Phase evolution, solubility and substitution behavior of CaZrTi2O7-Ho2Ti2O7 ceramics for potential nuclear waste immobilization

被引：0

作者：

Ji, Xiuhua ^{[1
,2
]}

Song, Yanhao ^{[1
,2
]}

Wang, Jiarun ^{[2
]}

Ding, Yi ^{[2
]}

Ji, Shiyin ^{[1
,2
,3
]}

Duan, Tao ^{[1
,3
,4
]}

机构：

[1] Southwest Univ Sci & Technol, Tianfu Inst Res & Innovat, Chengdu 610299, Peoples R China

[2] Southwest Univ Sci & Technol, Sch Natl Def Sci & Technol, Mianyang 621010, Peoples R China

[3] Southwest Univ Sci & Technol, Natl Coinnovat Ctr Nucl Waste Disposal & Environm, Mianyang 621010, Peoples R China

[4] Southwest Univ Sci & Technol, State Key Lab Environm Friendly Energy Mat, Mianyang 621010, Peoples R China

来源：

CERAMICS INTERNATIONAL | 2024年 / 50卷 / 24期

基金：

中国国家自然科学基金;

关键词：

Zirconolite; Pyrochlore; Substitution mechanism; Phase evolution; Minor actinides; GLASS-CERAMICS; RARE-EARTH; ZIRCONOLITE; GD; ND; CRYSTALLIZATION; MICROSTRUCTURE; A(2)B(2)O(7); DIFFRACTION; SYSTEM;

D O I：

10.1016/j.ceramint.2024.10.392

中图分类号：

TQ174 [陶瓷工业]; TB3 [工程材料学];

学科分类号：

0805 ; 080502 ;

摘要：

Zirconolite and pyrochlore have been considered as the potential immobilization matrix materials of minor actinides due to their high solubility, radiation tolerance and chemical durability. In this work, a series of xHo2xZr1-xTi2O7 (0.1 <= x <= 1.0) ceramics were prepared by solid state synthesis and sintering at 1400 degrees C for twice. Powder X-ray Diffraction (XRD), Backscattered Scanning Electron Microscopy with Energy-Dispersive ray spectroscopy (BSEM-EDX), Transmission Electron Microscopy (TEM) were employed to investigate the phase evolution, solubility, and substitution mechanism of Ho. The results displayed that zirconolite-2M would transformed to zirconolite-4M and then to pyrochlore with increasing Ho concentration. The initial phase transformation of zirconolite-2M to zirconolite-4M, subsequently zirconolite-4M to pyrochlore were observed x = 0.2 and 0.4 samples, respectively. Zirconolite-4M could be synthesised at x = 0.38 sample with trace perovskite. Moreover, the semi-quantitively solubility limits of Ho in zirconolite-2M and zirconolite-4M were determined to be 27 and 41.5 at.%, respectively. Single-phase pyrochlore were fabricated after 70 at.%. addition, the novel substitution mechanism was revealed by Rietveld refinement with Ho preferentially replacing the Ca of zirconolite-2M so that some replaced Ca occupied vacant Zr site. For pyrochlore, Ho, Ca and occupied A site (16d) and Ti entered in B site (16c). The findings would provide more insights into zirconolite-pyrochlore ceramic system.

引用

页码：55342 / 55350

页数：9

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