XPS研究Nd表面氧化物的生长过程

用X射线光电子能谱(XPS)研究新鲜Nd表面在不同氧气和空气进气量的情况下,表面氧化物的生长过程.发现氧化层由氧化物、氢氧化物及表面化学吸附水三种成分,这三种成分的增加与进气量都存在正比对数关系,氧化物和吸附水在一定进气量后趋于饱和,而氢氧化物持续不断增加,最终氢氧化物占据主要地位. 关键词： X射线光电子能谱(XPS) Nd 氧化     

非谐环盘及变幅杆组成的变幅器动力学特性研究

为了解决齿轮超声加工振动系统的设计问题,将齿轮简化为环盘,根据环盘及变幅杆的力耦合条件、边界条件及动力学方程,推导了非谐环盘及变幅杆组成的变幅器的频率方程,并利用其设计了变幅器,实验证明:变幅器的谐振频率与理论设计结果基本一致。该理论方法使变幅器由全谐振设计拓展到非谐振设计。     

First integrals and analytical solutions of the nonlinear fin problem with temperature-dependent thermal conductivity and heat transfer coefficient

Fin materials can be observed in a variety of engineering applications. They are used to ease the dissipation of heat from a heated wall to the surrounding environment. In this work, we consider a nonlinear fin problem with temperature-dependent thermal conductivity and heat transfer coefficient. The equation(s) under study are highly nonlinear. Both the thermal conductivity and the heat transfer coefficient are given as arbitrary functions of temperature. Firstly, we consider the Lie group analysis for different cases of thermal conductivity and the heat transfer coefficients. These classifications are obtained from the Lie group analysis. Then, the first integrals of the nonlinear straight fin problem are constructed by three methods, namely, Noether’s classical method, partial Noether approach and Ibragimov’s nonlocal conservation method. Some exact analytical solutions are also constructed. The obtained result is also compared with the result obtained by other methods.     

A Novel Divalent Ytterbium Complex Supported by a Bridged Diamide Ligand： Synthesis and Structure of [{Me2Si（NPh ）2Yb（THF）2}（μ3-CI）（μ4-CI）{Li（TH F） }2]2·2THF

The reaction of anhydrous YbCl3 with 1 equiv, of Li2Me2Si（NPh）2 in THF, after workup, yielded a ytterbium（Ⅲ） chloride [{Me2Si（NPh）2Yb}（μ2-CI）（TMEDA）]2·3PhMe （1） （TMEDA=tetramethylethanediamine）. The same reaction followed by treatment with Na-K alloy afforded a new ytterbium（H） complex supported by a bridged diamide with four coordinated LiC1 molecules, [{Me2Si（NPh）2Yb（THF）2}（μ3-CI）（μ4-CI）{Li（THF）}2]2·2THF （2） in high yield. Both complexes were structurally characterized by X-ray analysis to be dimers. Complex 1 was a chlorine-bridged dimer with ytterbium in a distorted octahedral geometry. In complex 2 two [Me2Si（NPh）2Yb（THF）2]- （μ3-CI）[Li（THF）]2 moieties were connected with each other by two μ4-CI bridges to form a ＂chair-form＂ framework.     

Induced absorption in yttrium aluminium perovskite crystals irradiated by 12C and 235U ions

The present work is devoted to investigation of optical absorption in pure and neodymium-doped YAlO₃ (YAP) single crystals in the spectral range 0.2–1.1 μm induced by the influence of ¹²C ions irradiation with energy 4.50 MeV/u (MeV per nucleon) and a fluence 2 × 10⁹ cm^?2 or of ²³⁵U ion irradiation with energy 9.35 MeV/u and a fluence 5 × 10¹¹ cm^?2. The induced absorption in the case of ¹²C ions irradiation is caused by recharging of point growth defects and impurities under the radiation influence. After irradiation by ²³⁵U ions with fluence 5 × 10¹¹ cm^?2 the strong absorption rise is probably caused by contribution of the lattice destruction as a result of heavy ion bombardment.     

Anisotropy of Long-term Resistivity Relaxations Induced in p -(0 0 1)GaAs/Al 0.5 Ga 0.5 As by Uniaxial Stress

Anisotropy of the piezoresistance relaxations has been observed in p -(0 0 1)GaAs/Al 0.5 Ga 0.5 As heterostructures. The character of relaxation process depends on the direction of the applied uniaxial compression: after loading along [1 m 1 0] direction the specimen resistance relaxes down to the lower magnitude while after loading along [1 1 0] direction it relaxes up to the higher magnitude. Shubnikov-de Haas oscillations and Hall effect measurements indicate that variation of the carrier concentration j N in the quantum well during relaxation processes has different signs for uniaxial compression along [1 m 1 0] and [1 1 0] directions and correlates with the corresponding change of the resistance. The piezoelectric field that in GaAs can reach the magnitude E =1.152 2 10 6 V/m at uniaxial stress P =1 kbar along d 1 1 0 ¢ directions is supposed to be responsible for the metastable state after loading (unloading) and redistribution of carriers during the relaxation process.     

星形聚合物结构的统计分析

本文用概率统计方法对偶联型星形聚合物的结构进行了系统理论分析,得到了偶联产物的分子量分布、平均分子量、平均支化度等重要结构参数与偶联剂官能度、偶联度以及起始活性聚合物分布的定量关系式。同时,文中还讨论了多官能度引发聚合反应的情况,结果表明,这类反应产物的分子量分布,可作为偶联星形聚合物分子量分布一般关系式的特例处理。     

Effect of substituent in para-substituted anilines on the isomerization rate of 5-vinylbicyclo[2,2,1]hept-2-ene catalyzed by anilinepentacarbonyliron complexes

The isomerization kinetics of 5-vinylbicyclo [2,2,1]-hept-1ene to 5-enthylidenbicyclo [2,2,1] hept-2-ene in the presence of iron pentacarbonyl and parasubstituted anilines has been investigated. The kinetic data correlate with -constants of the substitutes according to Jaffe.

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5- [2,2,1]-2- 5- [2,2,1] -2- - . - .

     

Oxoalkoxides—True precursors of complex oxides

X-ray structural analysis of crystalline alkoxides in many cases reveals that along with OR-groups their molecules also contain oxo-ligands. The following possible reactions leading to formation of oxoalkoxides have been discussed: hydrolysis, pyrolysis (frequently uncontrollable), ether elimination, oxidation of OR-groups (which exist in solutions of alkali, alkaline-earth and rare earth elements), or alkoxides of the lower oxidation states (which are formed by reduction of M(OR) _n on cathode during electrolysis or by hydrogen in statu nascendi). Oligomeric oxoalkoxides differ from the polymeric alkoxides M(OR) _n in considerably higher solubility and reactivity. The most important role of oxoalkoxides in the processes of formation of oxides has been demonstrated using as an example preparation of BaTiO₃ from alkoxides.     

波长色散X射线荧光光谱法测定钴精矿中钴、铜和锰含量

采用高纯氧化物经四硼酸锂和偏硼酸锂熔融制备人工标准样品,以氧化镱为内标,制作校准曲线,建立了波长色散型X射线荧光光谱法测定钴精矿中钴、铜、锰元素的分析方法。重点研究了混合熔剂、试样稀释比、氧化剂和内标选择、方法检出限、方法准确度和精密度等,结果表明,各元素校准曲线线性范围宽,相关系数均大于0.999, 钴、铜、锰元素检出限分别达到0.002%、0.001%和0.001%,测试准确度和精密度可靠,方法满足行业检测需求。