Synthesis, structure and properties of new chain cuprates, Na3Cu2O4 and Na8Cu5O10

Na₃Cu₂O₄ and Na₈Cu₅O₁₀ were prepared via the azide/nitrate route from stoichiometric mixtures of the precursors CuO, NaN₃ and NaNO₃. Single crystals have been grown by subsequent annealing of the as prepared powders at 500 °C for 2000 h in silver crucibles, which were sealed in glass ampoules under dried Ar. According to the X-ray analysis of the crystal structures (Na₃Cu₂O₄: P2₁/n, Z=4, a=5.7046(2), b=11.0591(4), c=8.0261(3) Å, β=108.389(1)°, 2516 independent reflections, R₁(all)=0.0813, wR₂ (all)=0.1223; Na₈Cu₅O₁₀: Cm, Z=2, a=8.228(1), b=13.929(2), , β=111.718(2)°, 2949 independent reflections, R₁(all)=0.0349, wR₂ (all)=0.0850), the main feature of both crystal structures are CuO₂ chains built up from planar, edge-sharing CuO₄ squares. From the analysis of the Cu-O bond lengths, the valence states of either +2 or +3 can be unambiguously assigned to each copper atom. In Na₃Cu₂O₄ these ions alternate in the chains, in Na₈Cu₅O₁₀ the periodically repeated part consists of five atoms according to Cu^II-Cu^II-Cu^III-Cu^II-Cu^III. The magnetic susceptibilities show the dominance of antiferromagnetic interactions. At high temperatures the compounds exhibit Curie-Weiss behaviour (Na₃Cu₂O₄: , , Na₈Cu₅O₁₀: , , magnetic moments per divalent copper ion). Antiferromagmetic ordering is observed to occur in these compounds below 13 K (Na₃Cu₂O₄) and 24 K (Na₈Cu₅O₁₀).     

Leaching of the Anthraquinone Dye Solvent Blue 59 Incorporated into Organically Modified Silica Xerogels

The effects of preparation method and precursor composition on the leaching behavior of the anthraquinone dye Solvent Blue 59 incorporated into silica based xerogels have been studied. Xerogels were prepared under acidic conditions from mixtures of 20 mol% of organically modified silicon alkoxides, R–Si(OR)3, in Si(OR)4 (R = methyl or ethyl, R = methyl, vinyl, phenyl). The dye was added at the beginning of the sol-gel reaction. The reaction was carried out by either hydrolysis under acidic conditions or acidolysis by formic acid. The dye incorporated was leached with refluxing ethanol using a Soxhlet extraction procedure to simulate the long-term stability of the samples prepared. With increasing size of organic substituent (methyl < vinyl < phenyl), the amount of dye leached decreases. Results from nitrogen adsorption experiments show that all samples characterized have about the same average pore diameter, but they differ in total pore volume and BET surface area. With increasing size of the organic residue, the pore volume decreases by an order of magnitude. Therefore, it is concluded that the microstructure of the xerogels prepared determines the retention behavior of dyes incorporated during the sol-gel reaction.     

Ni助剂FeMnK/SiO2费托合成催化剂的结构性质及还原碳化行为研究

研究了Ni助剂对共沉淀型FeMnK/SiO2催化剂的结构性质和还原炭化行为的影响。结果表明，添加少量Ni助剂提高了催化剂的比表面积，降低了平均孔径，促进了催化剂中铁氧化物的分散。在H2-TPR中，Ni助剂降低了催化剂的还原温度；在CO-TPR中，Ni助剂使催化剂的还原和炭化峰前移，提高了氧的移除速率，增加了碳的引入量；在合成气等温还原中，Ni助剂提高了催化剂的活化速率，在相同的还原时间内可获得更高的F-T合成反应活性。     

PYRIDINATION OF POLY（VINYL CHLORIDE） via A HOMOLYTIC PATHWAY

PVC was subjected to a chemical modification aiming at replacing the chlorine atoms by pyridine groups via a homolytic route. Pyridine groups were peculiarly affixed to the PVC matrix via a carbon-carbon bond rather than a carbon-nitrogen one. PVC was first iodinated using the Conant-Finkelstein reaction, followed by the application of the homolytic conditions of Minisci to generate pyridinated PVC with a varying degree of substitution. The extent of substitution was not high; the reaction on 30% iodinated PVC afforded a degree of modification no greater than 3%.     

制备参数影响ZrO2气凝胶结构特性的机理

探讨了胶凝顺序、老化介质和氨水溶度影响样品结构的内在机理，结果表明，ＺｒＯ２样品形貌的不同是由于或胶凝顺序不同而引起的水解和缩聚的进程不同，或老化介质不同而引起的老化机理不同所致。氨水浓度的影响一方面与粒子活动体积有关，一方面与氨水中的水抑制缩聚有关。且经过老化后使其影响更加明显。     

新型锂离子电池CaSnO3负极材料的湿化学制备与电化学性能

采用湿化学方法合成了具有钙钛矿结构的CaSnO₃，将其作为锂离子电池的负极活性物质，研究了其电化学性能。结果表明，湿化学方法制备的锡酸钙，粒度分布集中、平均粒径在500 nm左右，在0～1.0 V之间以0.1 C倍率充放电时，其可逆容量达到469 mAh·g^-1，而且循环性能良好。经80次循环后的容量衰减率只有0.57%。从首次放电容量和可逆容量来看，锡酸钙的储锂机制与锡基氧化物材料相似，即:首先是结构的还原并形成金属锡；然后金属锡与锂发生可逆的合金化与去合金化过程。锡酸钙的可逆容量、循环性能都比文献报道的块状锡氧化物或者是无定型锡基复合氧化物好，这说明钙钛矿结构和钙离子的存在可能对改善锡基负极材料的性能是有益的。     

Solvothermal Route to Prepare the Metastable Phase 3c-Fe7S8 with Hexagonal Platelet Morphology

The metastable phase 3c-Fe7S8 with the hexagonal platelct morphology has been prepared by using solvothermal route.The product was characterized by mcans of X-ray powder diffraction(XRD) and transmission electron microscopy (TEM) and X-ray photoelectron speetra (XPS).The experiment results show that the as-prepared Fe7S8 is a metastable phase with the hexagonal platelet morphology.     

新型锂离子电池CaSnO_3负极材料的湿化学制备与电化学性能

采用湿化学方法合成了具有钙钛矿结构的CaSnO3,将其作为锂离子电池的负极活性物质,研究了其电化学性能。结果表明,湿化学方法制备的锡酸钙,粒度分布集中、平均粒径在500nm左右,在0￣1.0V之间以0.1C倍率充放电时,其可逆容量达到469mAh·g-1,而且循环性能良好。经80次循环后的容量衰减率只有0.57%。从首次放电容量和可逆容量来看,锡酸钙的储锂机制与锡基氧化物材料相似,即:首先是结构的还原并形成金属锡;然后金属锡与锂发生可逆的合金化与去合金化过程。锡酸钙的可逆容量、循环性能都比文献报道的块状锡氧化物或者是无定型锡基复合氧化物好,这说明钙钛矿结构和钙离子的存在可能对改善锡基负极材料的性能是有益的。     

关于旅游路线规划问题的建模与研究

近年来,随着我国国民经济的快速发展和人们生活水平的提升,自驾游在全国旅游业中的比重逐渐增大.以旅游爱好者常住地——西安市为例,采用分步优化、聚类分析、蚁群优化算法、0-1规划、层次分析等数学方法,使得游览全国201个5A级景点的时间最短、费用最低、旅游体验度最优.     

最小Hamilton回路是最优旅行商路线的条件

本文给出并证明了一个非完全图 G的最小 Hamilton回路必为最优旅行商路线的条件是除了应满足广义三角不等式外 ,还必须满足正则收缩性