CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Jingwei Chen,Xinqiang Wang
Three kinds of Gd 2 Zr 2 O 7 /ZrO 2 (GZC) composite fibers with different proportions of Gd 2 Zr 2 O 7 were prepared by electrospinning method through changing the amount of Gd 3+ in precursor solutions. The thermal decomposition, crystallization process , high temperature stability and heat-conducting properties of GZC fibers were fully characterized. The results showed that there were three crystalline phases, tetragonal phase ZrO 2 , cubic phase ZrO 2 and defect fluorite phase Gd 2 Zr 2 O 7 in all the GZC fibers. The content of Gd 2 Zr 2 O 7 increased gradually with the increase of Gd 3+ in precursor solutions which led to the gradual slowing down of grain growth rate, the decrease of thermal conductivity and the increase of high temperature stability of the obtained composite fibers. The thermal conductivities of all the GZC fiber sheets were lower than that of 7YSZ fiber sheet. The sheets of all the GZC fibers could keep the high temperature stability up to 1300 °C.
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
·
2023
·
IF 5.2
Lei Yu,Kuibao Zhang,Kui Liu,Baozhu Luo
In this study, the chemical durability of Gd 2 Zr 2 O 7 transparent ceramics was investigated under different pH environments. The influence of acidic and alkaline environments on the leaching behavior of Gd 2 Zr 2 O 7 immobilization matrix were studied to simulate the disposal of nuclear waste forms in deep geological landfills. The measured results demonstrate that the normalized leaching rates in acidic environments are higher than those in alkaline and neutral environments. The macroscopic color of all samples fades after leaching, and the visible range in-line transmittance of the leached transparent ceramics decreases slightly at pH ≤ 9. The leaching behavior leads decrement of lattice volume and increment of surface roughness, but it exhibits no significant effect on the surface elemental distribution. Never the less, Gd 2 Zr 2 O 7 transparent ceramic exhibits excellent chemical durability in weak alkaline environment, and the leaching process leads to the discoloration of Gd 2 Zr 2 O 7 transparency.
研究领域:
材料科学
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环境科学
✓ 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
·
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
CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Jingwei Chen,Xinqiang Wang,Yongshuai Xie,Shuying Shi,Guanghui Zhang,Luyi Zhu
Gd 2 Zr 2 O 7 /ZrO 2 (GZC) composite fibers were prepared by electro-spinning method. The XRD , XPS and Raman results showed that there were three crystalline phases, tetragonal phase ZrO 2 , cubic phase ZrO 2 and defect fluorite phase Gd 2 Zr 2 O 7 in GZC composite fibers. GZC fibers remained an intact fiber texture up to 1400 °C according to SEM photographs. The thermal conductivity of GZC fibers was between 0.173 W/(m·K) at 400 °C and 0.309 W/(m·K) at 800 °C, which was lower than that of 7YSZ under the same experimental conditions. The fiber sheet with density about 3.5 g/cm 3 has thermal shrinkage less than 3% at 1400 °C. Hence, GZC fibers could be used as refractories for heat protection.
研究领域:
材料科学
·
热能工程
✓ 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
CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Yao Yang,Yanli Shi,Junjing Duan,Kailei Lu,Gang Cheng,Yiding Zhao,Zhangyi Huang,Peitong Li,Nian Wei,Xinghua Zhu,Jianqi Qi,Tiecheng Lu
The exploration of new red phosphors is important for the development of white light-emitting diodes (w-LEDs), as existing red phosphors exhibit low efficiency and low performance. This work aims to enhance the photoluminescence characteristics of a red-emitting Gd 2 Zr 2 O 7 :Eu 3+ phosphor by co-doping with Al 3+ . Eu 3+ single-doped and Eu 3+ and Al 3+ co-doped Gd 2 Zr 2 O 7 nanophosphors that could be efficiently pumped by commercial near-UV LED chips were prepared by a modified liquid–solid–solution phase-transfer method. X-ray diffraction data revealed that the synthesized phosphors were well crystallized with single-phase fluorite structure. Scanning electron microscopy images showed that the particle size ranges from 15 to 25 nm. In addition, the optical performance of the samples was characterized by fluorescence spectroscopy and lifetime spectroscopy. The effect of Al 3+ on the luminescence performance of the Eu 3+ -doped Gd 2 Zr 2 O 7 phosphor was studied in detail. The emission intensity of the Gd 1.93 Zr 1 · 97 O 7 :Eu 3+ 0.07 Al 3+ 0.03 phosphor was found to be 620% stronger than that of the single-doped Eu 3+ phosphor. These results unambiguously show that the Gd 1.93 Zr 2- x O 7 :Eu 3+ 0.07 Al 3+ x phosphors are promising candidates for application in w-LEDs.
研究领域:
材料科学
·
光学工程
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Yao Yang,Zhangyi Huang,Chen Shi,Junjing Duan,Gang Cheng,Haomin Wang,Di Wu,Jianqi Qi,Tiecheng Lu
A modified l iquid–solid–solution (LSS) phase transfer method has been applied to synthesize Gd 2 Zr 2 O 7 binary oxide nanoparticles . X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) were employed to reveal the structural, morphological and energetic evolutions of both precursors and Gd 2 Zr 2 O 7 nanoparticle products. The Gd 2 Zr 2 O 7 nanoparticles synthesized using this method exhibit an average crystallite size of 1.7 nm, which have great potential to be applied in thermal barrier coatings (TBCs), solid oxide fuel cells (SOFCs) and nuclear waste immobilizations. Moreover, the method we developed in this study has a high Gd 2 Zr 2 O 7 nanoparticle yield of up to 89%.
研究领域:
材料科学
·
纳米技术
✓ 已验证
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
·
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
·
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
·
2024
·
IF 5.1
Jianjun Zeng,Kuibao Zhang,Yuancheng Teng,Baozhu Luo
The concept of non-stoichiometric design, as a historically significant strategy in material design, plays a crucial role in the development and innovation of materials. Particularly in the domain of red-orange fluorescence, the importance of the rare earth Sm element has been increasingly emphasized. This study successfully prepared non-stoichiometric Gd2Zr2O7 transparent ceramics doped with Sm using combustion and vacuum sintering. X-ray diffraction analysis indicates that the obtained powders are composed of fine defect fluorite structure grains, while the final ceramics exhibit pyrochlore/defect fluorite phase. Initially, non-stoichiometric design optimizes the optical transmittance of ceramics. The maximum transmittance of the X = −0.1 ceramic exhibits the highest transmittance 82.4 % @ 1134 nm. Furthermore, photoelectrons captured by native defects energy levels can transfer to the Sm excited states, optimizing the fluorescence property of ceramics. The fluorescence intensity of the X = 0.8 ceramic is about five times that of the X = 0 ceramic.
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
危险品化学品经营许可证（带存储）