材料期刊网

THE DEVELOPMENT OF MINOR CALIBER COMPOSITE PIPES ON CORROSIVE WEAR RESISTANT

S.H. Li , J.S.Li , S.X. Wang , Y.J. Yin and J.J. Wang Ordnance Engineering College , Shijiazhuang 050003 , China

金属学报(英文版)

The ceramic lined pipes had been produced by gravitational separation SHS method and influential factors on combustion synthesis was investigated.The experimental results showed that the ceramic lined pipes had been produced easily under condition that selecting pipes well distributed on the wall thickness ,proper preheating temperature and appropriate additive.

关键词: gravitational separation SHS method , null , null , null

Phase Transition and Phonon Spectrum of Zinc-Blende Structure ZnX (X = S, Se, Te)

Communications in Theoretical Physics

Calculations have been performed to investigate the pressure-induced solid-solid phase transitions and the mechanical stability for three zinc-blende II-VI semiconductor compounds: ZnS, ZnSe, ZnTe by ab initio plane-wave pseudopotential density functional theory (DFT). Using the generalized gradient approximation (GGA) for exchange and correlation in the scheme of Perdew-Wang 1991 (PW91), the ground state properties and equation of state are obtained, which are well consistent with the experimental data available and other calculations. On the basis of the forth-order Birch-Murnaghan equation of states, the transition pressures P(t) are determined through the analysis of enthalpy variation with pressure. A linear-response approach is used to calculate the frequencies of the phonon dispersion. Finally, by the calculations of phonon frequencies, some thermodynamic properties such as the vibrational contribution to the Helmholtz free energy (F), enthalpy (H), entropy (S), and the heat capacity (C(V)) are also successfully obtained

关键词: phase transition;elasticity;phonon dispersion;order elastic constants;ab-initio calculations;high-pressure phase;optical-properties;electronic-structure;molecular-dynamics;crystal-structure;absorption-edge;zinc selenide;znte

On the EPR parameters of divalent cobalt in ZnX (X = S, Se, Te) and CdTe

Zeitschrift Fur Naturforschung Section a-a Journal of Physical Sciences

The electron paramagnetic resonance (EPR) parameters g and the hyperfine structure constants A of CO2+ in ZnX (X = S, Se, Te) and CdTe are studied, using the perturbation formulas of the EPR parameters for a 3d(7) ion in tetrahedra based on two mechanism models. In these formulas, both the contributions from the conventional crystal-field (CF) mechanism and those from the charge-transfer (CT) mechanism are taken into account. According to the investigations, the sign of the g-shift DeltagCT from the CT mechanism is the same as DeltagCF from the CF mechanism, whereas the contributions to the A value from the CF and CT mechanisms have opposite signs. Particularly, the contributions to the EPR parameters from the CT mechanism increase rapidly with increase of the spin-orbit coupling coefficient of the ligand and the covalency effect of the systems, i.e. S2- < Se2- < Te2-.

关键词: crystal-fields and Spin Hamiltonians;EPR;Co2+;ZnX (X = S, Se, Te);CdTe;atomic screening constants;scf functions;field theory;cr2+ ion;spectra;znse;complexes;crystal;liyf4;znte

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

PbX(X=S,Se)纳米结构材料的制备方法

危兆玲 , 李天保 , 赵君芙 , 梁建 , 马淑芳 , 许并社

材料导报

PbX(X=S,Se)纳米结构材料因其良好的光电性能,在太阳能电池等方面有着较好的应用前景,目前已成为半导体领域的研究热点.概括和总结了几种制备PbX纳米材料的经典和新型方法,其中包括水热法、溶剂热法、化学气相沉积法、中孔材料模板法、熔盐籽晶法、纳米晶的取向附属物法和微波法等,并分析和讨论了各方法的特点及对应产物的特征.

关键词: PbS , PbSe , 制备方法 , 纳米结构

Theoretical investigation of the spin Hamiltonian parameters and local structure and their concentration dependences for Cd(1-x)Mn(x)S quantum dots

Physica Scripta

The spin Hamiltonian parameters (zero-field splitting D, g factors and hyperfine structure constants) and local structure as well as their concentration dependences for Cd(1-x)Mn(x)S quantum dots are theoretically investigated from the perturbation formulae of these parameters for a 3d(5) ion under trigonally distorted tetrahedra. The impurity Mn(2+) is found not to occupy exactly the host Cd(2+) site in the CdS quantum dots but to experience an inward displacement 0.041 angstrom towards the ligand triangle along the C(3)-axis because of the size mismatching substitution and the internal stress. As compared with bulk CdS : Mn(2+), the larger impurity displacement and stronger Mn(2+) 3d-3s orbital admixture in the Cd(1-x)Mn(x)S quantum dots suitably account for the higher zero-field splitting and hyperfine structure constant, respectively. The impurity axial displacement and the Mn(2+) 3d-3s orbital admixture in the Cd(1-x)Mn(x)S quantum dots may exhibit an approximately cubic increase with increasing the Mn concentration x from 0.001 to 0.15.

关键词: electron-paramagnetic-resonance;transition-metal impurities;atomic;screening constants;optical-properties;defect structures;scf;functions;crystals;ions;nanocrystals;semiconductor

显微组织对X65～X70管线钢抗H2S性能的影响

张雁 , 蔡庆伍 , 谢广宇

腐蚀学报（英文）

通过扫描电镜（SEM）、透射电镜（TEM）等方法，研究了X65～X70级别管线钢在饱和H2S溶液中的氢致开裂行为，及不同显微组织、位错与析出对氢致开裂（HIC）的作用.结果表明：组织均匀的珠光体/铁素体型X65管线钢和铁素体/针状铁素体型X70管线钢均具有良好的抗H2S腐蚀性能；带状组织是裂纹萌生和扩展的主要途径；合金元素的弥散析出作用可以提高管线钢的抗硫化氢腐蚀性能.

关键词: 管线钢 , null , null

显微组织对X65～X70管线钢抗H2S性能的影响

张雁 , 蔡庆伍 , 谢广宇

腐蚀学报（英文） doi:10.3969/j.issn.1002-6495.2007.06.004

通过扫描电镜(SEM)、透射电镜(TEM)等方法,研究了X65～X70级别管线钢在饱和H2S溶液中的氢致开裂行为,及不同显微组织、位错与析出对氢致开裂(HIC)的作用.结果表明:组织均匀的珠光体/铁素体型X65管线钢和铁素体/针状铁素体型X70管线钢均具有良好的抗H2S腐蚀性能;带状组织是裂纹萌生和扩展的主要途径;合金元素的弥散析出作用可以提高管线钢的抗硫化氢腐蚀性能.

关键词: 管线钢 , 显微组织 , 带状组织 , 氢致开裂(HIC) , 硫化氢(H2S)

THEORETICAL STUDIES ON THE GYROMAGNETIC FACTORS FOR Fe(3+) IN ZnX (X = O, S, Se, Te)

Modern Physics Letters B

The gyromagnetic factors for Fe(3+) in ZnX (X = O, S, Se, Te) are theoretically studied from the perturbation formula of the g-factor for a 3d(5) ion in tetrahedra based on inclusion of both the crystal-field and the charge-transfer contributions. The related model parameters in the calculations are determined from the cluster approach in a uniform way. The g-shift Delta g (-g - g(s), where g(s) approximate to 2.0023 is the spin-only value) from the charge-transfer contributions is opposite (positive) in sign and much larger in magnitude as compared with that from the crystal-field ones. The importance of the charge-transfer contributions increases rapidly with increasing the covalency and the spin-orbit coupling coefficient of the ligand and thus exhibits the order of O(2-) < S(2-)

关键词: Crystal-fields and spin Hamiltonians;electron paramagnetic resonance;(EPR);Fe(3+);ZnX (X = O, S, Se, Te);spin-hamiltonian parameters;atomic screening constants;magnetic;semiconductor;paramagnetic resonance;electronic states;optical;spectra;local-structure;scf functions;ferromagnetism;impurities

国产X80管线钢的H2S应力腐蚀开裂行为

奚运涛 , 刘道新 , 蔡杭平 , 樊明峰 , 鲜宁

腐蚀学报（英文）

采用三点弯曲加载法，研究了国产X80管线钢及其焊接接头的抗H2S环境应力腐蚀开裂（SSCC）行为.结果表明，热影响区（HAZ）对应力腐蚀开裂最为敏感，主要是HAZ组织不均匀、晶粒粗大、硬度大，易引起局部腐蚀，从而导致该区SSCC敏感性高。母材的纵向和横向取样对H2S应力腐蚀不敏感，薄壁管材较厚壁管材有更好的H2S环境应力腐蚀抗力. 

关键词: X80钢 , null , null