JOURNAL OF PHYSICS D-APPLIED PHYSICS
·
2016
·Vol. 49
·期 34
·345102
·
IF 2.772
Lei Wu,LiDong Dai,HePing Li,YuKai Zhuang,KaiXiang Liu
Yttrium-doped BaZrO3 (BZY) is a promising electrolyte for intermediate-temperature protonic ceramic fuel cells. However, BZY exhibits a high resistance because of the blocking effect of the grain boundaries. In this study, the effect of pressure on undoped and 5% yttrium-doped BaZrO3 (BZY0 and BZY5) were investigated at 0.45–24.01 GPa and 273–673 K with a diamond anvil cell. Their bulk, grain boundary, and total electrical conductivities were determined by impedance spectroscopy and direct-current resistance measurement. Both samples tended to show increasing electrical conductivity with increasing pressure, although each showed a discontinuous inflexion point (at ~14.54 GPa for BZY0 and at ~11.11 GPa for BZY5) indicating a phase transition from a cubic to a tetragonal structure. The samples showed a 3.43 GPa difference in the onset pressure of the structure change. Characteristic parameters, including space charge potential, relaxation frequency, and transport activation energy, were obtained before and after the phase transition. The results suggest that pressure significantly improves oxygen ion conduction in acceptor-doped perovskites oxides.
研究领域:
材料科学
·
能源研究
✓ 已验证
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2021
·
IF 5.302
Le Fu,Bo Li,Guofu Xu,Jiwu Huang,Håkan Engqvist,Wei Xia
Thermal stability of nanocrystallites plays an important role in the manufacturing and application of nanocrystalline ceramics/glass-ceramics. This study explores the effects of thermal treatments on the microstructures of two ZrO 2 -SiO 2 nanocrystalline glass-ceramics (NCGCs), an undoped one and a yttria-doped one. The two as-sintered NCGCs were composed of tetragonal (t) and monoclinic (m) ZrO 2 nanocrystallites, and SiO 2 component was amorphous. t-ZrO 2 and m-ZrO 2 nanocrystallites were metastable during thermal treatment. The content of m-ZrO 2 in the undoped ZrO 2 -SiO 2 NCGC first increased after thermal treating at 850 °C for 5 h, then decreased after thermal treating at and above 950 °C. After thermal treating at 1250 °C for 5 h, t-ZrO 2 nanocrystallites experienced a rapid phase transformation during cooling, resulting the formation of 88.6 vol% m-ZrO 2 . Size-driven phase transformation was utilized to explain the metastability of t-ZrO 2 and m-ZrO 2 nanocrystallites. In contrast, the content of m-ZrO 2 in the yttria-doped ZrO 2 -SiO 2 NCGC continuously decreased with the increase of thermal treatment temperature. The addition of yttria improved the phase stability of t-ZrO 2 up to at least 1250 °C. Crystallite size of both t-ZrO 2 and m-ZrO 2 nanocrystallites increased with the increase of thermal treatment temperature in the two NCGCs. The presence of residual thermal stress in the as-sintered NCGCs changed the lattice spacing of t-ZrO 2 and m-ZrO 2 nanocrystallites, and the stress can be released after thermal treatment. Thermal treatment exerts significant influences on the microstructure of ZrO 2 -SiO 2 NCGCs.
研究领域:
材料科学
·
陶瓷学
✓ 已验证
产品关联
DOI
高影响因子
Frontiers in Chemistry
·
2020
·
IF 3.693
Yang Juncheng,Jia Yihong,Fan Chao,Cheng Yu,Pan Cheng,Huang Benhua,Meng Xu,Zhang Junjie,Zheng Aqun,Ma Xiaomo,Li Xiaoyong,Luque Rafael,Sun Yang
The aqueous room temperature mono-dehydration of sugar alcohols (D-sorbitol and D-mannitol) was conducted using functionalized yttrium oxide nanocatalysts prepared via sol-gel methods. Materials exhibited high selectivity to mono-dehydration products. Solvent and catalyst effects were also investigated and discussed. The introduction of titanium into the yttrium oxide framework would decrease both substrate conversion and mono-dehydration efficiency. In addition, studies of the catalytic mechanism indicate high mono-dehydration efficiency may come from the stability of the formed intermediate during catalysis. This work provides a highly efficient and benign system for catalytic mono-dehydration of sugar alcohols.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Materials Research and Technology-JMR&T
·
2020
·
IF 5.289
Zepeng Lv,Yijie Wu,Jie Dang,Dong Liu,Liwen Hu,Kaiping Du,Haibo Sun
The effect of yttrium on the reaction of tungsten oxide with CO was studied for the preparing various morphologies and size of tungsten carbide. The reaction rate, phase composition, particles size and morphology, surface area of samples were studied by TG (thermogravimetry), XRD (X-ray diffraction), SEM (scanning electron microscopy) and BET (Brunauer–Emmett–Teller), respectively. It was found that the reaction route was following WO 3 → W 18 O 49 → WO 2 → WC at lower temperature, while at higher temperature, an intermediate phase W was formed and then carbonized to WC. During the reaction of pure WO 3 or mixtures (1 wt.% Y(NO 3 ) 3 + WO 3 ) with CO at lower temperature, the final products almost maintained the large irregular block shape. With the increase of temperature, the large WC particles were degraded and the obtained sub-particles became much more dispersed. After the addition of yttrium nitrate, the rod-like sub-particles were transformed into more stable polyhedral-shaped sub-particles with a smaller size. Furthermore, the mechanism of effect of yttrium on prepared tungsten carbides were analyzed in detail.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
·
2020
·Vol. 167
·期 11
·112508
·
IF 3.721
Kui Liu,Wei Wang,Yue Ma,Mingliang Kang,Biao Wang
In this work, the diffusion coefficient and electrocrystallization of yttrium in LiCl-KCl eutectic are typically investigated using different electrochemical techniques such as cyclic voltammetry (CV), chronopotentiometry (CP) and chronoamperometry (CA) techniques. At temperature from 673 to 823 K, the diffusion coefficients of two yttrium concentrations (YCl3 = 3.816 × 10−5 and 9.981 × 10−5 mol ml−1) were determined by CP and CV methods in a range from 0.453 \times 10−5 to 8.25 \times 10−5 cm2 s−1. The nucleation of Y electrodeposition is confirmed to be an instantaneous mode regardless the given temperature, over-potential and concentrations. The morphology of yttrium nuclei and growth evolution on a tungsten surface were characterized by the SEM-EDS. Some individual circular regions corresponding to initial Y nucleation sites are firstly observed on the tungsten surface. The subsequent formed Y nuclei were found to migrate toward those circular nucleation sites to extend its growth on the inside and peripheral of the circle. In addition, no distinct dendritic structure for the Y deposition was observed on the W surface.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
Minerals
·
2023
·Vol. 13
·期 12
·1530
·
IF 2.5
Zongke Zhou,Quan Wan,Wenbin Yu,Xin Nie,Shuguang Yang,Shuqin Yang,Zonghua Qin
The enrichment process of rare earth elements in ion-adsorbed rare earth ores and bauxite is potentially related to the adsorption of rare earth elements by gibbsite. In this paper, lanthanum and yttrium were selected as surrogates of light rare earth elements and heavy rare earth elements, respectively. The effects of adsorption time, solution pH, and background electrolyte concentration on the adsorption of rare earth ions by gibbsite were investigated through batch adsorption experiments. The results showed that the adsorption of rare earth ions by gibbsite can approach equilibrium in 72 h. There is mainly electrostatic repulsion between gibbsite and rare earth ions at pH 4–7, and the adsorption efficiency increases with the increase in solution pH value and background electrolyte concentration. The adsorption process of rare earth ions by gibbsite is more consistent with the pseudo-second-order kinetic and Langmuir single-layer adsorption models. Moreover, based on the structural correlation between clay minerals and gibbsite, the causes for the differences in the adsorption behaviors of rare earth elements on the minerals are discussed. The results of this study help to understand the role of aluminum hydroxide in the migration and fate of rare earth elements in epigenetic environments.Keywords:gibbsite;rare earth element;adsorption;kinetics;thermodynamics
研究领域:
地质学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2021
·
IF 5.706
Juan Ye,Chenyu Chen,Ying Zheng,Dan Zhou,Yunzhen Liu,Denglong Chen,Liufang Ni,Gang Xu,Fanan Wang
The selective one-pot synthesis of lactic acid (LA) from cellulose, and further the raw biomass, on heterogeneous catalysts is the key point for the development of biorefinery technology. Herein, we reported an yttrium (Y) modified siliceous Beta zeolites catalyst via two-step post-synthesis for highly efficient conversion of cellulose to LA. Under condition of 220 °C and 2 MPa N 2 , the cellulose could be transformed to LA with a yield of 49.2 % within 30 min, and the substrate can be extended to various raw biomass. It was demonstrated that the dealumination and modification of Y can efficiently modulate the acidity on the surface of zeolite. The dehydration products HMF and other derivatives were suppressed, and the yield of LA was correlated in line with the acid amount, which were attributed to the increased Lewis acidity originated by Y incorporation. These results contribute to the development of the green and efficient synthesis of bio-chemicals.
研究领域:
生物化学
·
催化化学
·
可再生资源
✓ 已验证
DOI
高影响因子
Materials Science and Engineering B-Advanced Functional Solid-State Materials
·
2024
·
IF 3.9
Hongli Liu,Weiqiang Xie,Qi Zhao,Ying Sui,Zhongxian Liu,Tiangang Zhang,Zhiqiang Zhang,Shuang Sun,Jianwei Jia
SiC fibers have excellent properties such as high-temperature resistance, oxidation resistance, and high strength, and it is an ideal material for high-temperature structures. However, with the continuous development of technology, the application conditions of the material are becoming more and more stringent. Therefore, the properties of SiC fibers need to be further improved to adapt to the ultra-high temperature environment. In this work, yttrium was introduced into the precursor solution using the precursor transformation method, and yttrium-containing SiC fibers were prepared by electrospinning. The microstructure, chemical composition, oxidation resistance, and mechanical properties of the specimens were tested. The results showed that the samples have good thermal stability after ceramization at 1400 °C, and the Y 2 SiO 5 produced in the fiber matrix further improves the antioxidant properties of the fibers. Additionally, the yttrium-containing SiC fibers maintained excellent flexibility, and the high-temperature resistance of SiC fibers was significantly enhanced.
研究领域:
材料科学
·
高温结构材料
✓ 已验证
DOI
高影响因子
Journal of Superconductivity and Novel Magnetism
·
2018
·Vol. 32
·期 5
·1279-1284
·
IF 1.142
Hu Hao,Niu Xiaofei
Magnetoplumbite-type (M-type) barium ferrites doped with different Y–Co doping content Ba 0.95 Y 0.05 Fe 12− x Co x O 19 ( x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5) were successfully prepared by ceramic process and investigated in this paper for the first time. X-ray diffraction were used to analyze the phase of the prepared sample. The scanning electron microscopy (SEM) was used to measure the morphology, and magnetic properties were measured by vibrating sample magnetometer (VSM). The results of XRD show that the single phase of M-type barium ferrites was obtained with the increase of Co content ( x ), but α -Fe 2 O 3 occurred when x exceeds 0.3. The SEM results exhibit the uniform plane hexagonal structures of M-type ferrites with all range of Co doping content. VSM results display that magnetization ( M s ) and coercivity ( H c ) show the same tendency that their values first increase and then decrease with the increase of Co content.
研究领域:
材料科学
·
磁性材料
·
无机功能材料
✓ 已验证
DOI
高影响因子
JOURNAL OF LUMINESCENCE
·
2014
·
IF 2.367
Jiansheng Huo,Jiadan Zhu,Shunhua Wu,Haijie Zhang,Qianming Wang
Red emissive phosphors of YTa 1− x Nb x O 4 :Eu 3+ ( x =0–1) have been successfully synthesized by a molten salt method. Powder characteristics were studied by X-ray diffraction, scanning electron microscopy and photoluminescence spectroscopy. The effects of Nb concentration ( x ), flux nature and firing temperature on photoluminescence behavior of YTa 1− x Nb x O 4 :Eu 3+ were extensively investigated. The results showed that the photoluminescence spectra of the samples exhibited strong red emissions (615 nm) upon the ultraviolet excitation and the emission intensities strongly dependent on the host-lattice composition and particle morphology .
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF PHYSICS-CONDENSED MATTER
·
2016
·Vol. 28
·期 47
·475501
·
IF 2.209
LiDong Dai,Lei Wu,HePing Li,HaiYing Hu,YuKai Zhuang,KaiXiang Liu
The electrical transport properties of undoped and yttrium-doped strontium titanate (Sr(Ti1 – xYx)O3 – δ, x = 0, 0.02) under high pressure were investigated with in situ impedance spectroscopy measurements. A pressure-induced conductivity switching for undoped and 2 mole% Y-doped strontium titanate is observed at around ~10.0 and 7.0 GPa respectively, which are caused by a cubic to tetragonal I4/mcm phase transition. The decrease of the phase transition point of 2 mole% Y-doped strontium titanate can be attributed to larger Y3+ atoms occupying the B-site and the creation of more oxygen vacancies, which lead to octahedra tilting and symmetry breaking. The results of the voltage-bias dependence of grain-boundary impedance of undoped and 2 mole% Y-doped strontium titanate at different pressures revealed that Schottky-type potential barriers formed at grain boundaries are the key factor for the accumulation of oxygen vacancy at the interface under pressure.
研究领域:
材料科学
·
凝聚态物理
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2023
·
IF 9.9
Yizhou Wang,Shuo Geng,Fei Liu,Mengqin Yao,Jun Ma,Jianxin Cao,Ziwei Li
Cerium(IV) oxide (CeO 2 )-based materials are effective catalysts for the synthesis of dimethyl carbonate (DMC) from carbon dioxide (CO 2 ) and methanol (CH 3 OH). Herein, 5% Y–CeO 2 was synthesized by the co-precipitation method. It forms a solid solution structure, which leads to the highest concentration of oxygen vacancies. The Y–V O –Ce active site created by Y 3+ doping enhances the adsorption and activation of CO 2 based on moderately passivating CH 3 OH adsorption. Consequently, 5% Y–CeO 2 exhibited the highest CH 3 OH conversion rate of 0.8% and a DMC yield of 15 mmol⋅(g cat) −1 , which is 1.4 times of pure CeO 2 (reacting in a stainless-steel autoclave at 140 °C with a stirring speed of 1000 r⋅min −1 and an initial pressure of 3.0 MPa for 2 h). An adsorption test and in situ diffuse reflectance infrared Fourier transform spectroscopy showed that 5% Y–CeO 2 could effectively inhibit the formation of triple-bonded methoxy species, and promote the formation of bidentate carbonate and bridged methoxy intermediates, which is conducive to the improvement of reaction activity.
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）