材料期刊网

ELECTROANALYTICAL APPLICATIONS OF CARBOXYL-MODIFIED CARBON NANOTUBE FILM ELECTRODES

C.G.Hu , W.L.Wang , K.J.Liao , W.Zhu

金属学报(英文版)

The electrochemical behavior of a carboxyl-modified carbon nanotube films was inves-tigated to explore its possibility in electroanalytical applicaton. Cyclic voltammetry of quinone was conducted in 1mol/L Na2SO4, which showed a stable, quasi-reversible voltammetric response for quinone / hydroquinone, and the anodic and the cathodic peak potentials were 0.657V and -0.029V (vs. SCE) at a scan rate of 0.1V.s^-1, re-spectively. Both anodic and cathodic peak currents depended linearly on the square root of the scan rate over the range of 0.01-0.5V.s^-1, which suggested that the process of the electrode reactions was diffusion-controlled. Carboxyl-modified carbon nanotube electrodes made it possible to determine low level of dopamine selectively in the pres-ence of a large excess of ascorbic acid in acidic media using derivative voltammetry.The results obtained were discussed in details. This work demonstrates the potential of carboxyl-modified carbon nanotube electrodes for electroanalytical applications.

关键词: carbon nanotube , null , null

EFFECT OF ANNEALING TREATMENT ON THE STRUCTURE OF CdS FILMS

G.B.Liu , W.L.Wang , C.G.Hu , K.J.Liao , Q.Feng , L.H.Feng

金属学报(英文版)

The effect of annealing treatment on the structure of CdS films was investigated.The cadmium sulfide thin films were prepared by chemical bath deposition, and were annealed at nitrogen atmosphere at different temperatures. The films were charac-terized by SEM and XPS (X-ray photoelectron spectroscopy). X-ray photoelectron spectroscopy was used to examine the chemical states on the CdS films surface. It was found that thermal annealing could produce large grains of CdS thin films, remove the air contamination and reduce the oxygen content on the CdS films surface. Therefore,the CdS films changed more uniform and smoother surface after thermal annealing.

关键词: XPS , null , null

ELECTROCHEMICAL INVESTIGATION ON CARBON NANOTUBE FILM WITH DIFFERENT PRETREATMENTS

C.G.Hu , W.L.Wang , W.Zhu

金属学报(英文版)

Wide potential windows were found at carbon nanotube film electrodes in neutral solutions after being treated with nitric acid and mixed acid. Electrochemical re-versibility was investigated at carbon nanotube films with different pretreatments for ferri/ferrocyanide and quinone /hydroquinone. Carbon nanotube film electrodes pre-sented quasi-reversible electrochemical behavior for both electrolytes. In the range of scan rate, carbon nanotube film electrodes treated with acids showed heterogeneous electron-transfer properties, which was mainly controlled by its electron state density on the surface of the film. On the whole, the carbon nanotube electrode with nitric acid treatment presented the best electrochemical behaviors, so we chose it as an analytical electrode to determine the trace compound in dilute solution. The results demonstrated that this new electrode material exhibits superior performance characteristics for the detection of azide anion.

关键词: carbon nanotubes , null , null

INFLUENCES OF DENSITY AND DIMENSION OF CARBON NANOTUBES ON THEIR FIELD EMISSION

Y.B.Zhu , W.L.Wang , C.G.Hu

金属学报(英文版)

The influences of density and dimension of carbon nanotubes on their electron emis-sion from arrays are studied. The tip electric field of nanotubes, electric field enhance-ment factor, and optimum nanotube density are expressed by analytic equations. The theoretical analyses show that the field enhancement factor is sensitive to nanotube density, and can be sharply improved at a specific and optimum density. Some exper-iments have demonstrated these. Owning to electrostatic screening effect, the length of carbon nanotubes has little effect on their emission. A uniformly-distributed carbon nanotube array model is set up, and applied to analysis of carbon nanotube arrays.The results obtained here are in good agreement with the experimental data.

关键词: carbon nanotube array , null , null

Two-step magnetization in a spin-chain system on the triangular lattice: Wang-Landau simulation

Physical Review B

The Wang-Landau algorithm is used to study the thermodynamic and magnetic properties of triangular spin-chain system based on two-dimensional Ising model in order to understand the magnetic-order dynamics in Ca(3)Co(2)O(6) compound. The calculated results demonstrate that the equilibrium state of the rigid spins produces the two-step magnetization curve at low temperature even when the random-exchange term is considered. This work indicates that the four-step magnetization behavior observed experimentally must be due to the nonequilibrium magnetization.

关键词: calcium compounds;exchange interactions (electron);Ising model;magnetisation;thermodynamics;one-dimensional ca3co2o6;density-of-states;compound ca3co2o6;phase-diagram;proteins;crystal

试棒的w_0/l_0值对Zn-5%Al合金超塑性m-δ关系的影响

刘勤 , 裔式珙

材料研究学报

在250℃以■=0.025min~(-1)测到的Zn-5%Al 合金的超塑性m-δ曲线均属式。w_0/l_0值加大使m_0,m_L 和δ_F 值增大,但对δ_L 和m_F 值无大影响。试样厚度的加大(由1增大到2mm)仅使δ_L 和δ_F 值增大,考虑w_0/l_0比值的影响,C_3~((m_0-m_L))-(m_L=m_(mas))型C.L.m-δ方程式规划为:或其中,m′_0(W_0/l_0)=m_0,m′_0>m_0;m′_L(w_0/l_0)=m_L,m′_L>m。w_0/l_0=0.15—0.39。当w_O/l_0=1时,缺口效应消失,δ(或δ_F)值为最大。

关键词: Zn-5%Al合金 , mechanics of superplasticity , C.L.m-δequation

压力对L12-Co3(Al,W)化合物弹性性能与电子结构的影响

姚传生 , 陈铮 , 杜秀娟

稀有金属

基于密度泛函理论,采用第一性原理赝势平面波方法计算了不同压力下L12-Co3(Al,W)化合物的弹性性质与电子结构.计算得到零压力下的点阵常数a0与实验值和理论值相符,计算结果表明:在0～45 GPa压力范围内,L12-Co3(Al,W)化合物的弹性常数Cq (CH、C12、C44)与压力满足三阶多项式关系,体模量B、剪切模量G、本征塑性、断裂韧性随压力的增强而增加;通过引入总化学键重叠布局数,定量的计算了金属间化合物的共价键性能,结果显示压力的增加会不断增强L12-Co3(Al,W)化合物中的共价键强度;电荷差分密度分析表明,随着压力的增加,W原子得到电子,A1原子失去电子,Co-Co、Co-W原子间电荷密度明显增强,表现出更强的键合作用.

关键词: 密度泛函理论 , 弹性性能 , 电子结构 , 压力 , L12-Co3(Al,W)化合物

Ion sputter erosion in metallic glass-A response to "Comment on: Homogeneity of Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass" by L-Y. Chen, Y-W. Zeng, Q-P. Cao, B-J. Park, Y-M. Chen, K. Hono, U. Vainio, Z-L. Zhang, U. Kaiser, X-D. Wang, and J-Z Jiang J. Mater. Res. 24, 3116 (2009)

Journal of Materials Research

The morphology of the dark and bright regions observed by transmission electron microscopy for the Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass strongly depends on the ion beam parameters used for ion milling. This indicates that the ion beam could introduce surface fluctuation to metallic glasses during ion milling.

关键词: room-temperature

A comparison of the ideal strength between L1(2)Co(3)(Al,W) and Ni(3)Al under tension and shear from first-principles calculations

Applied Physics Letters

The ideal strengths of L1(2)Co(3)(Al,W) in comparison with Ni(3)Al are investigated using the first-principles method. Results for the stress-strain relationships, ideal tensile and shear strengths are presented. The calculated elastic properties agree well with the experimental observations. Co(3)(Al,W) is found to have larger moduli and higher strengths, but less ductile than Ni(3)Al. The electronic structures indicate the directional covalentlike Co-W bonding through d-d hybridization is the origin of excellent mechanical properties of Co(3)(Al,W).

关键词: ab initio calculations;aluminium alloys;cobalt alloys;ductility;elastic moduli;electronic structure;nickel alloys;shear strength;stress-strain relations;tungsten alloys;w-base alloys

316L不锈钢Ni-W-P非晶态化学镀层的耐腐蚀性能

郑志军 , 赵可昕 , 高岩

材料保护

为了弄清316L不锈钢Ni-W-P非晶态化学镀层的耐腐蚀性能,以模拟人工汗液和5.0%H2SO4溶液为腐蚀介质进行了阳极极化试验.结果发现,镀层厚度超过10μm时:(1)Ni-W-P非晶态化学镀层的耐蚀性能与316L不锈钢基本相当;(2)在前48时,Ni-W-P非晶态化学镀层耐汗液的抗变色能力也与316L不锈钢相近,但随着浸泡时间的延长,抗变色能力较316L不锈钢差.

关键词: 化学镀 , Ni-W-P非晶态镀层 , 不锈钢 , 耐腐蚀性能