材料期刊网

THE DETERMINATION OF THE RESIDUAL STRESS DURING THE FATIGUE CRACK EXTENDSION

X.G.Guo1) , H.R.Yang1)and T.Wu2) 1) Shenyang University , Shenyang 110044 , China. 2) Liaoning Jin sheng Construction Company , Shenyang 110044 , China.

金属学报(英文版)

The distribution law of the lateral residualstress at the welding seam is determinated by meansofcuttingthespecimen. Becausetocutthespecimencansimulateapproximatelytheex tension ofthe fatiguecrack,through measuring thestressreleased and calculating the distri bution oftheresidualstressthelaw isfound thattherateofthefatiguecrackextensionisaf fected bytheresidualstress.

关键词: crack extension , null , null

Investigations on the EPR g factors for the six-coordianted Cu2+(1) site in YBa2Cu3O6+x

International Journal of Modern Physics B

The EPR g factors g(//) and g(perpendicular to) for the six-coordinated Cu2+(1) site in YBa2Cu3O6+x are theoretically investigated from the perturbation formulas for a 3d(9) ion in tetragonally elongated octahedra. The related tetragonal crystal-field parameters Ds and Dt are determined from the superposition model and the structural data for the Cu2+(1) site, by considering the effective elongation of the oxygen octahedron due to the Jahn-Teller effect of the Cu2+ cluster. Based on the calculations, the effective elongation (= 15%) of the ligand octahedron is obtained for the signals at 100K. As for the EPR signals at room temperature, the elongation declines to merely 4%, corresponding to the smaller anisotropy Delta g (=g(//) - g(perpendicular to)). The theoretical results for the g factors are in good agreement with the observed values, and the local tetragonal distortion due to the Jahn-Teller effect is discussed.

关键词: crystal fields and spin hamiltonians;electron paramagnetic resonance;Cu2+;YBa2Cu3O6+x;single-crystals;yba2cu3o7-delta;evolution;esr

Investigations of EPR g Factors and Rhombic Distortion for the Rhombic Cu2+ Centers in K2Zn1-x Cu (x) F-4 Crystals at Low Temperature

Applied Magnetic Resonance

The electron paramagnetic resonance g factors g (i) (i = x, y, z) of two rhombic Cu2+ centers, Cu2+(II) and Cu2+(III), in K2Zn1-x Cu (x) F-4 crystals found at low temperature are calculated from the complete diagonalization (of energy matrix) method based on the cluster approach. The calculations show that the ground state wave function of the two rhombically compressed Cu2+ centers is with a small admixture of . The rhombic distortions for both Cu2+ centers are obtained from the calculations. The results are discussed.

关键词: electron-paramagnetic-resonance;atomic screening constants;hyperfine;parameters;gyromagnetic factor;spin resonance;scf functions;field;copper(ii);dependence;spectra

Investigations on the Zero-Field Splittings and the g Factor of Gd(x)Eu(1-x)Ba(2)Cu(3)O(7-delta)

Journal of Superconductivity and Novel Magnetism

The zero-field splittings (D and E) and the g factor of Gd(x)Eu(1-x)Ba(2)Cu(3)O(7-delta) are theoretically investigated from the superposition model formulas or the zero-field splittings and the approximation formula of the g factor containing the admixtures of the ground (8)S(7/2) and the excited (6)L(7/2) (L = P, D, F, G) states, respectively. Based on the studies, the impurity-ligand bond angles related to the crystalline c axis in the impurity Gd(3+) center are about 1.1 degrees smaller than those in the host Eu(3+) site of EuBa(2)Cu(3)O(7-delta). The calculated D, E, g factor and the effective magnetic moment mu(eff) show reasonable agreement with the experimental data. Particularly, the improvement for the theoretical D is achieved in the present work by considering the above angular distortion.

关键词: Crystal fields and spin Hamiltonians;EPR;Superposition model;Gd(x)Eu(1-x)Ba(2)Cu(3)O(7-delta);spin-hamiltonian parameters;gd3;superconductor;euba2cu3oy

超超临界钢G-X12CrMoWVNbN 10 1 1长时间等温热处理过程中的组织演变

胡小强 , 罗兴宏 , 李殿中

材料热处理学报 doi:10.3969/j.issn.1009-6264.2007.z1.002

本文研究了G-X12CrMoWVNbN10 1 1钢在700℃长时间等温处理过程中的组织演变.通过DTA曲线,分析得到该钢种在加热和冷却过程中的各相转变温度.采用光学显微镜、扫描电镜和能谱分析,研究不同时间等温处理后的组织.结果表明:M3C型碳化物优先在原奥氏体晶界附近析出,此后,碳化物聚集长大导致出现两相区.随着等温处理时间的增加,两相区的转变量近似以S形规律增加,基体硬度则线性降低.

关键词: 超超临界钢 , 改进型9Cr1Mo钢 , 组织演变 , 碳化物 , 等温处理

Investigations of the g factors and local structure for orthorhombic Cu2+ (1) site in fresh PrBa2Cu3O6+x powders

Condensed Matter Physics

The electron paramagnetic resonance (EPR) g factors g(x), g(y) and g(z) of the orthorhombic Cu2+ (1) site in fresh PrBa2Cu3O6+x powders are theoretically investigated using the perturbation formulas of the g factors for a 3d(9) ion under orthorhombically elongated octahedra. The local orthorhombic distortion around the Cu2+ (1) site due to the Jahn-Teller effect is described by the orthorhombic field parameters from the superposition model. The [CuO6](10-) complex is found to experience an axial elongation of about 0.04 angstrom along c axis and the relative bond length variation of about 0.09 angstrom along a and b axes of the Jahn-Teller nature. The theoretical results of the g factors based on the above local structure are in reasonable agreement with the experimental data.

关键词: crystal fields and Hamiltonians;electron paramagnetic resonance;Cu2+;PrBa2Cu3O6+x;epr;ions;crystal;spectra

强双光子吸收化合物NT-G1和NO-G1合成与性能研究

刘国华 , 杨平 , 蒋宛莉 , 郭晓稚 , 许贵宝 , 蒋雪璋 , 沈梁 , 王筱梅

功能材料

选择氮杂芴(咔唑)为π-中心,分别以三苯胺和噁二唑取代基为"枝",合成了两个强双光子吸收的氮杂芴衍生物-2,8-双(4-三苯胺乙烯基)-N-乙基氮杂芴(简称NT-G1)和2,8-双(2-(4'-乙氧基)-5-(4'-苯乙烯)-1,3,4- 噁二唑)-N-基氮杂芴(简称NO-G1),进行了核磁共振谱和质谱等表征.飞秒钛宝石激光器泵浦下,NT-G1和NO-G1溶液发出强双光子上转换荧光,且后者的双光子荧光发射截面是前者的7倍;双光子荧光法计算出NT-G1和NO-G1双光子吸收截面分别为215GM和454GM.分子构型优化表明,NT-G1分子中心"氮杂芴"所在平面与两端苯环呈螺旋桨式排布;而NO-G1分子共轭长度增大,且中心的"氮杂芴"与两端延伸的"枝"呈平面构型;从结构上看,NO-G1分子属"D-A-π-A-D"型,具有明显的pn结模式,这些都使NO-G1分子具有更好的分子内电荷转移能力,因而有较高的双光子吸收截面.

关键词: 2,8-双(4-三苯胺乙烯基)氮杂芴 , 2,8-双(2-(4'-乙氧基)-5-(4'-苯乙烯)-1,3,4- 噁二唑)-N-乙基氮杂芴 , 双光子吸收 , 双光子荧光

Calculation of EPR parameters g factors for Ce3+ ion in YBa2Cu3O6+x superconductor

International Journal of Modern Physics B

The perturbation formulae of EPR parameters g factors g(x), g(y) and g(z) for the lowest Kramers doublet of 4f(1) ion in orthorhombic symmetry are established. In these formulae, the contributions of the covalency effects, the admixture between J = 7/2 and J = 5/2 states as well as the second-order perturbation (which is not considered in the previous works) via crystal-field and orbital angular momentum interactions are all included. According to these formulae, and by using the superposition model, the g-factors g., g(y) and g(z) for Ce3+ center in YBa2CU3O6+x superconductor are calculated. The results are discussed.

关键词: YBa2Cu3O6+x;EPR;superposition model;Ce3+;crystal-field

INVESTIGATIONS ON THE g FACTORS AND THE SUPERHYPERFINE PARAMETERS FOR THE TETRAGONAL Pd(3+) CENTERS IN AgX (X = Cl, Br)

International Journal of Modern Physics B

The g factors and the superhyperfine parameters for the tetragonal Pd(3+) centers in AgX (X = Cl, Br) are theoretically investigated from the perturbation formulas of these parameters for a 4d(7) ion in tetragonally elongated octahedra In the calculations, the related molecular or coefficients and the unpaired spin densities of the ligands are determined quantitatively from the cluster approach in a uniform way. Both centers originate from substitutional Pd(3+) on Ag(+) site in AgX, with no charge compensator (silver vacancy) nearby. The [PdX(6)](3-) clusters suffer a relative elongation of 0.01 angstrom (or 0.06 angstrom) along [1 0 0] (or C(4)) axis for X = Cl (or Br) due to the Jahn-Teller effect The calculated g factors and the superhyperfine parameters based on the above Jahn-Teller elongations show good agreement with the experimental data.

关键词: Electron paramagnetic resonance;crystal and ligand fields;Pd(3+);AgCl;AgBr;transition-metal ions;epr spectroscopic investigations;electron-paramagnetic-resonance;atomic screening constants;laser-light;generation;color image-formation;silver bromide;superposition model;scf functions;agbr

Theoretical investigations of the g factors and the local structure for the trigonal Zr(3+) center in X-ray irradiated YSZ

Journal of Alloys and Compounds

The electron paramagnetic resonance (EPR) g factors g(parallel to) and gperpendicular to and the local structure for the trigonal Zr(3+) center in X-ray irradiated yttria-stabilized zirconia (YSZ) are theoretically investigated from the perturbation formulas of the g factors for a 4d(1) ion in trigonally distorted octahedra. Based on the studies, in this trigonal center (characterized as [ZrO(6)](9-) cluster associated with two oxygen vacancies V(o) along the [ 111] axis), the O(2-) ions in the ligand triangles are found to displace towards the neighbouring Vo by about 0.42 Angstrom due to the electrostatic attraction of the V(o). The above displacement is comparable with that (approximate to 0.36 Angstrom) obtained from neutron diffraction measurements and those (approximate to 0.24-0.37 Angstrom) based on the optical spectral analysis and crystal-field calculations in the previous works. Particularly, partial quenching of the spin-orbit (SO) coupling interaction (i.e., gamma(SO) approximate to 0.44) due to the dynamic Jahn-Teller effect (DJTE) and its influence on the g factors, which were ignored by the previous authors, are taken into account in the present work. The validity of the results is discussed. (C) 2004 Elsevier B.V. All rights reserved.

关键词: electron paramagnetic resonance (EPR);defect structure;crystal-fields;and spin Hamiltonian;Zr(3+);yttria-stabilized zirconia (YSZ);oxide fuel-cells;paramagnetic-resonance spectra;yttria-stabilized;zirconia;spin-orbit interaction;single-crystals;electron traps;ions;epr;fabrication;impurity