g/(m2∙d)，显著低于常规焦绿盐材料。这种增强的耐久性归因于电负性、离子半径和原子序数的协同作用，它们共同阻碍了阳离子的扩散，增强了B位点的化学耐久性。这些发现证明了Eu2B2O7高熵焦绿石陶瓷作为高放射性废物长期寄主材料的潜力。本研究为丰富b位高熵焦绿石凝固热物性数据库提供了宝贵的资源，从而支持其工程开发。

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 The European Ceramic Society 工程技术-材料科学：硅酸盐

CiteScore

10.70

自引率

12.30%

发文量

863

审稿时长

35 days

期刊介绍： The Journal of the European Ceramic Society publishes the results of original research and reviews relating to ceramic materials. Papers of either an experimental or theoretical character will be welcomed on a fully international basis. The emphasis is on novel generic science concerning the relationships between processing, microstructure and properties of polycrystalline ceramics consolidated at high temperature. Papers may relate to any of the conventional categories of ceramic: structural, functional, traditional or composite. The central objective is to sustain a high standard of research quality by means of appropriate reviewing procedures.