Synthesis and irradiation behavior of (Gd0.2Sm0.2Dy0.2Er0.2Yb0.2)2Ti2O7 high-entropy pyrochlore waste forms consolidated by spark plasma sintering

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum Pub Date : 2024-11-28 DOI:10.1016/j.vacuum.2024.113893

Xiaoyu Ji , Penghui Lei , Jiahao Chen , Jie Qiu , Qing Peng , Di Yun

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引用次数: 0

Abstract

The development of spent fuel reprocessing, which generates large amounts of high-level waste, necessitates effective management of waste containing radioactive elements. Pyrochlore (A₂B₂O₇) is considered one of the most promising immobilized matrixes for high-level waste due to its excellent physicochemical stability and irradiation resistance. A novel kind of high-entropy pyrochlore ceramic (Gd_0.2Sm_0.2Dy_0.2Er_0.2Yb_0.2)₂Ti₂O₇, as an improved waste form matrix, was successfully synthesized using spark plasma sintering in this work. The mechanical properties, physical density, and microstructure of the densified pellets have been investigated in relation to different sintering temperatures (ranging from 1000 °C to 1400 °C). A single-component pyrochlore phase high-entropy ceramic was densified at 1300 °C, achieving a maximum hardness of 12.68 GPa and a density of 97.64 %. The irradiation tolerance of high-entropy pyrochlore was assessed by ion irradiation of 400 keV He⁺ with 10 × 10¹⁷ ions/cm² at room temperature (RT). Ion irradiation can induce the transformation of the pyrochlore superlattice of (Gd_0.2Sm_0.2Dy_0.2Er_0.2Yb_0.2)₂Ti₂O₇ into a fluorite sublattice. Compared to Gd₂Ti₂O₇, (Gd_0.2Sm_0.2Dy_0.2Er_0.2Yb_0.2)₂Ti₂O₇ exhibits significantly reduced irradiation damage with suppressed generation and coalescence of helium bubbles due to chemical disorder and lattice distortion. High-entropy pyrochlore (Gd_0.2Sm_0.2Dy_0.2Er_0.2Yb_0.2)₂Ti₂O₇ exhibits superior mechanical properties and irradiation resistance, suggesting its application as a promising immobilization matrix for nuclear waste.

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来源期刊

Vacuum 工程技术-材料科学：综合

CiteScore

6.80

自引率

17.50%

发文量

审稿时长

34 days

期刊介绍： Vacuum is an international rapid publications journal with a focus on short communication. All papers are peer-reviewed, with the review process for short communication geared towards very fast turnaround times. The journal also published full research papers, thematic issues and selected papers from leading conferences. A report in Vacuum should represent a major advance in an area that involves a controlled environment at pressures of one atmosphere or below. The scope of the journal includes: 1. Vacuum; original developments in vacuum pumping and instrumentation, vacuum measurement, vacuum gas dynamics, gas-surface interactions, surface treatment for UHV applications and low outgassing, vacuum melting, sintering, and vacuum metrology. Technology and solutions for large-scale facilities (e.g., particle accelerators and fusion devices). New instrumentation ( e.g., detectors and electron microscopes). 2. Plasma science; advances in PVD, CVD, plasma-assisted CVD, ion sources, deposition processes and analysis. 3. Surface science; surface engineering, surface chemistry, surface analysis, crystal growth, ion-surface interactions and etching, nanometer-scale processing, surface modification. 4. Materials science; novel functional or structural materials. Metals, ceramics, and polymers. Experiments, simulations, and modelling for understanding structure-property relationships. Thin films and coatings. Nanostructures and ion implantation.