JOURNAL OF NUCLEAR MATERIALS
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2014
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IF 2.016
Xin Wang,Kuo Jiang,Liang Zhou
Powders of (Nd 1− x Ce x ) 2 Zr 2 O 7+ y ( x = 0–1) with pyrochlore structure were prepared by sol-spray pyrolysis and subsequent graphite reduction at 1200 °C. The effects of cerium content on crystal structure, phase stability and microstructure of the (Nd 1− x Ce x ) 2 Zr 2 O 7+ y ( x = 0–1) inert matrix materials were studied. XRD and Raman results presented that all samples were in a single pyrochlore phase. XPS results indicated the cerium was in a single oxidation state of +4. After sintering at 1500 °C for 24 h in air, the sample of x = 1 underwent a phase segregation to Zr 1− x Ce x O 2 solid solutions of tetragonal, metastable tetragonal and cubic phases, the sample of x = 0.9 contained a few tetragonal phase in addition to fluorite phase, the samples of x = 0.5–0.8 had a single phase fluorite structure, the samples of x = 0–0.4 maintained the pyrochlore structure.
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
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2024
·
IF 5.8
Qi Ni,Congcong Ding,Fuxin Liu,Fen Luo,Xiaoyan Shu,Yulu Fu,Xirui Lu
Multi-component high-entropy pyrochlore (HEP) offers several advantages compared to single-component pyrochlore in solidifying radioactive waste , including the ability to solubilize multiple types of waste and lower leaching rates (LRs) of radionuclides . In this study, we successfully synthesized HEP (Y 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 ) 2 Zr 2 O 7 and immobilized Ce, a simulated nuclide of Pu at 1500 °C for 48 h using a free occupied design approach. The Raman, XRD , and Rietveld refinement results showed that the immobilization limit for Ce fell between 20 wt .% and 30 wt .%. Notably, the ordered pyrochlore phase gradually transformed into the defective fluorite phase with an increase in Ce content. Moreover, the leaching tests demonstrated the excellent stability of the matrix, with the normalized LR for Ce reaching 10 −7 g·m −2 ·L −1 after 42 days at 90 °C. These findings collectively suggest that HEP (Y 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 ) 2 Zr 2 O 7 holds promise as a substrate for immobilizing radioactive waste in the future.
研究领域:
材料科学
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核能工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
ADVANCED FUNCTIONAL MATERIALS
·
2023
·Vol. 34
·期 3
·2306176
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IF 19
Qingren Zhang,Tongtong Liu,Hengyu Guo,Yanan Chen,Yajing Di,Zhengping Zhang,Feng Wang
Pyrochlore ruthenates are highlighted as candidates to replace iridium oxide as oxygen evolution reaction (OER) electrocatalyst, but their designable geometric configurations and composition modulations are hampered by the high-temperature (≈1100 °C) and long-time calcination (more than 12 h), which further decreases the technical and economic feasibility. In this work, an energy- and time-saving approach is proposed to prepare pyrochlore yttrium ruthenate at a much lower calcination temperature (600 °C) and shorter calcination time (6 h) just by inducing A-site substitutions of lead ions (YPRO). The local microstrain derived from Pb provides the surficial compression and extra driving force to overcome the strain energy of phase-transition resistances and the obtained low-temperature YPRO exhibits enriched pores, deficient geometries, shortened Ru─O bond, and enlarged Ru─O─Ru bond angle, which further modify the electronic structure, involving of the rearranged band alignment and the eliminated bandgap. The regulated morphologic, geometric, and electronic structures in YPRO synergically boost the electrocatalytic OER performance (4.8-fold and 30.0-fold enhancements compared with pyrochlore yttrium ruthenate and commercial iridium dioxide (IrO 2 ), respectively) in universal pH conditions. This substitution-induced strain engineering on phase transition should also be effective for other high-temperature materials and trigger their diverse intriguing properties.
研究领域:
材料科学
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电化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2022
·
IF 6.371
Yuhan Wang,Jinpeng Zhu,Gang Shao,Hailong Wang,Mingliang Li,Hongxia Lu,Rui Zhang
A new method is proposed to predict the formation of high-entropy single-phase oxide with a pyrochlore structure synthesis from non-equivalent principal elements. Based on this concepte, the La 2 B 2 O 7 (B = Zn 2+ , Mg 2+ /Ni 2+ , Ce 4+ /Zr 4+ /Hf 4+ /Sn 4+ /Ti 4+ , W 6+ , Mo 6+ ) were designed, in which high-entropy La 2 (ZnMgZrWMo) 2 O 7 , La 2 (ZnMgHfWMo) 2 O 7 and La 2 (ZnMgSnWMo) 2 O 7 pyrochlore ceramics were successfully prepared by solid-phase sintering. The microstructure of the entropy-stabilized phase was demonstrated using X-ray diffraction and elemental mapping, and the thermal properties including the thermal expansion coefficient and thermal conductivity were analyzed. The results show that La 2 (ZnMgZrWMo) 2 O 7 has a higher thermal expansion coefficient (13.9 × 10 –6 K –1 ) and lower thermal conductivity (0.8 W/m·K) than its corresponding single-components compound. In addition, La 2 B 2 O 7 (B = Zn 2+ , Mg 2+ , Zr 4+ /Hf 4+ /Sn 4+ , W 6+ , Mo 6+ ) pyrochlore high-entropy ceramics exhibit good calcium – magnesium – aluminosilicate (CMAS) resistance, the apatite protective layer generated after the reaction of La with CMAS effectively prevents further corrosion. This study suggests a novel method for predicting the formation of high-entropy single-phase oxides of pyrochlore structures and provides a new design concept for anti-CMAS corrosion materials.
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
·
2022
·
IF 5.532
Yan Wang,Jin Wang,Junxia Wang,Xusheng Li,Yijie Tang,Nan Li
MgO-Nd 2 Zr 2 O 7 composite ceramic is a promising candidate as an inert matrix material for the transmutation of Pu and minor actinide. In this work, the MgO-Nd 2 Zr 2 O 7 composite ceramics (hereafter M-NZO) with 30–70 wt% mass percent of MgO were successfully prepared at 1500 °C for 24 h via direct solid-state reaction one-step method. This method achieved the integration of Nd 2 Zr 2 O 7 pyrochlore synthesis and M-NZO composites sintering, which shows a significant improvement in the simplification of the preparation process than the traditional two-step method. The structural properties and compactness of the as-prepared composite ceramics were systematically investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM). It was confirmed that the as-prepared M-NZO ceramics are composed of only crystalline MgO and Nd 2 Zr 2 O 7 phases, and the mass fractions of two phase are almost the same as the designed nominal chemical composition. The composite ceramics showed remarkable densification and the relative density is higher than 98.2%.
研究领域:
材料科学
·
核能工程
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Xiuhua Ji,Yanhao Song,Jiarun Wang,Yi Ding,Shiyin Ji,Tao Duan
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 Ca 1-x Ho 2x Zr 1-x Ti 2 O 7 (0.1 ≤ x ≤ 1.0) ceramics were prepared by solid state synthesis and sintering at 1400 °C for 48 h twice. Powder X-ray Diffraction (XRD), Backscattered Scanning Electron Microscopy with Energy-Dispersive X-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 be 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 in 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.%. In 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 Zr occupied A site (16d) and Ti entered in B site (16c). The findings would provide more insights into zirconolite–pyrochlore ceramic system.
研究领域:
材料科学
·
核化学与放射化学
✓ 已验证
产品关联
DOI
高影响因子
LANGMUIR
·
2025
·
IF 3.9
Qi Feng,Lu Sun,Penghui Zhu,Xuguang Li,Xiaofeng Miao,Jing Zhao,Mark C. Williams,Chi Zhang
Significant progress has been achieved in enhancing the oxygen evolution reaction (OER) performance of pyrochloric oxides through geometric and electronic structure regulation. However, the issue of A-site cation segregation in these materials remains underexplored. In this study, Bi2Ru2O7, a promising OER electrocatalyst, is synthesized via a sol–gel method, and its surface is modified using l-ascorbic acid to address Bi3+ segregation. This treatment selectively removes the Bi2O3 passivation layer, inducing an amorphous RuOx layer that forms a heterostructure with crystalline Bi2Ru2O7. This engineered structure significantly enhances catalytic performance, reducing the overpotential to 259 mV at 10 mA cm–2 and maintaining stability after continuous operation for >30 h. Comprehensive characterization, electrochemical testing, and density functional theory calculations reveal that the improvements stem from an increased number of oxygen vacancies and enhanced electron transfer. This work underscores the importance of surface engineering to mitigate A-site segregation, providing a new strategy for optimizing Ru-based pyrochlores in energy conversion technologies.
研究领域:
材料科学
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电化学
·
能源转换技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Chenglin Zhang,Hailu Wang,Yuanbing Li
In this paper, (La 0.2 Pr 0.2 Nd 0.2 Sm 0.2 Eu 0.2 ) 2 Zr 2 O 7 high-entropy ceramic fiber membrane (HE-RE 2 Zr 2 O 7 fiber) and (La 0.2 Pr 0.2 Nd 0.2 Sm 0.2 Eu 0.2 ) 2 Zr 2 O 7 /ZrO 2 composite ceramic fiber (HE-RE 2 Zr 2 O 7 /ZrO 2 fiber) were prepared by electrospinning. XRD analysis showed that HE-RE 2 Zr 2 O 7 fibers and HE-RE 2 Zr 2 O 7 /ZrO 2 fibers changed from defective fluorite phase to pyrochlorite phase at 900°C–1200 °C, and ZrO 2 phase gradually appeared at 1200 °C for HE-RE 2 Zr 2 O 7 /ZrO 2 fibers. After holding at different temperatures for 1 h, the grain size growth rate of HE-RE 2 Zr 2 O 7 /ZrO 2 fibers was significantly slower than that of HE-RE 2 Zr 2 O 7 fibers. By doping a small amount of ZrO 2 in high-entropy ceramic fibers, the grain growth rate can be further slowed down.
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Jianjun Zeng,Kuibao Zhang,Lei Zeng,Shuguang Zhou,Min Qin
Recently, high-entropy oxide ceramics have become a hot topic in the field of high entropy materials. In this paper, multicomponent pyrochlore A 2 Zr 2 O 7 transparent ceramics were prepared via vacuum sintering using combustion synthesized nanopowders . The phase analysis results indicate that the powders exhibit defective fluorite structure and the ceramics are in pyrochlore structure. The structural order degree of ceramics varies with the increase of incorporated components. It is found that the grain size of A 2 Zr 2 O 7 ceramics is related with the component of A-site. The main fracture mode of final ceramics exhibit typical transgranular fracture . The multicomponent A 2 Zr 2 O 7 ceramics exhibit excellent optical transmittance, and the highest in-line transmittance reaches to 80% for #A2ZO ceramic at 1880 nm.
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
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Tao Deng,Zhen Liu,Tengfei Hu,Kai Dai,Zhigao Hu,Genshui Wang
The comprehensive performance of ferroelectric ceramic materials is a significant factor limiting the practical application. In this work, a novel strategy of constructing diphase compounds is proposed to significantly enhance the energy storage properties of Bi 0.5 Na 0.5 TiO 3 -based ceramics. A composite ceramic of pyrochlore phase Sm 2 Ti 2 O 7 modified perovskite phase Bi 0.5 Na 0.5 TiO 3 is successfully prepared and systematically studied. As the concentration of Sm 2 Ti 2 O 7 increases, the dielectric breakdown strength is greatly strengthened because of expanded band gap and shrunk grain size, and the relaxor behavior is enhanced due to the effect of linear character pyrochlore. As a result, the optimized composition demonstrates excellent energy storage properties including high recoverable energy storage density ( W rec ) of 6.387 J/cm 3 at 402 kV/cm, superior stability of temperature (<6% variation in − 120 ∼ 120 °C), frequency (∼4% variation in 5 ∼ 500 Hz) and cycling (∼2% variation within 10 6 cycles). Besides, fast discharge behavior of t 0.9 ∼ 29.4 ns and high power density of 80.49 MW/cm 3 at 200 kV/cm are also achieved. This study presents a novel strategy to enhance the performance of BNT-based materials through forming composite ceramic, which is anticipated to be a general method for other material systems as regards the design of advanced energy storage ceramics.
研究领域:
材料科学
·
能源存储技术
✓ 已验证
DOI
高影响因子
MATERIALS SCIENCE FORUM
·
2021
·
IF 0
Li Qiong An,Rong Wei Shi,Run Hua Fan,Takashi Goto
Y2Ti2O7 transparent ceramic was fabricated by reactive sintering using spark plasma sintering at 1673 K for 2.7 ks. The sintered body exhibited a cubic pyrochlore structure and uniform microstructure with an average grain size of 2.9 μm. The transmittance reached 73% at a wavelength of 2000 nm after annealing at 1023 K for 21.6 ks.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
DOI
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Xiaobing Jili,Libin Gao,Jinxu Liu,Minghao Liu,Bowen Deng,Hongwei Chen,Jihua Zhang
The multi-layer ceramic capacitor (MLCC) is prepared with Bi 1.5 MgNb 1.5 O 7 (BMN) pyrochlores, which has medium dielectric constant, large dielectric tunability, and especially the very small dielectric loss. The multilayer ceramic capacitors with Bi 1.5 MgNb 1.5 O 7 as the dielectric material are prepared by a tape-casting method. The dielectric constant of the BMN thick film was observed to be superior to that of the bulk material, indicating its potential application in electronic devices. The increase in dielectric constant during the preparation of multilayer ceramic capacitors was explained by investigating the interdiffusion between the ceramic thick films and the electrodes. The BMN thick films and Ag 0.7 /Pd 0.3 electrodes showed a dense microstructure and serial interfaces when sintering at 1050 °C for 1.5 h. The capacitor exhibited good temperature stability with a dielectric constant temperature coefficient of −249.94 ppm/°C, a relative dielectric constant of 216, and a dielectric loss of 0.00036. Provides insights for the development and optimization of high-performance dielectric tunable electronic device.
研究领域:
材料科学
·
电子工程
✓ 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）