D_yFe_(10)Si_2N_x化合物的结构与磁性

利用中子粉末衍射技术确定了77 K温度下化合物中Si原子占位和原子磁矩,研究了DyFe10Si2化合物低温下的结构与磁性．结果表明,在77 K化合物的易磁化方向与ab平面之间有较小的夹角．采用全势能线性缀加平面波((L)APW)+局域轨道(10)方法计算了DyFe10Si2及其氮化物的磁性和间隙原子效应,分析了化合物中间隙N原子在Si原子不同占位时的作用．结果表明,N原子的杂化作用能提高化合物的饱和磁矩(不显著),使其居里温度有显著的提高(15％-20％)．

·Cl引发3种环状含有NH结构有机化合物的大气转化机制及动力学

氯自由基(·Cl)的高氧化性及其内陆来源的新发现使得·Cl在评估有机污染物的大气归趋方面起着比以往更为重要的作用。含有NH x(x=1,2)结构的有机化合物不仅是大气中一类潜在的有机污染物,也是大气中致癌性亚硝胺的前驱体-N中心自由基的重要来源。前人研究发现,·Cl与含有NH x(x=1,2)结构的有机化合物具有独特的相互作用且其反应具有结构依赖性。目前,大多数研究只关注链状含有NH x(x=1,2)结构有机化合物的反应,而对于环状含有NH结构有机化合物的反应研究却很少。本研究使用量子化学和动力学模拟相结合的方法研究·Cl引发3种环状含有NH结构有机化合物(吗啉(MOR)、哌啶(PIP)和吡咯烷(PYR))的大气转化机制及动力学。结果发现,·Cl夺取3种环状含有NH结构有机化合物中N-H的H原子形成N中心自由基是最可行的反应路径。在298 K和1 atm下,计算的反应速率常数分别为5.×10^-10(MOR)、5.1×10^-10(PIP)和4.9×10^-10(PYR)cm 3·molecule^1·s^-1,且具有正的温度依附性。结合可获得的·OH引发反应的反应速率常数,评估·Cl对MOR和PIP转化的贡献分别为·OH的2.6%~26%和6.9%~69%。上述研究结果为将来建立·Cl引发含有NH x(x=1,2)结构有机化合物反应的结构-活性关系、全面评估含有NH x(x=1,2)结构有机化合物的大气归趋和环境风险提供数据支持。

Extraction and Crystal Structure of Karounidiol

The title compound of karounidiol (C30H48O2), a main active triterpene component of snakegourd seed, was isolated from unsaponifiable matter of the seed oil of Trichosanthes kirilowii Maxim., and characterized by X-ray diffraction analysis. It crystallizes in orthorhombic system, space group P212121 with C30H48O2CH3OHH2O (C31H54O4), a = 7.515(1), b = 14.407(1), c = 27.799(2) , V = 3009.8(5) 3, Z = 4, Dx = 1.087 g/cm3, Mr = 490.77, F(000) = 1088 and = 0.086 mm-1. The final R = 0.0840 and wR = 0.2289 for 2752 observed reflections (|F|2 ≥ 2|F|2). The molecular crystal structure of karounidiol shows relative stereochemistry of (3,13,14, 20)-3,29-dihydroxy-13-methyl-26-norolean-7,9(11)-diene. The molecule is composed of five six- membered rings with ring junctures of A/B trans, C/D trans and D/E cis.

Preparation of Bi_2WO_6 Photocatalyst and Its Application in the Photocatalytic Oxidative Desulfurization

A type of visible light photocatalyst Bi2WO6 was prepared from Bi(NO3)3.5H2O and Na2WO4.2H2O by means of hydrothermal method and was characterized by UV-vis diffuse reflectance spectrometry and XRD.Oxidative desulfurization via photocatalysis was investigated using thiophene dissolved in octane as the model compound,with hydrogen peroxide used as the oxidant.The effects of hydrogen peroxide mass fraction,irradiation time,dosage of photocatalyst Bi2WO6 on the desulfurization efficiency were also investigated.Under suitable conditions,the desulfurization rate of model compound reached over 70%.

Synthesis and Crystal Structure of Methyl(7,7-Dimethyl-2-amino-4-(4-chlorophenyl)-5-oxo-5,6,7,8-tetrahydro-4H-benzo-[b]-pyran-3-yl)Carboxylate

The title compound methyl (7,7-dimemyl-2-amino-4-(4-chlorophenyl)-5-oxo-5,6,7,8-tetrahydro-4H-benzo-[b]-pyran-3-yl) carboxylate (C19H20ClNO4, Mr = 361.81) was synthesized and crystallized. The crystal belongs to triclinic, space group P 1 with a = 8.519(2), b = 10.346(2), c = 11.481(3) A, α = 108.16(1), β = 107.78(2), γ= 91.83(2)°, Z = 2, V = 906.5(3) A3, Dc = 1.326 g/cm3, μ(MoKα) = 0.234 mm-1, F(000) = 380, R = 0.0467 and wR = 0.1270 for 3142 observed reflections (I > 2σ(I)). X-ray analysis reveals that the C(7), C(8), C(9), O(1), C(10) and C(11) atoms form a six-membered ring which adopts a boat conformation. In the ring, the distances of C(8)-C(9) and C(10)-C(11) are 1.332(3) and 1.357(3) A, respectively, which indicates that they are C=C double bonds. Another six-membered ring (C(8)-C(9)-C(15)-C(14)-C(13)-C(12)) adopts the half-chair confonnation. In addition, there are intermolecular hydrogen bonds in the crystal structure.

Reduction of Panzhihua titanium-bearing oxidized pellets by CO-N_2-H_2 gas

The effect of H_2 gas content on the reduction of Panzhihua titanomagnetite concentrate pellets by carbon monoxide was investigated by isothermal reduction experiment using CO-N_2-H_2 gas mixtures in a vertical electric resistance furnace.The morphology and phase transformation of reduced samples obtained were detected by scanning electron microscopy,energy disperse spectroscopy analysis and X-ray diffractometry respectively.The results show that increasing H_2 content will enhance the initial stage of reduction rate apparently.There are two reasons responsible for this effect,one is that H_2 accelerates the chemical reaction,and the other is that the addition of H_2 gas can improve the porosity of pellet intensively.It is noteworthy that this effect is more obvious when the reduction temperature reaches 1473 K with sticking phenomenon happening.There are no crystalline phases which can be found such as ulvospinle,ilmenite,ferrous-pseudobrookite and any titanium oxide except titanomagnetite(TTM).The reduction progress is suggested as follows:1) Fe_2O_3→Fe_3O_4→FeO→Fe;2) Fe_2TiO_5→Fe_2TiO_4+Fe_3O_4→TTM.Element Al migrates and gets enriched in high titanium content iron ores,and eventually Al to Ti molar ratio is 1:3.Al is likely to dissolve in titanium iron oxides to form a kind of composite iron compound,which results in the restrain of reduction.

Support effect of zinc tin oxide on gold catalyst for CO oxidation reaction

Nanostructured gold catalyst supported on metal oxide is highly active for the CO oxidation reac‐tion. In this work, a new type of oxide support, zinc tin oxide, has been used to deposit 0.7 wt%Au via a deposition‐precipitation method. The textural properties of Zn2SnO4 support have been tuned by varying the molar ratio between base （N2H4＆#183;H2O） and metal ion （Zn2＋） to be 4/1, 8/1 and 16/1. The catalytic tests for CO oxidation reaction revealed that the reactivity on Au‐Zn2SnO4 with N2H4＆#183;H2O/Zn2＋ = 8/1 was the highest, while the reactivity on Au‐Zn2SnO4 with N2H4＆#183;H2O/Zn2＋ =16/1 was almost identical to that of the pure support. Both fresh and used catalysts have been characterized by multiple techniques including nitrogen adsorption‐desorption, X‐ray diffraction, transmission electron microscopy, high‐angle annular dark‐field scanning transmission electron microscopy, X‐ray photoelectron spectroscopy, X‐ray adsorption fine structure, and tempera‐ture‐programmed reduction by hydrogen. These demonstrated that the textural properties, espe‐cially pore volume and pore size distribution, of Zn2SnO4 play crucial roles in the averaged size of gold nanoparticles, and thus determine the catalytic activity of Au‐Zn2SnO4 for CO oxidation.

[(n-C_4H_9)_3SnO_2C(CH_2)_2CO_2Sn(C_4H_9-n)_3]: A Novel Three-dimensional Framework Structure of Organotin Complex

The bis(tributyltin) ester of succinic acid was synthesized by the reaction of disodium salt of succinic acid with tributyltin chloride in a molar ratio of 1:2. The crystal structure was determined by X-ray single-crystal diffraction. It belongs to orthorhombic with space group Pccn, a = 20.949(3), b = 17.470(3), c = 20.345(3) Angstrom, V = 7446(2) Angstrom(3), Z = 8, D-c = 1.242 g/cm(3), mu = 1.365 mm(-1), F(000) = 2864, R = 0.0544 and wR = 0.1417. The tin atom is of five-coordination in a trigonal bipyramidal structure by bridging two carboxylate groups in different directions and the resulting structure which contains straight twist large ring channels along the axes of a, b and c is a three-dimensional framework polymer containing two different tin atoms.

Study on Deactivation by Sulfur and Regeneration of Pd/C Catalyst in Hydrogenation of N-（3-nitro-4-methoxyphenyl） Acetamide

Deactivation of Pd/C catalyst often occurs in liquid hydrogenation using industrial materials. For in-stance, the Pd/C catalyst is deactivated severely in the hydrogenation of N-(3-nitro-4-methoxyphenyl) acetamide. In this study, the chemisorption of sulfur on the surface of deactivated Pd/C was detected by energy dispersive spec-trometer and X-ray photoelectron spectroscopy. Sulfur compounds poison the Pd/C catalyst and increase the forma-tion of azo deposit, reducing the activity of catalyst. We report a mild method to regenerate the Pd/C catalyst: wash the deposit by N,N-dimethylformamide and oxidize the chemisorbed sulfur by hot air. The regenerated Pd/C cata-lyst can be reused at least ten runs with stable activity.

LiXAlF_6:xCe^(3+)(X=Ca,Sr,Ba)的发光研究

光激励发光材料一直是人们竞争研究的对象。为在较短的时间内在发光中心存储更多的电子,要寻找一种荧光材料作为光激励发光材料的增感材料,使光激励发光材料敏化,从而提高光激励发光强度,这是提高激发光源利用率的最佳途径。通过对用紫外光源作激发源的光激励发光材料发光机理的研究,确定在紫外波段靠近短波方向的光可能使这种光激励发光材料敏化。Ce3+在氟化物体系中的发射通常位于紫外波段,对Ce3+掺杂浓度为x的LiXAlF6:xCe3+(X=Ca,Sr,Ba,x=0.002￣0.012mol)一系列荧光材料作了研究,研究其发光是否在紫外波段,哪种基质更适合需要。采用高温固相法制备,研究该3种化合物的发射光谱及发射光谱随Ce3+掺杂浓度的变化。结果找到了最有可能作为用紫外光源作激发源的光激励发光材料的最佳Ce3+掺杂浓度的基质LiBaAlF6:xCe3+(x=0.010mol)。

Bi2Te3-xSex(X≤3)同晶化合物电子结构的第一性原理研究

本文采用基于密度泛函理论的第一性原理全势能线性缀加平面波方法(FLAPW),分析了Bi2Te3-xSex体系中各原子自旋轨道耦合(SOI)的p1/2修正对体系性质的影响,并对Bi2Te3-xSex(x≤3)同晶化合物的电子特性进行系统的理论研究,首次计算出Bi2Se2Te的电子特性.计算结果表明:对于Bi2Te3-xSex体系中的Te原子和Bi原子考虑SOI的p1/2修正,对体系费米能级附近能带结构的计算分析尤为重要,而对于Bi2Se2Te和Bi2Te2Se中的Se原子是否考虑SOI的p1/2修正对费米能级附近的能带结构无显著影响;Bi2Te3-xSex(x≤3)均为间接带隙窄带半导体,体系在费米能级附近Γ点的能带趋势相近,强的杂化压低了价带的最高峰,使得两个边锋提高,在Γ点形成马鞍点;体系费米能级附近的电子态密度主要来源于各原子p态电子贡献;层间原子成键,X(1)—Bi键比X(2)—Bi键(X=Te,Se)的共价键成分较强;随着体系中Se原子摩尔比的增加,晶胞的体积减小,体系的能量增加,Te(1)—Bi键、Se(2)—Bi键、Se(1)—Bi键的共价键成分逐渐增强.

Preparations of Complex Bimetallic Oxides from Bimetallic Assemblies Containing Different Copper（Ⅱ） Precursors and Comparison of Some Related Systems

This is a mini-review-like article including our recent results and methods for （new） metal oxides and （previously reported） composite materials composed of metal complexes and metal oxides for comparison to enhance anisotropic structural changes intentionally. Some complex inorganic oxides are known that they may be promising color materials （absorbing visible light of certain wavelengths region） having potential application for environmentally benign catalysts, for example, photocatalysts. Chiral copper（Ⅱ） complexes having bidentate amine ligands （[CuL2]2＋） can be acted as cationic building blocks of bimetallic metal complexes. We have prepared some chiral bimetallic complexes with various anionic metal complexes such as [PtCl4]2-, [M02O7]2 and Mn12 clusters （typical single-molecule magnets） which characterized by means of solid-state electronic and CD （circular dichroism） spectra, IR （infrared） spectra, synchrotron XRD （X-ray diffraction） and XAS （soft X-ray absorption spectroscopy）. By sintering these precursor chiral bimetallic complexes, we have prepared complex inorganic oxides from them. The IR spectra indicated substituting metal-ligand bonds and losing organic moieties. The XRD pattern indicated complete changes of crystal structures. The XAS revealed replacing coordination atoms as well as oxidation of valences of metal ions. Furthermore, we will also investigate possibility of patterning by homogeneous precipitation method as bimetallic complexes to prepare desirable complex inorganic oxides.

铝铜合金的晶界偏析行为及析出相的理论研究

晶界偏聚行为及析出相形成对铝铜合金的力学性能提升至关重要。为研究铝铜合金中Cu元素与Al基体的相互作用,本文基于密度泛函理论,利用第一性原理方法计算了Al∑5(210)[001]晶界Cu元素的偏析能、电荷密度分布等性质,并结合AFLOW的高通量框架系统研究了不同铝铜二元析出相的晶格常数、形成能和弹性常数等信息。晶界模拟结果表明,由于尺寸效应和成键性质的变化,Cu原子在晶界上形成能更低,更易于偏聚到晶界GB2位置,偏聚能为-0.42 eV。高通量计算结果验证了在不同Cu浓度下,铝铜二元体系中会产生大量形成能为负的亚稳相,以及4种稳定的基态结构AlCu_(3),Al_(4)Cu_(9),AlCu和Al_(2)Cu。以上4种化合物的形成能分别为-0.19,-0.21,-0.20,-0.18 eV/atom,与铝基体相比,其体弹性模量和剪切模量分别提高约20%和90%。

压水堆燃料棒UO_(2)燃料芯块与锆合金包壳化学相互作用层研究

反应堆运行期间,锆合金包壳与燃料接触后不断氧化,与燃料结合形成牢固的化学相互作用层,影响燃料间隙热导、包壳力学性能和燃料包壳机械相互作用。本文以压水堆核电站燃耗45 GWd·t U^(-1)完整燃料棒为研究对象,利用金相显微镜(Metallographic Microscope)、扫描电子显微镜及能谱分析(Scanning Electron Microscopy-Energy Dispersive Spectroscopy,SEM-EDS)和热室内拉曼光谱(Raman Spectroscopy)方法对其化学相互作用层形貌及结构进行分析,国内首次获得堆内辐照后包壳和芯块化学相互作用层相关分析数据。结果表明:运行至45 GWd·t U^(-1)燃耗后,燃料芯块与包壳间隙形成14~19μm的化学相互作用层,不同位置机械接触的时间顺序差异,导致作用层的不连续形成与长大。SEM-EDS结果表明,相互作用层呈“蠕虫”状形貌,且由U、Zr、O三元素构成形成混合相(U,Zr)O_(x)化合物,并且发现化学相互作用层由化学黏附和机械作用共同作用的结果。拉曼光谱显示,化学相互作用层主要由四方相氧化锆(t-ZrO_(2))和单斜相(m-ZrO_(2))相组成。

Synthesis and Crystal Structure of a New Imidazole Coordinated Octamolybdate Compound

The title compound (Himi)4[Mo8O26(imi)2]4H2O (imi = imidazole) 1 was synthe- sized by the reaction of H2MoO4 and imidazole in aqueous solution. Single-crystal X-ray analysis reveals that compound 1 is crystallized in the triclinic system, space group P with a = 10.6219(8), b = 10.7260(8), c = 11.3220(9) , a = 92.842(2), b =117.364(1), g = 101.655(1), C18H36Mo8N12- O30, Mr = 1668.11, V = 1106.8(2) 3, Z = 1, Dc = 2.503 g/cm3, F(000) = 804, m = 2.298 mm-1, the final R = 0.0714 and wR = 0.1651 for 3121 observed reflections with I > 2s(I). The X-ray crystal structure analysis suggests that compound 1 is built up by two imidazole ligands coordinated by the centrosymmetric octamolybdate anions, protonated imidazole cations and crystallization water molecules.

Phase equilibria of Zn-Al-Ti ternary system at 450 and 600℃

The phase relationships in the Zn-Al-Ti system at 450 and 600℃ were experimentally determined using equilibrated alloys method.The specimens were investigated by means of scanning electron microscopy coupled with energy dispersive spectroscopy and X-ray diffractometry.Eleven and eight three-phase regions are confirmed in the 450 and 600℃ isothermal sections,respectively.The Ti2Al5 which only exists at high temperature(990-1199.4℃)in Ti-Al binary system is confirmed in two isothermal sections due to the dissolution of zinc.The T phase is confirmed as a ternary compound rather than an extension phase of TiZn3 at 450℃.The T2 phase is a new ternary phase stable at 450 and 600℃ in Zn-Al-Ti ternary system.

Effects of Thickness on Properties of ZnO Films Grown on Si by MOCVD

High quality ZnO films are successfully grown on Si（100） substrates by metal-organic chemical vapor deposition at 300℃. The effects of the thickness of the ZnO films on crystal structure, surface morphology,and optical properties are investigated using X-ray diffraction, scanning probe microscopy,and photoluminescence spectra, respectively. It is shown that the ZnO films grown on Si substrates have a highly-preferential C-axis orientation,but it is difficult to obtain the better structural and optical properties of the ZnO films with the increasing of thickness. It is maybe due to that the grain size and the growth model are changed in the growth process.

Properties of fluoride film and its effect on electroless nickel deposition on magnesium alloys

The physical characteristics and microstructure of the fluoride film formed during activation were investigated using SEM,XPS and SAM,and its stability in electroless nickel(EN) bath was analyzed.The effects of the fluoride film on EN deposition were studied additionally.The results show that the fluoride film on magnesium alloys is a kind of porous film composed of MgF2 with thickness of 1.6-3.2 μm.The composition of the activation bath and pretreatment of EN processing have influence on the composition of the fluoride film.The fluoride is stable and dissolves little in EN bath;as a result,the fluoride film can protect magnesium substrate from the corrosion of EN bath.The composition of fluoride determines the initial deposition of EN and part of the fluoride film finally exists as inclusion in EN coating.

Electrolyte composition and removal mechanism of Cu electrochemical mechanical polishing

The optimization of electrolytes and the material removal mechanisms for Cu electrochemical mechanical planarization(ECMP)at different pH values including 5-methyl-1H-benzotriazole(TTA),hydroxyethylidenediphosphoric acid(HEDP),and tribasic ammonium citrate(TAC)were investigated by electrochemical techniques,X-ray photoelectron spectrometer(XPS)analysis,nano-scratch tests,AFM measurements,and polishing of Cu-coated blanket wafers.The experimental results show that the planarization efficiency and the surface quality after ECMP obtained in alkali-based solutions are superior to that in acidic-based solutions,especially at pH=8.The optimal electrolyte compositions(mass fraction)are 6% HEDP,0.3% TTA and 3% TAC at pH=8.The main factor affecting the thickness of the oxide layer formed during ECMP process is the applied potential.The soft layer formation is a major mechanism for electrochemical enhanced mechanical abrasion.The surface topography evolution before and after electrochemical polishing(ECP)illustrates the mechanism of mechanical abrasion accelerating electrochemical dissolution,that is,the residual stress caused by the mechanical wear enhances the electrochemical dissolution rate.This understanding is beneficial for optimization of ECMP processes.

Study on Crystallization of Titanium Silicalite Zeolite (Ⅱ)

In order to investigate the rules on formation of zeolite during crystallization of titanium silicalite zeolite (TS-1) the X-ray diffractometry and Foulier transform infra-red spectrometry were applied to track the process of crystallization of titanium silicalite zeolite. The research results revealed that at the initial stage of crystallization the interactions between silica gel and titania gel in the polymer blend could gradually lead to the formation of tiny crystal nuclei with complicated structure that could slowly grow up to form molecular sieves. Quite different from the conventional zeolites that use the acid sites as the catalytically active centers, the oxidative reactivity of the titanium silicalite zeolite was not proportional to its crystallinity and is associated with the oxidative centers of titanium contained in the zeolite.