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Structure-dependent electrocatalytic activity of La_(1-x)SrxMnO_3 for oxygen reduction reaction

Science China Chemistry 2015年第5期58卷 871-878页

作者： Guangjin Wang Tian Xu Sheng Wen Mu Pan College of Chemistry and Materials Science Hubei Engineering University State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Hubei Provincial Key Laboratory of Fuel Cell

The electrocatalytic activity toward oxygen reduction reaction is studied on the perovskite oxide La~_xbrxMnt）3, as preparea under different firing temperatures. X-ray diffraction shows that three different crystal phases featuring tetragonal, cubic, and orthorhombic symmetries form with increasing crystallinities. The electrocatalytic activity is characterized by cyclic voltam- metry and linear sweeping voltammetry for the three phases of La1-xSrxMnO3. We find that the tetragonal phase has the best catalytic activity among the three crystal phases, with the largest onset potential of 0.147 V. The synergistic effect between the volume per unit cell and crystallinity is indicated to account for the good catalytic activity of the tetragonal phase.

关键词： perovskite oxide La1-xSrxMnO3 crystal phase crystallinity oxygen reduction reaction

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Electron-pinned defect-dipoles for SrTiO3-based ceramics with high permittivity and low dielectric loss

Electron-pinned defect-dipoles for SrTiO3-based ceramics wit...

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IEEE International Symposium on Applications of Ferroelectrics (ISAF)

作者： Zichen He Minghe Cao Nana Wang Qi Zhang Hua Hao Zhonghua Yao Hanxing Liu State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan Hubei People's Republic of China

ISBN: (纸本)9781509018727

Sr(Nb 0.5 Al 0.5 ) x Ti 1-x O 3 (x=0, 0.02, 0.04, 0.06) ceramics were obtained via solid-state reaction method and sintering in air at 1540°C. The grain size of SrTiO 3 ceramics decreased with Nb 2 O 5 and Al 2 O 3 doping content. Sr(Nb 0.5 Al 0.5 ) x Ti 1-x O 3 ceramics exhibit a giant permittivity of about 10500 and low dielectric loss of 0.03 measured at room temperature and 1kHz. According to the XRD, XPS, and ac conductivity analysis, this excellent dielectric behaviors of Sr(Nb 0.5 Al 0.5 ) x Ti 1-x O 3 ceramics would originate the bond[Ti 4+ ·e-V O .. -Ti 4+ ·e], in which the electrons were bound by Ti 4+ and V O .. leading to low dielectric loss. Compared with SrNb 0.01 Ti 0.99 O 3 and In addition, SNAT ceramics were also sintered in oxygen atmosphere and nitrogen atmosphere to verify the existence of [Ti 4+ ·e-V O .. -Ti 4+ ·e].

关键词： Ceramics Permittivity Dielectric losses Temperature measurement Dielectric measurement Conductivity

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Three-dimensional porous V2O5 hierarchical octahedrons with adjustable pore architectures for long-life lithium batteries

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Nano Research 2015年第2期8卷 481-490页

作者： Qinyou An Pengfei Zhang Fangyu Xiong Qiulong Wei Jinzhi Sheng Qinqin Wang Liqiang Mai State Key Laboratory of Advanced Technology for Materials Synthesis and Processing WUT-Harvard Joint Nano Key LaboratoryWuhan University of Technology Wuhan Hubei 430070 China

Three-dimensional （3D） porous V2O5 octahedrons have been successfully fabricated via a solid-state conversion process of freshly prepared ammonium vanadium oxide （AVO） octahedrons. The formation of AVO octahedrons is a result of the selective adsorption of capping reagents and the favourable supersaturation of growth species. Subsequently, 3D porous V2O5 octahedrons were obtained by simple thermolysis of the AVO octahedrons via a calcination treatment. As cathode material for lithium batteries, the porous V2O5 octahedron cathode exhibits a capacity of 96 mAh·g^-1 at high rate up to 2 A·g^-1 in the rang of 2.4 4 V and excellent cyclability with little capacity loss after 500 cycles, which can be ascribed to its high specific surface area and tunable pore architecture. Importantly, this facile solid-state thermal conversion strategy can be easily extended to controllably fabricate other porous metal oxide micro/nano materials with specific surface textures and morphologies.

关键词： V2O5 octahedron adjustable pore long-life lithium battery

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High-temperature diffusion behavior of ZrC in C matrix and its promotion on graphitization

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Transactions of Nonferrous Metals Society of China 2016年第8期26卷 2257-2262页

作者： Zhong-wei ZHANG Qiang ZHEN Feng ZHENG Fei LU Ce-wen NAN Rong LI Jun-shan WANG State Key Laboratory of New Ceramics & Fine Processing School of Materials Science and EngineeringTsinghua University Beijing 100084 China Science and Technology on Advanced Functional Composites Laboratory Aerospace Research Institute of Materials and Processing Technology Beijing 100076 China Research Center of Nano Science and Technology Advanced Material Composite and Dispersion Technology Engineering Research Center of Ministry of Education of China Shanghai University Shanghai 200444 China

C/C composite material is widely used in aerospace field and others, however, it is easy to be oxidized at high *** order to improve the oxidation resistance, ZrC is introduced as an oxidation inhibitor used in matrix modification of C/C composite material. Flat plate samples of ZrC/C composite materials were prepared by hot-pressing sintering. The degree of graphitization increases with rising sintering temperature, and layer structure of carbon matrix is observed clearly in the sample treated at 2273 K. Diffusion behavior of Zr in C matrix at high temperature is studied, which can be generally expressed as D=3.382×10?11 exp[2.029×105/(RT)]. The diffusion of Zr in C matrix leads to the over-saturation of C in the micro area and the oversaturated C precipitates as graphite. This continuous process promotes the transformation of carbon to graphite.

关键词： ZrC carbon material diffusion graphitization

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Dielectric properties and relaxation behavior in Mn-doped Ca0.6Sr0.4TiO3 ceramics for energy storage

Dielectric properties and relaxation behavior in Mn-doped Ca...

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IEEE International Symposium on Applications of Ferroelectrics (ISAF)

作者： Lin Zhang Juan Xie Qi Xu Minghe Cao Hua Hao Zhonghua Yao Hangxing Liu State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan Hubei People's Republic of China

ISBN: (纸本)9781509018727

Linear dielectric materials are ideal options for energy storage application due to the typical high energy storage efficiency and breakdown strength. In the present work, pore free Ca 0.6 Sr 0.4 TiO 3 (CST) ceramics with various amounts of Mn dopants (0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 1.0%, 1.5%, 2.0%) were prepared via solid state reaction method. P-E curves were measured under a temperature range of 25~150 °C. Energy storage densities and efficiencies were calculated and found to be greatly enhanced for CST with moderate Mn dopants, to be specific, 0.5% Mn demonstrated the optimized high temperature energy storage properties. The conduction relaxation behavior was investigated and the conduction activation energy was found to be sensitive to the variation of energy storage properties.

关键词： Energy storage Ceramics Manganese Dielectrics Temperature Electric breakdown Grain boundaries

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Biomemory: Phototunable Biomemory Based on Light-Mediated Charge Trap (Adv. Sci. 9/2018)

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advanced Science 2018年第9期5卷 1870051-1870051页

作者： Ziyu Lv Yan Wang Zhonghui Chen Long Sun Junjie Wang Meng Chen Zhenting Xu Qiufan Liao Li Zhou Xiaoli Chen Jieni Li Kui Zhou Ye Zhou Yu-Jia Zeng Su-Ting Han Vellaisamy A. L. Roy College of Electronic Science and Technology Shenzhen University Shenzhen 518060 P. R. China Department of Materials Science and Engineering and State Key Laboratory of Millimeter Waves City University of Hong Kong Tat Chee Avenue Kowloon Hong Kong SAR 999077 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology 122 Luoshi Road Wuhan 430070 P. R. China State Key Laboratory of Transducer Technology Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 China Institute for Advanced Study Shenzhen University Shenzhen 518060 P. R. China College of Optoelectronic Engineering Shenzhen University Shenzhen 518060 P. R. China

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Mechanical Properties and Fracture Behaviour of Multilayer Alumina Composites

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Journal of Wuhan University of technology(materials Science) 2015年第5期30卷 965-967页

作者：郑新国 ZHAO Fei 张金咏 Railway Engineering Research Institute of China Academy of Railway Science State Key Lab of Advanced Technology for Material Synthesis and Processing Wuhan University of Technology

Adopting a ceramic/polymer multilayer structure design to simulate the structure of nacre is usually believed to be an effective way to increase the toughness of ceramic composites at the expense of the material’s bending strength. However, in this study, we found that both the bending strength and the toughness could be improved simultaneously when using a certain Al2O3/Kevlar multilayer composite design compared to pure alumina samples with the same dimensions. The fracture behaviour of the Al2O3/Kevlar multilayer composite was studied to find a reason for this improvement. The results showed that the complex and asymmetrical stresses occurring in the Kevlar-reinforced layers were the main reason for the differences in fracture behaviour. We expect our results to open up new ways for the design of future high performance ceramic composites.

关键词： biomaterials alumina multilayer composite toughening

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Preparation of Nano-sized Zirconium Carbide Powders through a Novel Active Dilution Self-propagating High Temperature synthesis Method

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Journal of Wuhan University of technology(materials Science) 2015年第4期30卷 729-734页

作者：达奥运龙飞 WANG Jilin XING Weihong WANG Yang ZHANG Fan 王为民 FU Zhengyi State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Key Lab of New Processing Technology for Nonferrous Metals & Materials Ministry of Education China Guilin University of Technology

High quality nano-sized zirconium carbide （ZrC） powders were successfully fabricated via a developed chemical active dilution self-propagating high-temperature synthesis （SHS） method assisted by ball milling pretreatment process using traditional cheap zirconium dioxide powder （ZrO2）, magnesium powder （Mg） and sucrose （C12H22Oll） as raw materials. FSEM, TEM, HRTEM, SAED, XRD, FTIR and Raman, ICP- AES, laser particle size analyzer, oxygen and nitrogen analyzer, carbon/sulfur determinator and TG-DSC were employed for the characterization of the morphology, structure, chemical composition and thermal stability of the as-synthesized ZrC samples. The as-synthesized samples demonstrated high purity, low oxygen content and evenly distributed ZrC nano-powders with an average particle size of 50nm. In addition, the effects of endothermic rate and the possible chemical reaction mechanism were also discussed.

关键词： zirconium carbide ZrC self-propagating high-temperature synthesis active dilution nano-powders ball milling

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Recent advances in biological detection with magnetic nanoparticles as a useful tool

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Science China Chemistry 2015年第5期58卷 793-809页

作者： Liwei Lu Xiuyu Wang Chuanxi Xiong Li Yao State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Beijing National Laboratory for Molecular Sciences State Key Laboratory for Structural Chemistry of Unstable and Stable Species Institute of Chemistry Chinese Academy of Sciences

Magnetic nanoparticles have emerged as a powerful tool for magnetic resonance imaging, biodetection, drug delivery, and hyperthermia. This review focuses on the biological detection of magnetic nanoparticles as well as their physicochemical properties. Substantial progress in the sensitivity of detection has been made by developing variety of methods. Five applications of magnetic nanoparticles in biological detection are discussed in this review: magnetic separation, magnetic sensing, magnetic manipulation, magnetic catalysis, and signal enhancer for surface plasmon resonance(SPR). Finally, some future trends and perspectives in these research areas are outlined.

关键词： magnetic nanoparticles biological detection sensitivity methods

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Preparation of MgF_2 Translucent Ceramic by Hot Pressing Sintering

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Journal of Wuhan University of technology(materials Science) 2015年第4期30卷 720-723页

作者：彭敏红 CAO Weiping 宋金红 Center of Materials Research and Analysis Wuhan University of Technology State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology

The aim of this work was to prepare MgF2 translucent ceramic by using nanopowders as raw materials and to study its *** MgF2 nanopowders were prepared using chemical precipitation and the translucent ceramics were fabricated by hot-pressing sintering in a vacuum environment. X-ray diffraction analysis showed that the powders were homogeneous with an average particles size about 13 nm. By comparing the results of transmission electron microscopy, it could be concluded that the porous structure of precursor powders could be improved by calcination. The SEM images of MgF2 indicated that the as-prepared ceramics were well densified at 900 ℃. The photo of the ceramic sample showed that high translucence is a main breakthrough in the field of MgF2 materials preparation. For the translucent ceramic sample sintered at 900 ℃, the Viekers hardness and density were 5.55 GPa and 98.74%, respectively, and its highest transmittance with thickness of lmm reached 87% in the wavelength from 2.5 lain to 10 btm, all which made it advantageous to be a kind of infrared windows and dome materials.

关键词： MgF2 nanopowders calcination hot-pressing translucent ceramic

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