YBaCo4O7及YBaCo4O8.5中六角超结构的电子衍射分析

制备了氧化学剂量样品.YBaCo4O7,通过电子衍射谱分析确定为六角结构,晶格常数a=0.629(5)nm,c=1.023(5)nm;制备的氧非化学剂量样品YBaCo4O8.5中,过量的氧是以超结构的方式存在.通过电子衍射方法确定了其中一种六角超结构相,其晶格参数as=bs=1.090(4)am,cs=1.002(6)...     

正极材料Li[Ni_(1/3)Li_(1/9)Mn_(5/9)]O_2的结构和充放电过程研究

应用X射线衍射,选区电子衍射和同步X射线衍射等方法,对锂离子电池正极材料Li[Ni1/3Li1/9Mn5/9]O2的结构和充放电行为进行了研究.结果表明Li[Ni1/3Li1/9Mn5/9]O2可标定为单相α-NaFeO2,并具有3ahex.×3ahex.×3chex.超结构特征.电池充电时,伴随锂离子的脱出,相邻氧原子层间的静电斥力逐渐增大,当电压为3.8V时应力达到最大.接近4.6V时,晶胞常数c急剧下降,绝大多数Li 从材料的锂层拔出,Ni2 发生氧化.4.6～4.8V之间c增大,a变化很小,说明过渡金属层中的Li 拔出,而过渡金属离子的氧化状态未改变.     

Supramolecular template-directed synthesis of perfect phenelenediimino-bridged ladderlike polyphenylsiloxanes

A template synthesis of the soluble, high molecular weight (Mw), and perfect p-phenylenediimino (p-PDA)-bridged ladderlike polyphenylsiloxane (PLPS) is reported. First, N,N'-bis(phenyldichlorosilyl)-p-PDA monomers were self-assembled into a perfect ladder superstructure (LS) by concerted interaction of aromatic pi-pi stacking and hydrogen bonding. Then the LS underwent a novel stoichiometric hydrolysis/dehydrochlorination-condensation reaction instead of the usual hydrolysis/dehydration-condensation reaction, leading to the PLPS. The perfect ladder structures of both the PLPS and, in particular, the unstable supramolecular LS were confirmed as follows. 1) There are two Bragg peaks in solid and/or solution X-ray diffraction (XRD) spectra representing the ladder width (w) and ladder thickness (t); these peaks were consistent with those calculated by molecular simulation. 2) Both the PLPS and LS have extremely sharp absorption peaks with small half-peak widths (Delta(1/2) < 0.3 ppm) in 29Si NMR spectra, suggesting the presence of the perfect ladder structure for PLPS and LS. 3) Moreover, no noticeable absorption peaks for the Si-OH and NH2 groups were observed in FT-IR and 29Si NMR spectra, indicating that the Si-N bond of the [triple bond]Si-NH-C6H4-NH-Si[triple bond] ladder rung of PLPS and LS is not cleaved. 4) Both PLPS and LS show similar emission peaks (in fluorescence spectroscopy) attributed to the excimer formed by face-to face pi-pi stacking of phenyl groups along the ladder chain rather than a branched direction. 5) Differential scanning calorimetry (DSC) measurements indicate a high glass temperature (Tg = 176.4 degrees C) for PLPS. As circumstantial evidence, this result further indicates very high stiffness of PLPSs ladder backbone as compared with flexible single-chain polyphenylmethylsiloxane with a low Tg = -69.4 degrees C.     

LADDER SUPERSTRUCTURE-DIRECTED SYNTHESIS OF A WELL-DEFINED m-PHENELENEDIIMINO-BRIDGED LADDER POLYMETHYLSILOXANE

A well-defined m-phenylenediimino-bridged ladder polymethylsiloxane(LP) was first synthesized through a welldefined ladder superstructure(LS) acting as synthetic template,which was self-assembled by concerted interaction of hydrogen bonding and aromaticπ-πstacking of the monomer(M),N,N'-bis(phenyldichlorosilyl)-m-phenylenediamine.Some key characterization data of LP and,in particular,the extremely vulnerable LS with very unstable Si-Cl and Si-N groups were given.The molecular weights(M_n) of LS and LP ar...     

Σ-Definability in Hereditarily Finite Superstructures and Pairs of Models

We consider the problem of being -definable for an uncountable model of a c-simple theory in hereditarily finite superstructures over models of another c-simple theory. A necessary condition is specified in terms of decidable models and the concept of relative indiscernibility introduced in the paper. A criterion is stated for the uncountable model of a c-simple theory to be -definable in superstructures over dense linear orders, and over infinite models of the empty signature. We prove the existence of a c-simple theory (of an infinite signature) every uncountable model of which is not -definable in superstructures over dense linear orders. Also, a criterion is given for a pair of models to be recursively saturated.     

超结构换热器网络综合优化的遗传/模拟退火算法-Ⅱ.遗传/模拟退火算法及应用

本文提出了用于换热器网络综合的改进的遗传/模拟退火算法.最优综合的模型基于本文第一部分所提出的通用解方法.所采用的遗传算法结合了模拟退火算法和爬山优化算法,同时引进精英策略和结构变异策略以增强算法的搜索能力.采用本文提出的算法对文献提出的算例进行了计算并得到了更好的结果.     

Structure and Specific Heat of Disordered and Ordered Titanium Monoxide TiOy

The structure of disordered and ordered titanium monoxide containing structural vacancies in both sublattices was studied by Xray diffraction. The symmetry of the monoclinic Ti₅O₅ superstructure (space group C2/m) was analyzed. The type and channel of the TiO_y–Ti₅O₅ disorder–order transition was determined. The distribution functions of Ti and O atoms in the metal and nonmetal sublattices of titanium monoxide were calculated. The specific heats of TiO_y titanium monoxides (0.8< y< 1.27) were measured by differential scanning calorimetry for the disordered and ordered states in the range from 340 to 600 K. The dependences of the specific heat, enthalpy, and entropy on the composition and structure of TiO_y were found for the first time. A notable effect of the structural state on the specific heat was detected. In the indicated temperature range, the C _p (T) dependence is adequately described by a function that accounts for the Debye effect and the electronic specific heat.     

Cu_2O@HKUST-1前驱物法合成CuO中空管状超级结构及其CO催化氧化性能

以Cu_2O@HKUST-1(HKUST-1=Cu_3(BTC)2,BTC~(3-)=均苯三甲酸离子)线状核@壳结构为前驱体,通过在碱性条件下原位水解HKUST-1壳、氧化刻蚀Cu_2O核的方法得到了一种新型的、由相互交错的CuO纳米片构筑的、中空管状的超级结构,并研究了其对CO氧化的催化活性。结果表明,这种中空的CuO管状超级结构具有较大的比表面积(56.3 m~2/g)和可观的催化活性,催化剂对CO的完全转化温度为200℃,190℃时转化效率为17.3 mmolCO/(gCuO·h)。     

Crystal Structure of Pseudorhombohedral InFe1−xTixO3+x/2 (x=2/3)

The structure of pseudorhombohedral-type InFe_1−xTi_xO_3−x/2 (x=2/3) was refined by Rietveld profile fitting. The crystal is a commensurate member of a series in a solution range on InFeO₃-In₂Ti₂O₇ including incommensurate structures. The structure with the unit cell of a=5.9188(1), b=10.1112(2), and c=6.3896(1) Å, β=108.018(2)°, and a space group P2₁/a is the alternate stacking of an edge-shared InO₆ octahedral layer and an Fe/Ti-O plane along c^*. Metal sites on the Fe/Ti-O plane are surrounded by four oxygen atoms on the Fe/Ti-O plane and two axial ones. Electric conductivities of the order 10⁻⁴ S/cm were observed for the samples at 1000 K, while the oxide ion transport number is almost zero as no electromotive force was detected by an oxygen concentration cell.     

桩-土-上部结构相互作用体系的非线性地震反应分析

本文采用双线性等向硬化模型考虑结构的非线性,并用Drucker-Prager理想弹塑性模型模拟土的非线性,同时在桩-土接触面上设置接触单元模拟桩-土间的非线性,建立了一个桩-土-上部结构相互作用体系的有限元分析模型,对不同的建筑场地条件下桩-土-上部结构相互作用体系的地震响应进行了探讨,分析了结构的内力以及变形分布情况,得到了一些有应用价值的结论．