CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Kui Liu,Kuibao Zhang,Ting Deng,Jianjun Zeng,Baozhu Luo,Haibin Zhang
Gd 2 Zr 2 O 7 ceramic is considered as one of the most promising host minerals for the immobilization of high-level radioactive wastes . Here, the effects of grain size on the aqueous durability of Gd 2 Zr 2 O 7 ceramics were studied. Two kinds of leaching experiments were used to research Gd 2 Zr 2 O 7 ceramic powders and bulks with different grain sizes (5 nm, 78 nm, 1 μm and 18 μm). The results demonstrate that the normalized leaching rates decrease with the increase of grain size. Through characterization and analysis, it is concluded that the hydrolysis reactions of Gd 2 Zr 2 O 7 occur in the leaching experiment and the hydrolysates are Gd(OH) 3 and Zr(OH) 4 . Besides, all the samples after leaching exhibit slight lattice contraction, which decreases with the increase of crystal grain size. The influence of leaching on the elemental distribution is most significant for the sample with grain size of 5 nm. This study has theoretical guiding significance for the application of Gd 2 Zr 2 O 7 immobilization.
研究领域:
材料科学
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核废料管理
·
环境化学
✓ 已验证
DOI
高影响因子
Materials Research Express
·
2019
·Vol. 6
·期 5
·056547
·
IF 1.449
Yinqun Hua,Bochen Jiang,Ruifang Chen,Jiangdong Cao,Wenwen Shuai,Ruitao Li
In this study, Gd2Zr2O7 -X TiSi2 (X = 0, 2.5, 5 and 7.5 wt% TiSi2) ceramics were synthesized by solid state reaction method at 1550 °C for 12 h in air. The influences of TiSi2 content on the phase, microstructure, thermophysical properties, hardness and fracture toughness were investigated. Gd2Zr2O7- X TiSi2 (X = 7.5 wt%) ceramic mainly consists of a defect fluorite phase; while Gd2Zr2O7 -X TiSi2 (X = 0, 2.5 and 5 wt% TiSi2) ceramics have an ordered pyrochlore phase. In addition, the degree of structural order decreased with the increasing TiSi2 content. The microstructure of the doped ceramic materials exhibited grain refinement. The doping of TiSi2 decreased the thermal conductivity while improved the thermal expansion coefficient, the hardness and the fracture toughness enhanced significantly. With these improved properties, the TiSi2 doped Gd2Zr2O7 ceramic materials can be a very promising material for ceramic layers of thermal barrier coating.
研究领域:
材料科学
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热障涂层研究
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
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2018
·
IF 3.794
Lan Wang,Xiaoyan Shu,Facheng Yi,Dadong Shao,Kuibao Zhang,Haibin Zhang,Xirui Lu
A series of Nd and Ce co-doped Gd 2- x Nd x Zr 2- y Ce y O 7 (0.0 ≤ x , y ≤ 2.0) ceramics were rapidly fabricated through spark plasma sintering (SPS) within 3 min. The effects of Nd and Ce contents on the phase composition, lattice parameter , active modes, microtopography and microstructure have been investigated in detail. XRD studies reveal that the compositions corresponding to 0.0 ≤ y ≤ 1.0 show a single phase and beyond 1.0 exhibit multiphase. The lattice parameters increase with elevated Nd and Ce content. The grains are densely packed on each other with cube-like shape, and the elements are almost homogeneously distributed in the compound. This synthetic method provides a simple pathway for the preparation of highly densified single phase ceramic at 1600–1700 ℃ for 3 min under pressure of 80 MPa.
研究领域:
材料科学
·
无机化学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2015
·
IF 2.605
Xirui Lu,Long Fan,Xiaoyan Shu,Sijin Su,Yi Ding,Facheng Yi
(Gd 1− x Nd x ) 2 (Zr 1− x Ce x ) 2 O 7 (0≤ x ≤1.0) ceramics were synthesized to investigate the co-doping effects on the phase evolution and chemical durability of Gd 2 Zr 2 O 7 based nuclear waste forms. The phase structures of these solid solutions were identified by X-ray diffraction and their chemical durability was evaluated by static leach test (Materials Characterization Center, MCC-1). The results show that the Gd 2 Zr 2 O 7 ceramic adopts a pyrochlore structure while the co-doped (Gd 1− x Nd x ) 2 (Zr 1− x Ce x ) 2 O 7 (0.2≤ x ≤1.0) compositions exhibit a defect fluorite structure. Moreover, the normalized release rates of each element in (Gd 1− x Nd x ) 2 (Zr 1− x Ce x ) 2 O 7 (0≤ x ≤1.0) waste forms increase with the growing temperature and converge to constant values with enhanced leaching time. In the discussed time range (42 days), all the considered elements show a normalized release rate lower than 10 −4 g m −2 d −1 . Gd shows the highest normalized release rate of all the involved elements, while Zr shows the best chemical durability.
研究领域:
材料科学
·
核能工程
✓ 已验证
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2019
·
IF 4.029
Weiwei Li,Kuibao Zhang,Dayan Xie,Ting Deng,Baozhu Luo,Haibin Zhang,Xuegang Huang
Highly transparent Gd 2 Zr 2 O 7 ceramic was fabricated by vacuum sintering using combustion synthesized nanopowder with mean particle size of about 80 nm. The morphology and structure were analyzed by X-ray diffractometer, scanning electron microscopy, Raman spectroscopy and transmission electronic microscopy . The Gd 2 Zr 2 O 7 nanopowder and transparent ceramic are both in low ordered pyrochlore structure. The effects of sintering temperature on the density and transmittance of Gd 2 Zr 2 O 7 ceramic were investigated, and the optimum sintering temperature (1825 °C) was obtained. Gd 2 Zr 2 O 7 transparent ceramic sintered at 1825 °C for 6 h shows the highest transmittance of 77.3 % and the average grain size of about 80 μm.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2020
·
IF 4.495
Zhangyi Huang,Qiuyao Li,Yutong Zhang,Junjing Duan,Haomin Wang,Zhe Tang,Yao Yang,Jianqi Qi,Tiecheng Lu
A nitrate–citrate combustion method combined with microwave sintering was firstly employed for the rapid fabrication of the Gd 2 Zr 2 O 7 matrix immobilizing various amounts of simulated nuclear wastes . Phase evolutions, microstructure changes, element distributions, densification processes and mechanical properties of the as-prepared (1 – x )Gd 2 Zr 2 O 7 · x TRPO (0.0 ≤ x ≤ 0.6) at various temperatures were investigated. Compared to the reported studies, we have increased the immobilization amount of simulated TRPO waste within a crystal structure from 45 to 60 wt%. T d and T g (the threshold temperatures to trigger accelerated densification and grain growth, respectively) were employed to divide the densification process into three stages. the mechanical properties and the densification stages of the (1 – x )Gd 2 Zr 2 O 7 · x TRPO (0.0 ≤ x ≤ 0.6) ceramics sintered under microwave sintering at various temperatures were finally determined. Fine-grained (1 – x )Gd 2 Zr 2 O 7 · x TRPO (0.0 ≤ x ≤ 0.6) ceramic waste forms with average grain size less than 200 nm and relative density higher than 90% can be obtained by microwave sintering at sintering temperature less than 1400 °C.
研究领域:
材料科学
·
核废料管理
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Zhangyi Huang,Wanying Guo,Yang Shi,Ruichong Chen,Zhijun Wang,Yutong Zhang,Junjing Duan,Jianqi Qi,Haomin Wang
The Gd 2 Zr 2 O 7 (GZO)-based ceramic waste form exhibits promising potential for radioactive waste immobilization. However, the isomorphic immobilization capacity and irradiation effects of GZO-based ceramic waste forms with varying waste loads remain inadequately understood. This study employed a facile combustion method to synthesize ceramic powders and utilized conventional sintering with a relatively short dwelling time to fabricate GZO-based ceramic waste forms. We investigated the isomorphic immobilization behavior and He ion irradiation effects of the synthesized waste forms. The outcomes demonstrate that GZO effectively immobilizes simulated waste composed of 11 types of oxides, achieving a waste load as high as 50 wt% with a single pyrochlore phase and homogeneous element distribution. Under He + irradiation, aggravated structural degradations, including exacerbated lattice swelling, increased amorphization degree, and premature He bubble chain/microcrack formation, were observed in GZO-based waste forms with an increasing waste load.
研究领域:
材料科学
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核能工程
·
放射化学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Haomin Wang,Yang Shi,Mao Deng,Zhangyi Huang
High-pressure sintering (HPS) is a promising technique for producing nanocrystalline ceramics with unique properties. However, the densification mechanisms of HPS for nanocrystalline ceramics at different sintering stages remain controversial. This study focuses on Gd 2 Zr 2 O 7 (GZO) nanocrystalline ceramics, investigating their microstructure evolution and densification behavior under varying pressures, temperatures, and dwelling times. The HPS process involves distinct stages: cold compaction, hot compaction, and isothermal progression. During cold compaction, densification is driven by the breakdown of aggregates, particle rearrangement, and local plastic deformation , resulting in a relative density of 84.8 %. The intermediate stage achieves an increase to ∼93.7 % in relative density by grain boundary-mediated plastic deformation mechanism . The final isothermal stage, held at 500 °C/5 GPa, achieves nearly full density (∼99.2 %) through diffusion creep , eliminating microstructural defects. This comprehensive understanding of HPS densification mechanisms, exemplified by GZO ceramics, contributes to advancing nanocrystalline ceramic applications .
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Guilin Wei,Xiaoyan Shu,Mingfen Wen,Yuexiang Lu,Tao Duan,Shunzhang Chen,Hexi Tang,Jing Chen,Faqin Dong,Yi Xie,Yang He,Xirui Lu
Nuclear waste generated from the nuclear industry should be safely treated because of its harmful effects on the environment and humans. In this study, the mechanism of the as-prepared Gd 2 Zr 2 O 7 for nuclear waste immobilization was investigated as an example in the simulation of waste immobilization under spark plasma sintering (SPS) conditions. The solid solubility limit of the waste in the sintered matrices was 45 mol% at 1725 °C and 1800 °C. The phase transformation from fluorite to pyrochlore could be detected owing to the increase in the ionic radius ratio when the waste was immobilized in the matrix structure. A high sintering temperature promotes transformation by increasing the orderliness of the matrix structure and destroying the crystalline structures to form an amorphous structure, results in a decrease in structural orderliness. Moreover, the leaching rates of Nd, at approximately 3.5 × 10 −8 g·m −2 ·d −1 at 42 d, demonstrated high chemical stability in the matrices doping with 45 mol% simulated nuclear waste. A mechanism is proposed in this study for treating radioactive waste using Gd 2 Zr 2 O 7 ceramic under SPS conditions.
研究领域:
材料科学
·
环境科学
·
核能工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）