Acta Chimica Sinica
Passive film formed on 304 stainless steel in 2.5 mol/L H2SO4 solution by using alternating voltage (A. V.) passivation have been investigated by measuring capacitance and photoelectrochemical parameters. The investigation of the effect of measure frequency on the slope of Mott-Schottky curve has been carried out. The photoelectrochemical measurements were consistent with the capacitance measurement. Analysis of the experimental results showed that the passive film formed 304 stainless steel by using A. V. passivation exhibits semiconducting properties. Using the simple model of semiconductor rather than the multi-donor level model can explain satisfactorily the semiconducting behavior of the film formed on 304 stainless steel by using A.V. passivation.
关键词:
A. V. passivation;passive film;semiconducting properties;stainless;steel;model;electrodes
Journal of Physics and Chemistry of Solids
The tetragonal distortion for the tetragonal V2+-V-M center in KBr:V2+ crystal is estimated by analyzing its EPR data from two theoretical models, one is the two spin-orbit (S.O.) parameter model where the contributions to EPR parameters from both the S.O. coupling of the central metal ion and that of the ligands are considered and another is the conventional one-S.O.-parameter model where only the contribution from the S.O. coupling of the central metal ion is included. The result from the two-S.O.-parameter model is more than ten times that of the one-S.O.-parameter model. The reasonableness of the former is discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.
关键词:
inorganic compounds;crystal fields;defects;electron paramagnetic;resonance (EPR);epr parameters;transition;ions
Journal of Physics-Condensed Matter
We investigated the stable (0001) surfaces of M(2)AlC (M = Ti, V and Cr) using the first-principles plane-wave pseudopotential total energy method. Four possible (0001) terminations were considered by breaking the M-Al and M-C bonds. The corresponding surface energies were calculated and compared. The Al-and M(C)-terminated (0001) surfaces demonstrated better stability than the C- and M(Al)-terminated surfaces by their much lower surface energies. In addition, the stability of surfaces was predicted under various chemical environments as a function of chemical potentials. We further investigated the character of surface relaxations. The electronic structures of the stable Al- and M(C)-terminated surfaces were analyzed.
关键词:
ab-initio calculations;ti3sic2 thin-films;electronic-structure;elastic stiffness;al;deposition;cr2alc;simulation;adhesion;solids
Journal of Physics and Chemistry of Solids
In this paper, the high-order perturbation formulae of zero-field splitting D, E and g factors g(x), g(y), and g(z) for d(3) ions in rhombic symmetry are established by using a two spin-orbit (S.O.) parameter model in which the contributions due to both the S.O. coupling of the central d(3) ions and that of the ligands are considered. Based on these formulae, the local structural parameters of the rhombic defect centers V2+-V-M (i.e, the V2+ ion and a host metal ion vacancy V-M) in MCl:V2+ (M = Li, Na) crystals are estimated by calculating their EPR parameters. The results are discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.
关键词:
inorganic compounds;crystal fields;defects;electron paramagnetic;resonance (EPR);ions
Physica Status Solidi B-Basic Research
The high-order perturbation formulas of zero-field splitting D and gyromagnetic factors g(parallel to) and g(perpendicular to) for 3d(3) ions in tetragonal symmetry are established by using a two-spin-orbit(SO)-parameter model where the contributions to these EPR parameters from both the SO coupling of the central 3d(3) ions and that of the ligands are considered. From these formulas, the local structural parameters for the tetragonal V2+-V-M centers in MCl:V2+ (M = Na, K, Rb) crystals are estimated from the EPR data. The results are compared with those obtained from the conventional one-SO-parameter model where only the contribution of the SO coupling of central 3d(3) ions is included. The reasonableness of the results based on the two-SO-parameter model is discussed.
关键词:
ions
Journal of Magnetism and Magnetic Materials
Phase constitution and magnetic properties of Nd10Fe76B4M10 and Nd10Fe76B2M12 (M = Fe,Ti,V,Cr, Mn,Co and Al) alloys prepared by mechanical alloying and subsequent annealing have been systematically studied. It is found that the components of phases in the alloys critically depend on the additive transition metals M. In all the alloys, only the addition of Ti give significant enhancement to the permanent-magnetic properties. The increase of the Curie temperature in the Ti-doped alloys with an excessively low B content implies that part of the Ti atoms may occupy crystalline sites other than the Fe sites. In all the M additive alloys, with increasing content of the additive elements, the quantity of 1:7 phase increases and that of Nd2Fe14B-type phase decreases, (C) 2000 Elsevier Science B.V. All rights reserved.
关键词:
phase constitution;structure;magnetic properties;alloys;mechanical;alloying;nd;coercivity
葛红卫
,
王新华
,
张琰
,
李慧
,
陈立新
,
李寿权
,
严密
,
陈长聘
功能材料
为改善Ti(Cr-Mn)2 AB2型合金的储氢性能,采用A侧过化学计量和过渡金属部分替代Mn进行多元合金化,系统研究了Tix(Cr-Mn-M)2(x=1.0,1.1;M=V、Fe、Ni、Cu)合金的储氢性能.研究结果表明,V、Fe、Ni、Cu部分替代Mn进行多元合金化后,合金主相仍保持C14(MgZn2)型Laves相,合金晶胞体积增大.合金化元素部分替代Mn后合金的活化性能得到明显改善,合金吸放氢量增大,吸放氢压力滞后减小.除Fe使合金放氢平台压力有所升高外,其余合金化元素均使合金的吸放氢平衡压力有不同程度的降低,这是由于合金的晶胞体积增大所致.在所形成的合金中,以Ti1.1Cr1.2Mn0.5CuO0.3的综合性能最好,其室温下吸放氢量分别达到1.95%和1.72 9,6(质量分数).采用该合金与自制的轻质高压储氢容器(工作压力为40MPa)复合组成金属氢化物复合式高压储氢器,对其储氢密度的计算结果表明,当储氢合金的填充量(体积分数)达到0.20时,该复合式储氢器总的体积储氢密度将提高57%.
关键词:
储氢合金
,
金属氢化物
,
储氢容器
,
高压氢
