X.G. Yang
,
K. Y. Shu
,
X.B. Zhang
,
Y.Q. Lei and Q.D. Wang(Department of Materials Science and Engineering
,
Zhejiang University
,
Hangzhou 310027
,
China)W. K. Zhang(College of Applied Chemistry
,
Zhejiang University of Technology
,
Hangzhou 310014
,
China)G.L. Lu(Centre of Analysis and Mesurement
,
Hangzhou University
,
Hangzhou 310028
,
China)
金属学报(英文版)
The effect of La alloying on the crystalline characteristics, electrochemical capacity and activity of AB2 type Zr-Cr-Ni hydride electrodes was investigated. It was found that La alloying was able to shorten the activating process from 15 cycles of La-free alloy to 2 cycles, and that the main phase shifts from C14 to C15 by XRD analysis. It may be attributed to the modification of surface chemical states and change in internal microstructures. However, the cycling stability was also found to degrade severely for La-containing hydride electrode because of the collapse of its distorted lattice.
关键词:
Zr-Cr-Ni hydrogen storage alloy
,
null
,
null
Physica Status Solidi B-Basic Research
The EPR g-factors g(\\), g(perpendicular to) and hyperfine structure constants A(\\), A(perpendicular to) for a tetragonal Co2+ centre, i.e.. Co(H2O)(2)Cl-4 centre, in NH4Cl crystal are calculated from the perturbation formulas based on a cluster approach. In these formulas, the parameters related to the contributions from the configuration interaction. the covalency effect and the low-symmetry crystal field can be obtained from the optical spectra and the structural model and data of the studied system. The core polarization constant it in the calculation formulas of hyperfine constants is used as an adjustable parameter. The calculated results are in good agreement with the observed values.
关键词:
superposition model;centers;resonance;ions;cr3+
Physica Scripta
The g factors g (parallel to) and g (vertical bar) of the isolated tetragonal Cu(II)O-5 cluster in YBa2Cu3O7-delta superconductors induced and suppressed by mechanical processing are calculated from the complete diagonalization (of the energy matrix) method (CDM) and the perturbation theory method (PTM). Both methods are based on the cluster approach where in addition to the contribution of the spin-orbit parameter of the central metal ion, the contribution of ligand ion via the covalence effect is taken into account. In the calculations, the structural data of the Cu(II)O-5 cluster gained from x-ray diffraction are applied. The results from both the CDM and the PTM are similar and show reasonable agreement with the experimental values. It appears that both methods can be used to explain the EPR g factors for d(9) ions in crystals.
关键词:
electron-paramagnetic-resonance;spin-hamiltonian parameters;atomic;screening constants;temperature-dependence;crystal-field;single-crystals;gyromagnetic factor;scf functions;ions;yba2cu3o6+x
Physica Status Solidi B-Basic Research
The perturbation formulae of EPR g-factors g(i) (i = x, y, z) and hyperfine constants Ai for a 3d(7) (Co2+) ion at a rhombic octahedral site in a crystal are established from a cluster approach. In these formulae, the contributions from the covalency effect, the configuration interaction and the rhombic crystal field are considered and the parameters used in the calculation of EPR parameters. except the core polarization constant x in the calculation of Al, can be estimated from the optical spectra and the structure data of the studied system. From these formulae, the EPR parameters g(i) and A(i) for the rhombic Co2+-V-Ag centre in AgCl are reasonably explained by considering suitable rhombic distortion and so the microstructure of this rhombic centre is obtained.
关键词:
superposition model;crystals
Juliang Xu
材料科学技术(英文)
The critical pitting temperature (CPT) of 2101 lean duplex stainless steel (DSS) in 1 mol/L NaCl was investigated. Potentiostatic electrochemical noise (EN) technique coupled with scanning electron microscopy (SEM) was used to study the corrosion process of 2101 DSS at different temperatures (15, 25, 28, and 35 °C) from below CPT to above CPT. The EN data were analyzed by wavelet technique based on orthogonal db4 wavelet. The results showed that, the patterns of current noises were different at different temperatures. The characteristics of energy distribution plot (EDP) obtained from wavelet analysis technique can be used as "fingerprints" of EN signal and can be used to interpret the corrosion process. With increasing solution temperature, the
maximum relative energy defined in EDP changed from the region of crystal series coefficients with smaller scales through middle scales to larger scales, which indicated the process of initiation, propagation and growth into stable pitting of metastable pitting. The results were well confirmed by the corresponding morphologies.
关键词:
Duplex stainless steel
袁诗璞
电镀与涂饰
氯化钾镀锌液配方中,氯化钾的含量通常是200~ 250 g/L,但在生产维护时分析镀槽中的氯化钾有时高达近400 g/L.认为以EDTA滴定法及硝酸银滴定法分别测总锌与总氯,然后从总氯中减去氯化锌所占氯的量而计算出氯化锌含量的常规化验方法有一定的局限性,尤其不适用于大生产已久的镀液.介绍了控制氯化钾含量的方法:先调整pH,接着通过赫尔槽试验分析并调整锌离子浓度,然后分析并调整光亮剂及硼酸,最后通过试验确定氯化钾补加量.
关键词:
镀锌
,
氯化钾
,
分析
,
调整
,
赫尔槽试验
Pramana-Journal of Physics
By calculating the optical spectrum band positions and EPR parameters (g factors, g(parallel to), g(perpendicular to) and zero-field splitting D) by diagonalizing the complete energy matrix of 3d(8) ions in trigonal symmetry, the defect structure of Ni2+ centre in alpha-LiIO3 crystal is studied. It is found that to reach the good fits of optical and EPR data between calculation and experiment, the Ni2+ ion should shift by Delta z approximate to 0.298 angstrom along C-3-axis and the O-2-ions between the Ni2+ ion and Li+ vacancy (V-Li) should be displaced away from the V-Li by Delta x approximate to 0.097 angstrom because of the electrostatic interaction. The results are discussed.
关键词:
Optical spectra;electron paramagnetic resonance;defect structure;Ni2+;alpha-LiIO3.;field;ions;cr3+;temperature;parameters;epr;pressure;model;liio3
Shaoxiong ZHOU
材料科学技术(英文)
The discovery of the first Fe-based ferromagnetic amorphous alloy in 1966 had made an impact on conventional magnetic materials because of its unique properties. Since then, a number of amorphous magnetic materials have been successfully developed and used in a wide variety of applications. A brief review of R & D activities on amorphous soft magnetic materials in China is given from the beginning to the present in a somewhat chronological order, followed by a brief introduction to their applications on electric and electronic industries. An analysis and a prospect of Chinese market of such amorphous materials are also presented.
关键词:
Dangguo LI
金属学报(英文版)
The chemical composition and semi-conductive properties of passive film on nickel-based alloy (G3 alloy) in bicarbonate/carbonate buffer solution were investigated by Auger spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectra (EIS) and Mott-Schottky plot. AES and XPS results showed that the passive film appeared double-layer, in which the inner film was composed of nickel oxide, the mixed nickel-chromium-molybdenum-manganese oxides were the major component of the outer film. The electrochemical results revealed that the factors including frequency, potential, time, temperature and pH value can affect the semi-conductive property, the doping densities decreased with increasing potential and pH value, prolonging time, and decreasing temperature. According to the above results, it can be concluded that the film protection on the substrate enhanced with increasing potential and pH value, prolonging time, and decreasing temperature.
关键词:
Nickel-based alloy
,
俄歇分析
,
X-射线光电子能谱
,
电化学阻抗谱
,
Mott-Schottky曲线