检索结果-南通市图书馆

impedance spectra of hot, dry gabbro at high temperature and pressure

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2002年第5期 79-82页

作者： WANG Duojun, LIU Congqiang, LI Heping, YI Li, SU Genli and DING Dongye( Laboratory for Study of the Earth's Interior and Geofluids, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China) Laboratory for Study of the Earth's Interior and Geofluids，Institute of Geochemistry，Chinese Academy of Sciences，Guiyang 550002，China Institute of Geochemistry，Chinese Academy of Sciences，Guiyang 550002，China

impedance spectra of hot, dry gabbro have been studied at 1.0 - 2.0GPa and 593-1173 *** experimental results indicate that complex impedance depends on frequency of altering current. impedance arcs representing grain interiors and grain boundaries conduction mechanism are displayed in the complex impedance plane. The impedance arc corresponding to grain interiors occurs over the range of 102-105 Hz, and the impedance arc corresponding to grain boundaries occurs over the range of 12 - 102 Hz. Each element of e-quivalent circuit corresponding to grain interiors is fit for complex nonlinear least square program. When garnet occurs in gabbro, the electrical conductivity of gabbro abruptly changes.

关键词： high temperature and pressure gabbro impedance spectra electrical conductivity break.

Structure and electrical properties of (1-x)BaTiO_3+(x)La_(2/3)-Sr_(1/3)MnO_3 composites

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2011年第4期24卷 315-320页

作者： Zhengyou ZHOU Yu LEI School of Materials Science and Engineering Nanchang University Nanchang 330031 China College of Vocational Education East China Jiaotong University Nanchang 330031 China

Liquid-phase sintering method was used to prepare BaTiO3 powders and the struc- ture and electrical properties of （1-x）BaTiO3-]-（x）La2/3Srl/3Mn03 （LSMO） compos- ites were investigated. The results of X-ray diffraction showed that the prepared BaTiO3 powders were pure and fine, indicating that sintering temperature was effec- tively lowered when the NaC1 sintering aid was added. X-ray diffraction patterns of （1-x）BaTiO3＋（x）La2/3Srl/3Mn03 （LSMO） composites showed that LSMO and BaTiO3 phases were coexistent and no other phases were detected. The impedance spectra showed that the resistance of grain boundaries for LSMO-doped samples was suppressed. The resistivity-temperature measurements showed that room- temperature resistivity of the composites was lowered from insulator for pure BaTiO3 ceramic to 103 ~.m for the x----0.3 sample. The sample of x_〈0.2 showed the positive temperature coefficient （PTC） effect whereas the x=0.3 sample exhibited PTC effect at temperatures below 68 ~C and then negative temperature coefficient （NTC） effect at temperatures above 68 ~C. The related mechanism has been elucidated.

关键词： Positive temperature coefficient Composite impedance spectra Resistivity

Low Temperature Preparation of Ceria Solid Solutions Doubly Doped with Rare-Earth and Alkali-Earth and Their Properties as Solid Oxide Fuel Cells

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2003年第4期21卷 461-465页

作者：任引哲蒋凯王海霞孟健苏锵 Chemistry & Environmental Science College The Key Laboratory of Rare Earth Chemistry and Physics

A series of solid electrolytes, (Ce 0.8 Ln 0.2 ) 1- x M x O 2-δ (Ln= La, Nd, Sm, Gd, M:Alkali earth), were prepared by amorphous citrate gel method. XRD patterns indicate that a pure fluorite phase is formed at 800 ℃. The electrical conductivity and the AC impedance spectra were measured. XPS spectra show that the oxygen vacancies increase owing to the MO doping, which results in the increase of the oxygen ionic transport number and conductivity. The performance of ceria based solid electrolyte is improved. The effects of rare earth and alkali earth ions on the electricity were discussed. The open circuit voltages and maximum power density of planar solid oxide fuel cell using (Ce 0.8 Sm 0.2 ) 1-0.05 Ca 0.05 O 2- δ as electrolyte are 0.86 V and 33 mW·cm -2 , respectively.

关键词： ceria solid electrolyte amorphous citrate gel method impedance spectra solid oxide fuel cell rare earths

Low temperature preparation and fuel cell properties of rare earth doped barium cerate solid electrolytes

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 1999年第3期42卷 298-304页

作者：蒋凯何志奇孟建任玉芳苏锵 Laboratory of Hare Earth Chemistry and Physics Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun China

The solid electrolytes, BaCe0.8Ln0.2O2.9(Ln: Gd, Sm, Eu), were prepared by the sol-gel method. XRD indicated that a pure orthorhombic phase was formed at 900°C. The synthesis temperature by the sol-gel method was about 600°C lower than the high temperature solid phase reaction method. The electrical conductivity and impedance spectra were measured and the conduction mechanism was studied. The grain-boundary resistance of the solid electrolyte could be reduced or eliminated by the sol-gel method. The conductivity of BaCe0.8Gd0.2O2.9 is 7.87 × 10-2 S· cm-1 at 800°C. The open-rireuit voltage of hydrogen-oxygen fuel cell using BaCe0.8Gd0.2O2.9 as electrolyte was near to 1 V and its maximum power density was 30 mW· cm-2.

关键词： BaCeO3 solid electrolyte fuel cell impedance spectra sol-gel method

Formation Characteristic of CO_2 Corrosion Product Layer of P110 Steel Investigated by SEM and Electrochemical Techniques

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2009年第4期16卷 89-94页

作者： ZHAO Guo-xian LU Xiang-hong XIANG Jian-min HAN Yong Department of Materials Science and Engineering Xi'an Shiyou University Xi'an 710065 Shaanxi China Tarim Oil Field Kuerle 841000 Xinjiang China Xi'an Maurer Petroleum Engineering Laboratory Xi'an 710065 Shaanxi China

Formation characteristic of CO2 corrosion product layer on the surface of P110 steel was investigated in simulated oilfield environment using massqoss experiment, potentiodynamic polarization curve, impedance spectroscopy, and SEM micrograph analysis. Samples of different times up to 240 h were tested during exposure. Corrosion product was primarily composed of Fe（Ca, Mg）（CO3 ）2, which was distinguished by two layers. With an increase in the exposure time, the charge transfer resistance and polarization resistance increased progressively, the uniform cor- rosion rate decreased, and the corrosion reaction was controlled by the diffusion process instead of the activation process. All phenomena were attributed to the formation of the protective corrosion product layer. More compact and lower porosity of the layer made it more difficult to transfer and diffuse through the corrosion product layer for the charges and ions. Similar results were obtained bv electrochemical test and mass-loss experiment.

关键词： CO2 corrosion P110 steel electrochemistry impedance spectra

Features of the Conductivity of the Ag₈Ge_1-xMn_xTe₆ Solid Solutions

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science and Chemical Engineering 2022年第5期10卷 16-28页

作者： Rashad Rahimov Aynur Gahramanova Durdana Arasly Almaz Halilova Ilgar Mammadov Institute of Physics of Azerbaijan National Academy of Sciences Baku Azerbaijan

Samples of Ag8Ge1-xMnxTe6 solid solutions with different manganese content (x = 0, 0.05, 0.1, 0.2) were prepared by fusing and further pressing their powders under the pressure of 0.6 GPa. In addition of Mn atoms to the Ag8GeTe6 compound leads to compression of their lattice. All p-type samples acquire a high resistance below the transition at temperatures of 180 - 220 K. The electrical conductivity of all compositions in the range of 220 - 300 K increases due to hopping mechanism, and at temperatures T > 320 K, a semiconductor characteristic is observed. By studying impedance spectra of samples, it was established that at 80 K solid solutions behave like a homogeneous dielectric material. At high temperatures and frequencies of an external electric field, a significant role of grain boundaries in conductivity was revealed. The dielectric anomaly occurring at low frequencies is also associated with an effect that manifests itself in the grain boundary.

关键词： Solid Solutions X-Ray Diffraction Hopping Conductivity Electrical Conductivity impedance spectra

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

快硬硫铝酸盐水泥净浆试样的交流阻抗研究

快硬硫铝酸盐水泥净浆试样的交流阻抗研究