Trition X-100/C_(10)H_(21)OH/H_2O体系层状液晶中纳米羟基磷灰石粉体的合成

本文以Triton X-100/C10H21OH/H2O体系层状溶致液晶为模板,Ca(NO3)2和(NH4)2HPO4为反应物,在一定的pH条件下,通过三元相图确定了层状液晶单相区域,并合成了羟基磷灰石(HA)纳米颗粒。用傅立叶红外光谱(FTIR),X射线衍射(XRD)和透射电子显微镜(TEM)对产物进行了表征。并考察了不同助表面活性剂浓度和不同表面活性剂浓度对产物的形貌和尺寸的影响。结果表明所制备的HA纳米颗粒平均直径为8~10nm、长度在100nm左右,呈针状。助表面活性剂浓度对HA形貌及尺寸影响不大,但是在一定范围内改变表面活性剂浓度可以起到调控HA纳米颗粒形貌和尺寸的作用。     

Ag/ZnO纳米纤维的制备及光催化性能

采用静电纺丝技术及煅烧法制备了氧化锌纳米纤维, 然后采用水热法将银纳米颗粒负载到了氧化锌纳米纤维表面. 利用X射线衍射(XRD)、 X射线光电子能谱(XPS)、 能量色散X射线光谱(EDX)、 扫描电子显微镜(SEM)及透射电子显微镜(TEM)等技术对合成的Ag/ZnO纳米纤维的结构和组成进行了表征. SEM结果表明, 直径在5~100 nm之间的银纳米颗粒附着在直径在80~330 nm之间的氧化锌纤维表面形成了异质结构. 以常见的有机污染物甲基橙、 亚甲基蓝和罗丹明B等为降解底物, 对Ag/ZnO纳米纤维的光催化性能进行了表征. 结果表明, 负载银纳米颗粒后, 复合催化剂的光催化性能明显提高.     

Ag/ZnO纳米纤维的制备及光催化性能（英文）

采用静电纺丝技术及煅烧法制备了氧化锌纳米纤维,然后采用水热法将银纳米颗粒负载到了氧化锌纳米纤维表面.利用X射线衍射(XRD)、X射线光电子能谱(XPS)、能量色散X射线光谱(EDX)、扫描电子显微镜(SEM)及透射电子显微镜(TEM)等技术对合成的Ag/ZnO纳米纤维的结构和组成进行了表征.SEM结果表明,直径在5~100 nm之间的银纳米颗粒附着在直径在80~330 nm之间的氧化锌纤维表面形成了异质结构.以常见的有机污染物甲基橙、亚甲基蓝和罗丹明B等为降解底物,对Ag/ZnO纳米纤维的光催化性能进行了表征.结果表明,负载银纳米颗粒后,复合催化剂的光催化性能明显提高.     

多次交替浸渍法构筑簇状ZnO的PAN复合纳米纤维膜及其光催化性能

以聚丙烯腈(PAN)与氯化锌(ZnCl2)作为前驱物,采用静电纺丝工艺制备PAN/ZnCl_2复合纳米纤维膜,分别采用多次冷热交替浸渍法和单次冷热静置浸渍法得到簇状PAN/ZnO-1和PAN/ZnO-2复合纳米纤维膜。利用扫描电镜(SEM)、傅里叶红外光谱(FT-IR)、X射线衍射(XRD)、X射线能量色散光谱(XPS)和热重分析仪(TG)对复合纳米纤维膜的表面形貌和微结构进行了表征,并以亚甲基蓝(MB)为污染物模型,评价其光催化降解性能。结果表明:经冷热交替浸渍后,纳米ZnO粒子均匀地附着在PAN纤维表面,尤其在PAN/ZnO-1复合纳米纤维膜表面还出现了花状ZnO粒子;相比单次冷热静置浸渍法处理的PAN/ZnO-2复合纳米纤维膜,经多次冷热交替浸渍的PAN/ZnO-1复合纳米纤维膜循环使用3次后对MB的降解率仍可达到90%以上,具有更好的光催化活性和循环使用性能。同时,MB溶液的初始质量浓度、催化剂用量和染料溶液的pH等因素对样品的的光催化降解率有一定影响。     

SnO2/TiO2复合纳米纤维的制备及光催化性能

采用静电纺丝技术,以聚乙烯吡咯烷酮和钛酸正丁酯为前驱体,制得锐钛矿相TiO2纳米纤维。以TiO2纳米纤维为模板,通过水热合成法,制备了具有异质结构的SnO2/TiO2复合纳米纤维。利用扫描电镜(SEM)、X射线能量色散光谱（EDS）、透射电镜(TEM)和X射线衍射(XRD)等分析测试手段对其形貌和结构进行了表征,结果表明,SnO2纳米粒子均匀地生长在TiO2纳米纤维表面,形成了异质结构的SnO2/TiO2复合纳米纤维材料。通过改变反应物浓度,能有效地实现SnO2/TiO2复合纳米纤维的可控合成。以罗丹明B为模拟污染物,考察了SnO2/TiO2复合纳米纤维的光催化性能,与纯TiO2纳米纤维相比光催化活性明显提高,初步探讨了光催化反应机理。     

纳米纤维增强双层组织引导膜的力学性能及细胞响应

通过热致相分离结合静电纺丝技术,在纳米羟基磷灰石/聚酰胺(n HA/PA)多孔膜基底表面形成不同取向的PA纳米纤维,制备了纤维增强双层组织引导膜.研究了不同转速(0,500,1500 r/min)下,n HA/PA多孔膜表面形成的PA纳米纤维的微观结构及取向情况对力学性能的影响.将双层组织引导膜与MG63细胞共培养,研究细胞在双层组织引导膜周围的生长情况,并通过四甲基偶氮唑盐比色法(MTT)定量研究了细胞的增殖情况.结果表明,热致相分离法制备的n HA/PA多孔膜表面及内部富含多孔结构,n HA晶粒在PA基质中均匀分布.采用静电纺丝法在n HA/PA多孔膜表面构建纳米纤维,随着转速增大,n HA/PA多孔膜表面的PA纳米纤维取向性逐渐增加.引入PA纳米纤维后,双层组织引导膜的力学性能均有增强,在500 r/min转速下,双层组织引导膜中,纳米纤维层与n HA/PA基底应变同时达到最大,拉伸强度达到(39.86±4.73)MPa.细胞实验结果显示,双层组织引导膜周围的细胞生长良好,增殖明显,具有良好的细胞相容性,在牙周组织缺损再生领域有潜在应用前景.     

p-CuO/n-In_2O_3异质结纳米纤维的制备及气敏特性

以电纺In_2O_3纳米纤维为模版,通过溶剂热法构建了p-CuO/n-In_2O_3异质结纳米纤维.采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)和X射线光电子能谱(XPS)等方法对所得材料的形貌和结构进行表征.结果表明,CuO纳米颗粒可以均匀地负载在超细In_2O_3纳米纤维表面;随着反应液中乙酸铜浓度的增加,负载的CuO纳米颗粒密度也逐渐增加.通过制备旁热式气敏器件对复合纳米纤维材料的气敏特性进行了研究.结果表明,与纯In_2O_3纳米纤维相比,p-CuO/n-In_2O_3异质结纳米纤维对H_2S气体具有较高的灵敏度和较低的工作温度.     

Pt/TiO2纳米纤维的制备及其对甲醇的电催化氧化活性

采用静电纺丝技术结合还原浸渍法制备了Pt/TiO₂纳米纤维电催化剂, 通过X射线衍射(XRD)分析、扫描电镜(SEM)、透射电镜(TEM)和X射线能谱(EDS)等测试手段对样品的晶相、形貌、微结构和化学组成进行了表征. 测试结果表明, TiO₂纳米纤维为锐钛矿和金红石组成的混晶, Pt 纳米颗粒均匀地分布于TiO₂纳米纤维的表面, 且Pt 颗粒大小较均一, 平均粒径为4.0 nm, Pt/TiO₂纳米纤维中Pt 的质量分数约为20%. 采用三电极体系的循环伏安和计时电流电化学分析方法研究了样品在酸性溶液中对甲醇的电催化氧化活性, 结果表明, 与负载相同质量分数Pt 的Pt/P25 和商业Pt/C 催化剂相比较, Pt/TiO₂纳米纤维催化剂对甲醇呈现出较高的电催化氧化活性和更好的稳定性.     

憎水性金纳米粒子的制备、表征与形貌控制

在十六烷基三甲基溴化铵(CTAB)或十八胺(C18NH2)/正庚烷/乙醇/HAuCl4.4H2O W/O型微乳液体系中,利用简单的加热手段通过乙醇还原法制备了具有不同形貌和尺寸的憎水性金纳米材料。由CTAB或C18NH2稳定的金纳米颗粒运用紫外可见光谱(UV-vis)、透射电镜(TEM)和X射线衍射(XRD)等分别进行了表征和分析。用混合表面活性剂(CTAB/C18NH2)替代单一表面活性剂(CTAB)可以削弱CTAB对金纳米晶体生长的导向作用并提高粒子的单分散性。     

离子液体中纤维素/纳米层状ZnO复合抗菌纤维的制备及性能

以表面活性剂十二烷基磺酸钠(SDS)为模板,Zn(NO_3)_2·6H_2O和NaOH为锌源和沉淀剂,通过改进的模板法在温和条件下制得纳米层状ZnO.以离子液体1-烯丙基-3-甲基咪唑氯盐([Amim]Cl)为溶剂,木浆纤维素和纳米层状ZnO为原料,采用溶液共混方法,通过干湿法纺丝制备了ZnO质量分数分别为3%,5%,7%及9%的纤维素/ZnO纳米复合纤维.采用X射线衍射(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)、场发射扫描电子显微镜(SEM)及热重分析(TG)等方法对纳米层状ZnO及纤维素/ZnO复合纤维进行了表征,并探讨了ZnO的加入对复合体系流变性的影响,同时对复合纤维进行了力学和抗菌性能测试.研究结果表明,所制备氧化锌纯度高,且呈现出重复周期为3.58 nm的层状结构,抗菌性能优异.纳米层状ZnO的加入提高了纤维素纤维的热稳定性和机械强度,同时赋予纤维对金黄色葡萄球菌和大肠杆菌的抑菌性.ZnO片层被纤维素链剥离,并均匀分散于纤维素/ZnO复合物中.ZnO的加入增大了纤维素溶液的黏度,当ZnO含量达到5%以上时,在整个频率范围内,弹性模量大于损耗模量,纳米粒子可稳定悬浮.     

Syntheses and crystal structures of two new coordination polymers of Cd(II) using organic spacer and inorganic-bridging ligands

Two new cadmium (II) complexes [Cd(hmt)(dca)₂] _n (1) and [Cd₃(hmt)₂(SeCN)₆(H₂O)₂] _n (2) (hmt=hexamethylenetetramine, dca=dicyanamide) have been synthesized and characterized by X-ray single-crystal analysis. The complex 1 is a 2D rectangular grid of octahedral cadmium (II) with CdN₆ chromophore where cadmium centers are doubly bridged by dicyanamide and hmt along a-axis, which are interlinked by dicyanamide running along c-axis. Whereas, complex 2 is a 1D chain of octahedral cadmium (II) with a three-leg ladder topology running along a-axis. The Cd(II) centers are doubly bridged through SeCN (infinite rail) along a-axis and singly bridged by hmt (two-step rung) along c-axis, having cadmium centers with CdSe₂N₃O and CdSe₂N₄ chromophores. The adjacent chains through H-bonding between coordinated water and hmt, and SeSe interaction are extended to 2D supramolecular architecture.     

Study of structure and polymerization of epitaxially grown SiPc(OH)2 thin films by high-resolution electron microscopy

Thin films of SiPc(OH)₂ (Pc = phthalocyanine) were formed epitaxially on the (001) surface of mica by vacuum deposition and were then polymerized by heat treatment. The molecular packing of the SiPc(OH)₂ was determined by electron diffraction and high-resolution electron microscopy as triclinic${\rm P\bar 1} $ having dimensions a = 0.727, b = 1.307, c = 0.688 nm, α = 102.5, β = 104.2, and γ = 97.4°. This monomer crystal grows with its c-axis parallel to the a-axis of the substrate mica and its bc-plane parallel to the (001) surface of mica. By heat treatment at 320°C, the SiPc(OH)₂ polymerized with the c-axis of the polymer parallel to the c-axis of the monomer. At 420°C, the c-axis of the polymer became parallel to the a*-axis of the monomer (i.e., perpendicular to the film surface). From high-resolution electron microscopy of partially polymerized specimens, the polymerization was shown to start at the edges of small monomer crystals. This may be considered to be due to the volume expansion during the polymerization. © 1993 John Wiley & Sons, Inc.     

Preparation of mordenite composite membranes with seeding

Mordenite composite membranes were prepared by means of coating a porous α-alumina support with nanosized mordenite seeds followed by hydrothermal crystallization. A systematic investigation was performed on the influence of several factors such as ageing of the reaction mixture, alkalinity, salt addition and temperature on the formation of a mordenite membrane on the seeded support. The ageing of the reaction mixture reduces the growth rate of mordenite crystal along a-axis and b-axis but hardly influences the growth rate along c-axis. As a result, the boundaries between the surface crystals become a little larger with prolonging the period of ageing time. The growth rate of the mordenite crystal along individual axes increases first and then decreases with increasing concentration of sodium hydroxide. A higher alkalinity is unfavorable for the formation of a continuous mordenite membrane. The addition of salt in the reaction mixture has different effect on the growth rate of the mordenite crystal along each axis. With increasing the amount of salt, there was hardly influence on the growth rate along c-axis, whereas an obvious decline was observed in the growth rate along either a-axis or b-axis, which enlarges the boundaries between the surface crystals. The growth rate of the mordenite crystal increases more along c-axis than that along a-axis or b-axis with increasing temperature for hydrothermal crystallization. The use of a temperature as high as 473 K produces a membrane composed of bar-like crystals with larger boundaries. __________ Translated from Journal of Zhejiang University (Science Edition), 2005, 32(4) (in Chinese)     

Modulated Structure of the Composite Crystal Ca0.83CuO2

We have determined the crystal structure of the quasi one-dimensional cuprate Ca_0.83CuO₂, known as Ca₄Cu₅O₁₀, etc., by a superspace group approach. The compound consists of two interpenetrating subsystems of CuO₂ chains and Ca atoms. Structural parameters were refined with a superspace group of F2/m(1+α 0 γ)0s using powder X-ray and neutron diffraction data. Lattice parameters were refined to be a₁=2.8043(2) Å, b=6.3179(2) Å, c₁=10.5744(5) Å, and β₁=90.10(1)° for the [CuO₂] subsystem and a₂=3.3652(2) Å, b=6.3179(2) Å, c₂=10.5893(5) Å, and β₂=93.04(1)° for the [Ca] subsystem. Remarkable displacive modulation of the O and Ca atom sites is observed parallel to the b-axis and the c-axis, respectively. On the other hand, the Cu atom sites deviate mainly in the a direction to yield a periodic fluctuation between the nearest Cu-Cu distances. The Ca atoms suitably sit in the center of the modulated O₆ octahedra.     

Ab initio structure determination of new compound Li4CaB2O6

A new compound, Li₄CaB₂O₆, has been synthesized by solid-state reaction and its structure has been determined from powder X-ray diffraction data by direct methods. The refinement was carried out using the Rietveld methods and the final refinement converged with R_p=10.4%, R_wp=14.2%, R_exp=4.97%. This compound belongs to the orthorhombic space group Pnnm, with lattice parameters a=9.24036(9) Å, b=8.09482(7) Å, and c=3.48162(4) Å. Fundamental building units are isolated [BO₃]³⁻ anionic groups, which are all parallel to the a-b plane stacked along the c-axis. The Ca atoms are six-coordinated by the O atoms to form octahedral coordination polyhedra, which are joined together through edges along the c-axis, forming infinitely long three-dimensional chains. The Li atoms have a four-fold and a five-fold coordination with O atoms that lead to complex Li-O-Li chains that also extend along the c-axis. The infrared spectrum of Li₄CaB₂O₆ was also studied, which is consistent with the crystallographic study.     

Ruthenium(II) carbonyl complexes of P,P and P,O donor diphosphine ligands,Ph2P(CH2)nPPh2 and Ph2P(CH2)nP(O)Ph2, n = 2, 3 and their activities in catalytic transfer hydrogenation reactions

The polymeric precursor [RuCl₂(CO)₂]_n reacts with the ligands, P∩P (a, b) and P∩O (c, d), in 1:1 M ratio to generate six-coordinate complexes [RuCl₂(CO)₂(?²-P∩P)] (1a, 1b) and [RuCl₂(CO)₂(?²-P∩O)] (1c, 1d), where P∩P: Ph₂P(CH₂)_nPPh₂, n = 2(a), 3(b); P∩O: Ph₂P(CH₂)_nP(O)Ph₂, n = 2(c), 3(d). The complexes are characterized by elemental analyses, mass spectrometry, thermal studies, IR, and NMR spectroscopy. 1a–1d are active in catalyzed transfer hydrogenation of acetophenone and its derivatives to corresponding alcohols with turnover frequency (TOF) of 75–290 h^?1. The complexes exhibit higher yield of hydrogenation products than catalyzed by RuCl₃ itself. Among 1a–1d, the Ru(II) complexes of bidentate phosphine (1a, 1b) show higher efficiency than their monoxide analogs (1c, 1d). However, the recycling experiments with the catalysts for hydrogenation of 4-nitroacetophenone exhibit a different trend in which the catalytic activities of 1a, 1b, and 1d decrease considerably, while 1c shows similar activity during the second run.     

Syntheses and crystal structures of [Mg(HF)2](SbF6)2 and [Ca(HF)2](SbF6)2: new examples of HF acting as a ligand to metal centres

[Mg(HF)₂](SbF₆)₂ and [Ca(HF)₂](SbF₆)₂ monocrystals were grown from the corresponding hexafluoroantimonates(V) dissolved in anhydrous hydrogen fluoride. [Mg(HF)₂](SbF₆)₂ crystallizes in the space group Pnma (no. 62) with a=1249.1(4) pm, b=1230.2(4) pm, c=699.1(2) pm, V=1.0742(6) nm³, Z=4. Magnesium is octahedrally coordinated by six fluorine atoms from which two belong to two HF molecules. The structure can be represented by alternating rows of magnesium and antimony atoms running parallel to the c-axis. Magnesium atoms are connected by cis bridging Sb(2)F₆ units along the a-axis and by trans bridging Sb(1)F₆ units along the b-axis. In this way a three-dimensional network is formed.[Ca(HF)₂](SbF₆)₂ crystallizes in the space group P2₁/n (no. 14) with a=935.2(3) pm, b=1088.7(3) pm, c=1104.8(3) pm, β=106.697(5)°, V=1.0774(5) nm³, Z=4. The coordination sphere around the calcium atom consists of eight fluorine atoms which define the vertices of an Archimedean antiprism. The two HF molecules directly coordinate the calcium atom and their fluorine atoms are placed in the corners of different square faces of the Archimedean antiprism. The Ca-F(HF) distances are shorter than the Ca-F(Sb) distances. The Sb(1)F₆ and Sb(2)F₆ groups have four equatorial bridging fluorine atoms, while the Sb(3)F₆ groups have only two bridging trans F ligands. The Ca atoms in the [−1,0,1] plane are connected by equatorial F ligands of Sb(1)F₆ and Sb(2)F₆ units, forming a [Ca(SbF₆)⁺]_n layer. These layers are connected by trans bridging Sb(3)F₆ groups. HF molecules occupy the space between these layers and additionally contribute to the connection between the layers by hydrogen bonding.     

Photochemical reactions of chromium hexacarbonyl with tetraalkyldiphosphine disulfides

New complexes [Cr(CO)₄(R₂P(S)P(S)R₂)] and [Cr₂(CO)₁₀(-R₂P(S)P(S)R₂)] (R = Me, Et, Pr ⁿ , Bu ⁿ ), (1a)–(1d) and (2a)–(2d) [(1a), R = Me; (1b), R = Et; (1c), R = Pr ⁿ ; (1d), R = Bu ⁿ ; (2a), R = Me; (2b), R = Et; (2c), R = Pr ⁿ ; (2d), R = Bu ⁿ ] have been prepared by the photochemical reaction of Cr(CO)₆ with R₂P(S)P(S)R₂ (R = Me, Et, Pr ⁿ and Bu ⁿ ) and characterized by elemental analyses, FT-i.r., ³¹P-[¹H]-n.m.r. spectroscopy and FAB-mass spectrometry. The spectroscopic data suggest cis-chelate bidentate coordination of the ligand in [Cr(CO)₄(R₂P(S)P(S)R₂)] and cis-bridging bidentate coordination of the ligand between two metals in [Cr₂(CO)₁₀(-R₂P(S)P(S)R₂)] (R = Me, Et, Pr ⁿ and Bu ⁿ ).     

Anisotropy in the physical properties of UNiGa under high pressure

The linear thermal expansion, compressibility and magnetostriction of UNiGa have been measured under high pressure. Huge anisotropic behaviors are observed in these physical quantities. The linear thermal expansion coefficients are α _a ∼ 16·10⁻⁶ K⁻¹ along thea-axis anda _c ∼5·10⁻⁶ K⁻¹ along thec-axis, and the linear compressibilities at room temperature are κ _a ∼ 3.6·10⁻³ GPa⁻¹ and κ _c ∼ 1.7·10⁻³ GPa⁻¹ alonga-axis andc-axes, respectively. UNiGa orders antiferromagnetically belowT _N=39 K and shows a metamagnetic transition at 4.2 K in magnetic fieldB _C=1 T. It is found thatT _N decreases andB _C increases with increasing pressure.     

Ab initio structure determination of new compound Ba3(BO3)(PO4)

The crystal structure of new compound Ba₃BPO₇ was determined by ab initio method from high-resolution conventional X-ray powder diffraction data. The Rietveld refinement converged to R_p=5.92%, R_wp=8.87%, R_exp=5.00% with the following details: Hexagonal, space group P6₃mc, a=5.4898 (1) Å, c=14.7551(1) Å, Z=2. The basic unit of the structure is the [BaO₁₀]-[BO₃]-[PO₄] polar polyhedra-chain composed of Ba1-B-P-O cluster. These chains, running along c-axis, stack in a HCP mode to build the whole structure with triangular prism channels. The channels are parallel to c-axis too, in which Ba2 and Ba3 are located.