崔玉虹
,
冯玉杰
,
刘峻峰
,
邓斐今
材料研究学报
采用高温热氧化方法制备了含Mn中间层的钛基二氧化锡电催化电极Ti/Mn/SnO$_{2}$.
采用SEM、EDX以及XPS等检测方法对电极表面涂层的形貌、元素组成及元素化学态进行了分析,
研究了所制备Ti/Mn/SnO$_{2}$电极电催化氧化降解苯酚的性能. 结果表明,
Mn中间层的引入降低了电极对苯酚的电催化降解活性, 使电极的使用稳定性大为提高.
含Mn中间层的存在, 可防止电化学反应过程中析出的氧向基体的扩散,
离子对Mn$^{2+}$/Mn$^{4+}$与Sn$^{2+}$/Sn$^{4+}$的存在改变了
SnO$_{2}$电极表面催化剂的组成和结构, 导致电极性能变化.
关键词:
无机非金属材料
,
tin dioxide electrode
,
inter-layer
,
phenol
Journal of Physics-Condensed Matter
Considering the inter-site electron-electron interaction, we investigate the ground state and spin-wave excitation of a theoretical model proposed for quasi-one-dimensional pi-conjugated organic polymer ferromagnets. Within mean-field theory, the ground state of the system is shown to be a high-spin ferromagnetic state due to the topological structure of the system. By employing the random-phase approximation (RPA), the spin-wave excitation spectrum is obtained. It is found that the acoustic spin-wave mode displays the feature of the ferromagnetic magnon, and the inter-sire electron-electron interaction has influence on it. With the increase of inter-site electron-electron interaction, the high-spin ferromagnetic ground state of the system will be unstable.
关键词:
hubbard-model;ferromagnet;polyacetylene
Journal of Physics-Condensed Matter
Ag-doped La0.67Sr0.33MnO3 thin films with various Ag concentrations were deposited on (001) LaAlO3 substrates at 400degreesC by using a dual-beam pulsed-laser deposition system. The Ag-doped films show polycrystalline structure with epitaxial c-axis columns. These columns were composed of closely arranged polyhedra of size 10-15 nm, resulting from the enhanced stress-induced grain boundary diffusion. In the case of heavy doping, tiny separated Ag crystals were observed at grain boundaries. Due to the interaction between the two laser-induced plumes, the Ag precipitation also helped to form anomalous clusters consisting of nano-sized grains and amorphous phase. By adjusting the deposition conditions carefully, we can tailor the microstructure of the film and correspondingly alter the resistivity and the inter-grain magnetoresistance of the Ag-doped films. Theoretical simulation led to results consistent with the microstructure observations and the magnetoresistance measurements.
关键词:
low-field magnetoresistance;pulsed-laser deposition;manganites;ablation;growth
Modern Physics Letters B
The pyroelectric and phase transition properties of a finite alternating ferroelectric superlattice with three surface layers are studied on the basis of the transverse Ising model by using the mean field approximation. The temperature-dependence of the polarization and pyroelectric coefficient of the superlattice with various inter-layer exchange interaction constants are given. The profiles of the polarization as well as the pyroelectric coefficient of the superlattice are shown. By taking into account the effects of the exchange interaction and transverse field parameters on the phase diagrams,we find that the phase transition properties of the superlattice are sensitive to the changes of transverse Ising model parameters.
关键词:
Pyroelectric;phase transition;Ising model;transverse ising-model;long-range interactions;square lattice;thin-films;diagrams
XIA Lifang MA Xinxin Harbin Institute of Technology
,
Harbin
,
China
金属学报(英文版)
This paper deals with the cause of intergranular fracture occurred in the retained austenitic region in plasma carburized layer.The results show that the presence of retained austenite, which has a good effect on the impact toughness,has no relation to this embrittlement.Analy- sis by Auger electron spectroscopy shows that the impurities S and P segregate at the grain boundaries is the main reason of the intergranular embrittlement in carburized layer. However,the segregation of P and S can be removed by reheating and quenching treatment.
关键词:
plasma carburizing
,
null
,
null
,
null
Journal of Physics-Condensed Matter
By employing retarded Green functions, the spin-wave spectrum and the layer-sublatticc magnetization in Heisenberg ferrimagnetic three-layer superlattices and three-layer systems are calculated within the framework of the linear spin-wave approximation. The effects of the interlayer exchange constants and the intralayer exchange constants on the magnetic properties of the two systems are compared with those for the corresponding three-sublattice bulk ferrimagnets. It is found that all the differences between the magnetic properties of these systems originate from the differences between the exchange couplings in the three dimensions of the systems. The quantum correlations, such as the competition, cancellation, and transmission of the effects of the exchange couplings, are important for the magnetic properties of the systems. The asymmetry of the systems plays an important role in the zero-point quantum fluctuations and, correspondingly, in the layer-sublattice magnetizations of the layers.
关键词:
spin-waves;ferrimagnets;3-sublattice;ferromagnet;layers;modes
Acta Materialia
A graded microstructure was produced in the surface layer of a pure Cu sample by means of surface mechanical attrition treatment (SMAT) [Wang K, Tao NR, Liu G, Lu J, Lu K. Acta Mater 2006;54:5281.]. The diffusion behavior of (63)Ni in such a surface layer was investigated by the radiotracer technique at temperatures <438 K. It is shown that the effective diffusivity in the top 10 mu m surface layer is more than 2 orders of magnitude higher than that along conventional high-angle grain boundaries (HAGB) in Cu of similar purity. The diffusion rate increases gradually with increasing depth up to 30-50 mu m, and then decreases with further increasing depth. The enhanced diffusivities reveal higher-energy states of various interfaces in the SMAT surface layer. The excess free energy of HAGB in this layer is estimated to be similar to 30% higher than that of conventional grain boundaries. An apparent retardation of the effective diffusion rate in the top 25 mu m surface layer is induced by tracer leakage into numerous twin-boundary-like interfaces, while the gradual decrease in interface excess free energy correlates with the observed decrease in diffusivity in the subsurface layer at depths exceeding 50 mu m. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
关键词:
Nanostructured material;Surface mechanical attrition treatment;Diffusion;Grain boundaries;Twin boundaries;grain-boundary diffusion;mechanical attrition treatment;severe;plastic-deformation;nanocrystalline copper;self-diffusion;nickel;alloys;bulk;temperatures;segregation
YU Zhenjiang
,
YANG Dequan
,
XIE Xie
,
YAN Rongxin
,
FAN Chuizhen
,
Lanzhou Institue of Physics
,
Ministry of Aeronautical Industry
,
Lanzhou
,
China
金属学报(英文版)
The carbon layers on implanted steel surface have been studied by means of Auger spectra. It is shown that the thickness of the carbon layer is proportional to the dose of implanted ions. By comparison with the results of friction and wear tests, the friction coefficient is smaller than 0.20 at the first part of the friction coefficient curve. It is considered that the graphitic carbon layer on the top of steel is helpful to reducing the surface friction coefficient of steel.
关键词:
nitrogen ion implantation
,
null
,
null
,
null
