JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2024
·
IF 3.5
Le Fu,Wenjun Yu,Bohan Wang,Ying Deng
Extensive efforts have been devoted to investigate the distribution of dopants in ceramics. However, one critical question remained barely explored, which is the redistribution of dopants between amorphous and crystalline phases during fast sintering of ceramics. Here we address this gap by observing the redistribution of five selected dopants (Y, Ce, Yb, Hf, and Ta) in ZrO 2 –SiO 2 nanoceramics during sintering. We designed two groups of experiments: In group one, dual-phase amorphous particles were sintered with multicomponent crystalline ones. The former particles were ZrO 2 –SiO 2 glass, whereas the latter ones consisted of ZrO 2 solid-solution nanocrystallites (SSNCs) embedded in an oxide glass containing Zr, Si, Y, Ce, Hf, Yb, and Ta. In group two, dual-phase crystalline particles were sintered with multicomponent amorphous ones. The former particles were composed of ZrO 2 nanocrystallites (NCs) embedded in an amorphous SiO 2 matrix, whereas the latter ones were oxide glass containing Zr, Si, Y , Ce, Hf, Yb, and Ta. Redistribution of the dopants from the glass to ZrO 2 NCs occurred in the two groups, that is, the five dopants migrated from the glass matrix into the ZrO 2 NCs, forming ZrO 2 SSNCs. The redistribution of the dopants not only increased the configuration entropy of the ZrO 2 NCs but also benefited the network structure integrity of SiO 2 glass. The dopant redistribution process was driven by the minimization of the studied material's free energy. The reported results are important for understanding the redistribution behaviors of dopants and are expected to provide new insights to design new ceramics via the multielement co-doping strategy.
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
ACS Applied Nano Materials
·
2019
·
IF 0
Benxue Liu,Min Gao,Xiaochan Liu,Xinfu Zhao,Jing Zhang,Xibin Yi
Compared with single-component aerogels, hybrid aerogels with multiple components possess enhanced properties, especially high thermal stabilities. Thermal stability improvement depends on the mixing between the various components. In the present research, a ZrO2/SiO2 hybrid aerogel was representatively chosen to study the mixing behaviors and resultant thermal stabilities. A series of ZrO2/SiO2 hybrid aerogels were synthesized by using different sol–gel parameters to study shrinkage, nanopore collapse, and crystallization behavior upon heat treatment. The sol–gel hybridization of weakly branched ZrO2 and SiO2 clusters was found to provide maximum mixing of ZrO2/SiO2. The highly mixed hybrid aerogel, with a ratio of 86/14 w/w ZrO2/SiO2, showed the best thermal stability. The thermally stable ZrO2/SiO2 hybrid aerogel, after incorporation into a mullite fiber blanket, showed very low thermal conductivities of 0.026 ± 0.001, 0.037 ± 0.001, and 0.058 ± 0.002 W/(m K) at 600, 800, and 1000 °C, respectively. It was suggested that weakly branched ZrO2 and SiO2 clusters preferred to freely tangle with each other during the preparation procedure, achieving the most highly mixed ZrO2/SiO2 hybrid with the maximum synergistic effect. This hybrid strategy may provide pathways in designing other multiple-component hybrid aerogels.
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
RSC Advances
·
2017
·Vol. 7
·期 12
·7140-7149
·
IF 3.108
Yuchao Xu,Zongzhang Liu,Zheng Han,Minhua Zhang
ZnO promoted ZrO2–SiO2 catalysts synthesized by a sol–gel method were investigated in the two-step ethanol transforming to 1,3-butadiene process. The influence of promoters and the preparation method of the catalysts on the catalytic performance were studied in detail and the reaction conditions were optimized. The as-prepared catalysts were characterized by BET, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Resonance (FT-IR), X-ray photoelectron spectroscopy (XPS), FT-IR spectroscopy of adsorbed pyridine (Py-IR) and temperature-programmed desorption of NH3 (NH3-TPD). ZnO added ZrO2–SiO2 catalysts show the best catalytic activity and the catalysts prepared by the hybrid sol–gel method were superior to those prepared by the sol–gel coupled with impregnation method. The addition of promoters in the ZrO2–SiO2 system decreased the total acidity and lowered the selectivity to dehydration products. The best performance with ethanol/acetaldehyde conversion of 40.7% and 1,3-butadiene selectivity of 83.3% was reached at 310 °C, ethanol/acetaldehyde mole ratio of 3.5 and WHSV of 1.4 h−1 using a 0.5 wt% ZnO doped ZrO2–SiO2 catalyst.
研究领域:
催化化学
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材料科学
·
能源化工
✓ 已验证
产品关联
DOI
高影响因子
SURFACE & COATINGS TECHNOLOGY
·
2017
·
IF 2.589
Xue-Ling Wei,Na Li,Wen Jun Yi,Li-Jun Li,Zi-Sheng Chao
The super-hydrophobic (SH) porous ceramics material with good stability was successfully prepared via the hydrothermal growth of CeO 2 micro/nano-structure and the subsequent dip-coating of low surface energy substance 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES) over the surfaces of ZrO 2 -SiO 2 porous ceramics substrate. The surface morphology , chemical composition and wettability of material were investigated by means of SEM, EDS, XRD , FT-IR, and contact angle measurement. It was found that a layer of CeO 2 nano-flowers had been attached over the surfaces of ZrO 2 -SiO 2 porous ceramics substrate, using the optimized concentration of CeNO3 precursor, and after the grafting of PFDTES, the super hydrophobicity of the obtained material was achieved, with the water contact angle being as high as 162° and sliding angle being approximately 0°. Particularly, the super hydrophobicity was found to occur also in the pores of the obtained material. The obtained material was found to possess the significantly large thermal and chemical stabilities.
研究领域:
材料科学
·
表面工程
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
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2022
·
IF 5.723
Boyong Ye,Ruru Zhou,Caili Wang,Zixuan Wang,Zixin Zhong,Zhaoyin Hou
Polylactic acid (PLA) is popularly used to replace some petroleum-based polymers due to its biodegradability. However, biodegradation of waste PLA requires specific bacteria, stringent conditions and long time. Catalytic recycling of waste PLA to valuable added products rather than composting is a sustainable green routine. In this work, catalytic alcoholysis of waste PLA to methyl lactate (MLA) was carried out over a SiO 2 @UiO-66 derived solid acid (SO 2– 4 /ZrO 2 /SiO 2 ). Characterizations indicated that SO 2– 4 /ZrO 2 /SiO 2 processed large surface area and homogenously dispersed acid sites, and it exhibited excellent performance for the alcoholysis of waste PLA under mild conditions. At 140 o C, the yield of MLA is 92.7% within 5 h, and SO 2– 4 /ZrO 2 /SiO 2 could be recycled at least five times without obvious loss of activity. The specific yield of MLA over SO 2– 4 /ZrO 2 /SiO 2 reached 2678 mg-MLA/g-cat/h, which was higher than that of H 3 PW 12 O 40 , Amberlyst-45, H β , HZSM-5 and α -ZrP. At the same time, SO 2– 4 /ZrO 2 /SiO 2 was also capable of the alcoholysis of waste PLA-based products. A possible pathway of PLA alcoholysis over SO 2– 4 /ZrO 2 /SiO 2 catalyst was proposed.
研究领域:
化学工程
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材料科学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2023
·
IF 5.7
Le Fu,Bohan Wang,Yabin Zhu,Tielong Shen,Ying Deng,Guofu Xu,Jiwu Huang,Yucheng Feng,Liangting Sun,Wei Xia
Developing new radiation-resistant materials and understanding the structural damages caused by radiation are persistent goals of material scientists. Here, we report on the structural integrity and damage to ZrO 2 -SiO 2 nanocrystalline glass-ceramics after radiation with 1.4 MeV He ions at three different fluences: 1.0 × 10 16 ions/cm 2 (low), 5.0 × 10 16 ions/cm 2 (moderate), and 1.0 × 10 17 ions/cm 2 (high) at 500 °C. Grazing incident X-ray diffraction shows the tetragonal-ZrO 2 to monoclinic-ZrO 2 phase transformation induced by microstrain from the irradiation. The addition of yttrium indicated tetragonal-ZrO 2 stabilization effect during irradiation. The irradiated glass-ceramics show a Raman signal-enhancement effect probably related to the electronic structure changes of the amorphous SiO 2 component in the glass-ceramics. The formation of microcracks and lattice defects within ZrO 2 nanocrystallites is the main structural damage caused by irradiation. There was no observable amorphization of ZrO 2 nanocrystallites due to irradiation. No obvious He bubbles were detected, either. The formation of microcracks results in a decrease of in the nanohardness of the glass-ceramics. The results provide fundamental experimental data to understand the structural integrity and damage caused by radiation, which could be useful to design radiation‐resistant nanocrystalline glass-ceramics for extremely radioactive environments.
研究领域:
材料科学
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核能工程
✓ 已验证
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2024
·Vol. 107
·期 9
·6477-6492
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IF 3.5
Le Fu,Wenjun Yu,Zixu Wen,Jinling Liu
Flash sintering has been used to consolidate a wide range of ceramics and ceramic composites. However, flash sintering of ceramic nanocomposite with a substantial amorphous phase is rarely studied. Meanwhile, the effects of yttrium addition on the flash sintering behaviors and microstructures of ZrO 2 -based ceramic nanocomposite remain unknown. Herein, ZrO 2 -SiO 2 crystalline-amorphous ceramic nanocomposites (CACNs) with different contents of amorphous phase and two types of yttrium dopants were sintered by flash sintering. Results showed that the content of amorphous phase (SiO 2 ) had significant effects on the flash sintering behavior. The CACN with 65 mol% SiO 2 was nonflash sinterable due to the high electric resistivity of SiO 2 , whereas, the CACN with 45 mol% SiO 2 can be flash sintered to high densification within 35 seconds. The flash-sintered CACNs consisted of ZrO 2 nanocrystallites distributed in an amorphous SiO 2 matrix. Flash sintering enhanced the tetragonal-to-monoclinic phase transformation of ZrO 2 . In addition, influences of yttrium dopant on CACNs were also investigated. Yttrium dopants can rapidly dissolve in ZrO 2 lattices and show a tetragonal phase stabilization effect during flash sintering. Firework-like ZrO 2 microcrystallites formed by dendritic growth were observed close to the cathode region, which was attributed to athermal electric field effects and the formation and aggregation of oxygen vacancies at the cathode region. The results would provide guidance for fabricating CACNs via flash sintering.
研究领域:
材料科学
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陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2015
·Vol. 5
·期 126
·103982-103988
·
IF 3.84
Zheng Han,Xiang Li,Minhua Zhang,Zongzhang Liu,Meixiang Gao
A series of ZrO2–SiO2 catalysts synthesized by sol–gel method were investigated for the 1,3-butadiene formation from bioethanol and acetaldehyde. The influence of ZrO2 content and reaction conditions on catalytic performance were studied. The catalysts were characterized by N2 adsorption–desorption analysis, temperature-programmed desorption of NH3 (NH3-TPD), IR spectroscopy of adsorbed pyridine (Py-IR), Fourier Transform Infrared Resonance (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscope (TEM). These characterization results indicated that suitable intensity of acid sites, especially Lewis acid, are very crucial to obtain an active catalyst. The catalysts showed significantly higher selectivity for C4 chemicals, and 2 wt% ZrO2 content reached the highest selectivity to BD (69.7%), at space velocity (WHSV) of 1.8 h−1.
研究领域:
催化化学
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可再生资源转化
·
材料科学
✓ 已验证
DOI
高影响因子
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
·
2022
·
IF 6.044
Le Fu,Bohan Wang,Junjie Song,Chenglong Xu,Guofu Xu,Qiuan Sun,Jiwu Huang,Håkan Engqvist,Wei Xia
The content of crystalline phase plays a significant role in manipulating the microstructure and mechanical properties of glass-ceramics. This study aims at exploring the optimum content of crystalline phase in ZrO 2 –SiO 2 nanocrystalline glass-ceramics (NCGCs) in terms of obtaining the highest mechanical properties. To this end, the mechanical properties of ZrO 2 –SiO 2 NCGCs with 70 mol%, 75 mol%, 80 mol% ZrO 2 were tested and compared with those of the previously prepared NCGCs with ZrO 2 content ranging from 35 mol% to 65 mol%. Results showed that 65 mol% was the optimum content of ZrO 2 in terms of obtaining the highest flexural strength . The flexural strength of NCGCs with ZrO 2 content over 65 mol% was lower than that of the NCGCs with 65 mol% ZrO 2 . This was because the NCGC with 65 mol% ZrO 2 had a homogenous microstructure, with ZrO 2 nanocrystallites homogeneously distributed in an amorphous SiO 2 matrix. Whereas, when ZrO 2 content was increased to 75 mol%, ZrO 2 nanocrystallites were not homogeneously distributed in the SiO 2 matrix anymore. The formation of SiO 2 “holes/canyon” due to ZrO 2 grain coalescence resulted in the decrease of flexural strength. The fracture mechanism and wear properties of the NCGCs were also investigated.
研究领域:
材料科学
·
工程学
✓ 已验证
DOI
高影响因子
APPLIED ENERGY
·
2019
·
IF 8.426
Zain Ali Saleh Bairq,Hongxia Gao,Yufei Huang,Haiyan Zhang,Zhiwu Liang
A significant impediment to the widespread adoption of amine-based post-combustion technique for CO 2 capture from flue gas is the huge energy demand for amine solvent regeneration. In this study, five novel bifunctional heterogeneous catalysts e.g., SO 4 2− /ZrO 2 /SiO 2 with different molar ratios of zirconia and SO 4 2− /ZrO 2 as a parent catalyst were synthesized and applied to evaluate their effectiveness in enhancing the CO 2 desorption and solvent regeneration of 5M monoethanolamine solution with CO 2 loading of 0.5 ± 0.01 mol CO 2 /mol monoethanolamine at 97 °C. The catalysts were characterized by Fourier transform-infrared spectrometry, pyridine-infrared spectroscopy, X-ray diffraction, N 2 -adsorption-desorption, and ammonia-temperature programmed desorption. The results demonstrated that these catalysts can significantly reduce the heat duty for CO 2 desorption by 36.48% compared to without catalyst and enhance desorption rate by 35.1%. The results also showed that SO 4 2− /ZrO 2 /SiO 2 15% presented the highest efficiency compared to the other SO 4 2− /ZrO 2 /SiO 2 ratios and the super solid acid catalyst SO 4 2− /ZrO 2 . Additionally, to investigate if the catalysts induce any unfavorable effects on the amine, the absorption of CO 2 by regenerated amine solvent was studied. Finally, a reaction mechanism for the amine solvent regeneration with the synthesized catalyst e.g., SO 4 2− /ZrO 2 /SiO 2 was suggested.
研究领域:
化学工程
·
环境科学
✓ 已验证
DOI
高影响因子
JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
·
2018
·Vol. 87
·期 3
·734-742
·
IF 1.745
Wang Xiaoqing,Wu Zongxiao,Zhi Mingjia,Hong Zhanglian
Abstract We reported the preparation of a series of ZrO 2 -SiO 2 composite aerogels via the sol-gel reaction between the zirconium source (ZrOCl 2 ·8H 2 O) and the gel initiator (mercaptosuccinic acid-triethoxyvinylsilane). Such novel gel gelator was prepared by the thiol-ene click reaction using triethoxyvinylsilane (VTES) and mercaptosuccinic acid (MSA). The unique molecule structure of the gel initiator allows the in-situ modification of ZrO 2 with SiO 2 in the sol-gel reaction, which was achieved by the hydrolysis and polycondensation of siloxane with the change of the pH spontaneously. SiO 2 with the controllable content can be in-situ introduced into ZrO 2 backbone. As a result, the composite aerogel showed better thermal stability compared with pristine ZrO 2 aerogel, proved by the following facts: (i) the aerogels remained amorphous after calcination in air at 600 °C; (ii) the specific surface area maintained at 53.4 m 2 /g when the temperature rising to 1000 °C.
ZrO 2 -SiO 2 composite aerogels with improved thermal stability have been prepared via the “thiol-ene” click section
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
RSC Advances
·
2018
·Vol. 8
·期 59
·34069-34077
·
IF 2.936
Minhua Zhang,Xuechao Tan,Tong Zhang,Zheng Han,Haoxi Jiang
A deactivation study on the ethanol/acetaldehyde conversion to 1,3-butadiene over a ZnO promoted ZrO2–SiO2 catalyst prepared by a sol–gel method was performed. The samples were characterized by N2 adsorption–desorption isotherms, scanning electron microscopy (SEM), NH3 temperature programmed desorption (NH3-TPD), X-ray powder diffraction characterization (XRD), thermogravimetric analyses (TGA), Fourier transform infrared resonance (FT-IR), 13C magic-angle spinning nuclear magnetic resonance (13C NMR) and X-ray photoelectron spectroscopy (XPS). The pore structure characteristics and surface acidity of Zn0.5–Zr–Si catalysts were largely decreased with time-on-stream and no crystal structure was formed in the used catalyst, indicating that the deactivation was caused by carbon deposition. Two main types of carbon deposition were formed, namely low-temperature carbon deposition with the oxidation temperature of around 400 °C and high-temperature carbon deposition with the oxidation temperature of 526 °C. The carbon species were mainly composed of graphitized carbon, amorphous carbon, carbon in C–O bonds and carbonyls. The deactivated catalyst could be regenerated by a simple oxidation process in air. Adding a certain amount of water into the feed had a positive effect on reducing the carbon deposition.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）