Structural peculiarities of Bi,Pb-2223/Ag composites annealed in an N<Subscript>2</Subscript>-O<Subscript>2</Subscript> atmosphere

X-ray diffraction analysis, transmission and scanning electron microscopy, and electron microprobe analysis were used to study Bi,Pb-2223/Ag composites annealed in a low-oxygen atmosphere (7.5% O₂ + 92.5% N₂). The ceramics was found to be characterized by some nonuniformity in the distribution of all the components. Two structural peculiarities of the 2223 phase were found. These are the existence of atomic displacement waves, which are related to the oxygen deficiency or nitrogen substitution for oxygen, and a more intense Ag penetration into the ceramics, which results from the annealing in the O₂-N₂ atmosphere at a pressure of 10 atm. The unstable state of the lattice characterized by oxygen atomic displacement waves is due to the prolonged annealing in oxygen-depleted atmosphere. Usually, in the case of other favorable factors of the ceramics structure, the lattice instability positively affects the superconducting properties of the ceramics.     

Effect of external force fields on the domain structure of equiatomic CuAu alloy

Peculiarities of the ordered-structure formation in the equiatomic CuAu alloy, which are caused by changes in the sample dimensions and by an applied external force field, have been studied. The rate of the microstructure transformation in the ordered alloy has been found to increase with increasing thickness of the sample. It has been shown that tensile stresses applied during heat treatment can affect the growth direction of c domains and, thus, makes it possible to avoid the low-temperature cracking of the material.     

Process of faceting in nanoparticles of FCC metals: Results of simulation by the molecular-dynamics method

The process of formation of facets (faceting) in Ni, Al, and Au nanoparticles has been investigated by the molecular-dynamics method. It has been established that the surface of nanoparticles of fcc metals with attainment of a low-energy habit can be transformed via correlated displacements of atomic groups of the facet in the octahedral plane. It has been shown that such a process is similar to the surface diffusion of atomic n-mers with the activation energy depending on the facet size, and for particles with a diameter d < 3.0 nm the correlated displacement of atomic layers proves to be the dominant mechanism of faceting.     

Effect of mechanical milling on the mobility of hydrogen in the ZrTi<Subscript>2</Subscript>-H system stabilized by hydrogen: NMR data

Methods of X-ray diffraction (XRD) and nuclear magnetic resonance (NMR) were used to investigate the effect of milling on the properties of the hydrogen-stabilized compound ZrTi₂H_3.9 with the structure of the metallic sublattice of the C15 type. It has been found that the milling leads to a phase separation in the initial sample: there appears an additional phase with a structure of the TiH₂ type and an average grain size of approximately 10 nm. The mobility of hydrogen in the phase of the TiH₂ type is considerably lower than in the phase of the C15 type. An analysis of the results of measurements of rate the spin-lattice relaxation of 1H nuclei in wide ranges of temperatures (20–420 K) and resonance frequencies (14.6–90 MHz) allowed us to estimate the parameters of the hopping motion of hydrogen atoms in the phase of the C15 type. It has been established that an increase in the time of milling leads to a decrease in the mobility of hydrogen in this phase.     

The synthesis of novel fluorine-containing random polymer and application in modification of solid surfaces

The novel fluorine-containing random polymers, poly (2, 3, 4, 5, 6-pentafluorostyrene)-r-poly (4-vinyl benzocyclobutene) random copolymer was synthesized, which can effectively decrease the surface energy and provide a good corrosion protection for some metals. Additionally, textured silicon was fabricated by an optically assisted electrochemical etching process to study the effect of the random copolymer modification on the binary geometric structures of the solid surface. After modification the superhydrophobic property can easily be obtained, which show long-term stability and good superhydrophobicity in corrosive solutions over a wide pH range, including acidic and basic solutions.     

软模板法合成有序介孔材料的研究进展

有序介孔材料具有高度有序的孔道结构,较高的比表面积和较多活性位,已经广泛应用于气体吸附、催化剂和功能材料等领域。本文系统评述了软模板法制备有序介孔材料的合成路线及其组装机理,并对课题组采用软模板法组装介孔氧化钛粒子的机理进行了分析。     

乳液聚合方法研究进展

乳液聚合方法具有各方面的优点和广泛的应用范围,因此,受到人们的广泛关注。本文介绍了乳液聚合的优缺点,并着重介绍了一些新的乳液聚合方法及其原理、特点、应用以及中外最新的一些研究成果。     

关于双语教案设计的几点看法——以国际商务谈判为例

分析商务谈判课程双语教学概念存在的误区.阐述双语教育和双语教学的关系,指出商务谈判课程教案撰写中存在的问题,探讨教案撰写原则和教案撰写思维方式的转变.     

A method and integrated circuit for processing random data streams in multichannel experimental physical equipment

An asynchronous data stream processing method in multichannel experimental physical equipment is described. The conversion of an input data stream irregular in time into data synchronized with the fundamental clock frequency of the system is considered. The realization of the proposed method as part of the specialized integrated circuit manufactured by the CMOS process of the UMC Co. (Taiwan) with 0.18-μm design rules is presented. The structure, principle of operation of the microcircuit, and experimental results of its tests are described. The work is performed as a part of the CBM experiment of the new FAIR accelerating facility (GSI, Darmstadt, Germany).     

实芯焊丝拉拔过程中的热处理工艺介绍

叙述了低碳合金结构钢、不锈钢、镍基合金实芯焊丝拉拔过程中的热处理工艺选择;讨论了焊丝的热处理缺陷及防止措施。