空气中合成M2B4O7:Eu3+(M=Na,K)荧光体及其性质表征

以M2B4O7(M=Na,K)为基质,在空气中掺杂稀土元素Eu3+得到了Na2B4O7:Eu3+和K2B4O7:Eu3+荧光体.探讨了体系的烧结条件和荧光性质,分析了晶体的结构.结果表明,虽然两种体系的最佳合成条件不同,但是体系中都同时存在[BO4]和[BO3]结构;稀土离子Eu3+的发光以电偶极跃迁5D0-7F2为主,处于非中心对称的格位上,并且可以很好地存在于基质中,Na2B4O7:Eu3+具有较强的发光强度.     

Co~(2+)掺杂的纳米TiO_2薄膜光催化特性及电化学阻抗谱研究

本文采用交流电沉积技术,在多孔氧化铝模板中合成出Co2+掺杂的纳米TiO2薄膜(Co2+/TiO2薄膜)。以次甲基蓝为降解物,研究了纳米Co2+/TiO2薄膜在可见光下的催化性能,考察了阳极偏压对光催化活性的影响。用电化学阻抗谱(EIS)研究了纳米Co2+/TiO2薄膜在次甲基蓝溶液中的电化学行为,给出了相应的等效电路和半导体能带结构参数-空间电荷层宽度。研究表明,适量Co2+掺杂可以提高TiO2薄膜的光催化活性。在Co2+/TiO2膜电极上施加一定阳极偏压,使空间电荷层宽度增加,因此能有效实现光生电子-空穴分离,进一步提高次甲基蓝的光催化降解效率。     

催化光度法测定痕量钴的研究

研究了钴 (Ⅱ )离子在碱性介质中催化H2 O2 氧化 2 ,2′ 二甲基 4 ,4′ 二氨基联苯 (o Tolidine)的显色反应 ,发现当Co2 +浓度在 0 8～ 3 6ng mL时具有强烈的催化显色作用 ,而当Co2 +浓度在 0 0 4～0 2 4 μg mL时则对显色作用具有抑制效应。基于此研究了测定痕量Co(Ⅱ )离子的影响因素 ,建立了测定痕量Co2 +离子的催化光度法。测定的线性范围Co(Ⅱ )的浓度在 0 0 4～ 0 2 4 μg mL时 ,灵敏度为 3 1 6× 1 0 -6g L ;Co(Ⅱ ) 0 8～ 3 6ng mL时 ,灵敏度为 1 78× 1 0 -6g L。实验操作简便 ,应用于工业污水中痕量Co2 +离子的监测 ,结果满意。     

Sr2CeO4∶Eu3+柠檬酸-凝胶法的合成及发光性质研究

柠檬酸-凝胶方法促使多离子在分子水平上混合，与固相烧结方法相比，能够降低烧结温度和烧结时间。利用这种方法在1000℃下很短的时间得到单相化合物Sr₂CeO₄。Sr₂CeO₄是一种发出很强蓝光的基质发光材料。为寻找新的发光体，我们将稀土离子Eu³⁺掺杂在其中，从荧光光谱上可以看出存在从基质向稀土离子的能量转移。Sr₂CeO₄∶Eu³⁺的发光颜色可调谐，当Eu³⁺离子浓度较小(< 0.5mol%)时，体系发出很强的白光;当Eu³⁺离子浓度较大(>10mol%)时，体系发出很强的红光，并且猝灭浓度高。     

Y2O3∶Eu3+发光薄膜的溶胶-凝胶法制备、表征及图案化

采用Pechini溶胶-凝胶法制备了纳米级Y2O3∶Eu3+发光薄膜, 同时, 通过软石印技术得到了条纹宽度为5～60 μm的Y2O3∶Eu3+图案化发光薄膜. 通过X射线衍射 (XRD)、付里叶变换-红外光谱 (FT-IR)、原子力显微镜(AFM), 光致发光(PL)光谱及寿命等方法对得到的发光薄膜进行了表征. XRD结果表明500 ℃时薄膜开始结晶, 900 ℃已结晶完全, 得到了立方相的产物. 图案化的条纹在烧结的过程中发生了明显的收缩(50%). Y2O3基质向掺杂的稀土离子Eu3+发生了有效的能量传递, 使得Eu3+显示出5D0-7FJ(J=0, 1, 2, 3, 4)特征发射. 寿命和光致发光光谱的研究表明, 发光强度随着温度的升高而增强.     

自组装DNA与[Co(phen)3]2+/3+相互作用的表面增强拉曼光谱法研究

对金基体上自组装ssDNA及dsDNA与钴邻菲啉配合物离子([Co(phen)3]2+/3+)相互作用进行电化学现场表面增强拉曼光谱(SERS)研究,获得相互作用位点及相互作用模式的信息.dsDNA与[Co(phen)3]2+/3+存在一定的嵌插作用,即配合物通过配体邻菲啉(phen)环以嵌插模式结合在碱基A-T及G-C富集区,同时与磷酸二酯键PO2结合,并伴随dsDNA螺旋构象由B型向A型转变;而[Co(phen)3]2+/3+则是以静电模式与ssDNA的磷酸二酯键PO2及脱氧核糖组成的骨架相互作用.     

层状化合物La2Ni1-yCoyO4+δ的合成、结构与性能

采用氨基多羧酸配合物法合成La2Ni1-yCoyO4+δ(y=0~0.2)超细粉料, 研究陶瓷样品的结构和混合导电性能. 研究结果表明, La2Ni1-yCoyO4+δ具有正交结构(Fmmm空间群), Co离子取代增加了钙钛矿层中ab平面上Ni/Co—O键的键长、岩盐层中沿c 轴方向上La—O键的键长和非化学计量氧含量, 并有利于改善材料的烧结性能. 随着Co离子含量的增加, 总电导率的峰值温度向高温移动, 高温段总电导率随温度的变化趋于平缓, 但总电导率水平出现降低; 增加Co离子含量还有利于提高氧离子导电性能. Co离子取代对陶瓷样品混合导电性能的影响与晶体结构参数的变化紧密相关.     

乙醇-硫酸铵双水相萃取镉-碘化钾-罗丹明B离子缔合物

研究了在(NH4)2SO4存在下,碘化钾-罗丹明B-乙醇体系萃取Cd(Ⅱ)的行为及最佳分相条件。实验表明,在pH 1～3时,乙醇-(NH4)2SO4双水相体系对[CdI4]2-络阴离子的萃取率只有35.5%;加入罗丹明B后,该体系能完全萃取镉-碘化钾-罗丹明B形成的离子缔合物,而干扰离子Zn2+、Fe3+、Co2+、Cu2+、Ni2+不被萃取,实现Cd2+与上述离子的分离。     

Sb掺杂ZTO透明导电薄膜的结构和性能

采用溶胶凝胶法和旋涂法制备Sb掺杂钙钛矿结构ZTO(ZnSnO_3)透明电薄膜,并借助XRD、SEM、XPS、UV-Vis和Hall效应测试等手段研究了其结构和性能。比较了Sb离子单独置换ZnSnO_3晶体中的Zn2+或Sn4+,以及同时置换Zn2+和Sn4+等3种置换方式所得薄膜的结晶状态,分析了不同置换方式形成的薄膜中Sb离子实际占有的晶格位置,以及Sb5+与Sb~(3+)的比例变化。探讨了不同置换方式晶体中氧空位(VO)、锌间隙(Zni)和锡离子变价(SnSn″)等结构缺陷相应的含量变化,并研究Sb离子掺杂浓度对薄膜晶体结构、结构缺陷和电阻率的影响。研究表明,3种置换方式的Sb掺杂ZTO薄膜均保持单一ZnSnO_3晶相,并且Sb离子均按设计的方案进入了相应的晶格位置,但不同置换方式的薄膜中,Sb5+与Sb~(3+)的比例不同,并且会随Sb离子浓度增大而逐渐减小。研究证明Sb离子置换方式以及掺杂浓度均会显著影响薄膜中载流子的浓度和迁移率,从而影响其电性能。在所制备的薄膜中,Sb离子单独置换Zn2+且组成为Sb_(0.15)Zn_(0.35)Sn_(0.5)O_(1.5)的薄膜电阻率最低,为0.423Ω·cm。此外,所有Sb掺杂ZTO薄膜在360~800 nm波长范围内透过率均在78%以上。     

Li2O-Na2O-B2O3-SiO2烧结助剂对BaAl2Si2O8陶瓷结构与介电性能的影响

采用传统固相反应工艺,按化学计量比合成BaO-Al_2O3-SiO_2(BAS)-x%(w/w) Li_2O-Na_2O-B_2O3-SiO_2(LNBS)(x=0,1,2,3,4)陶瓷。研究不同LNBS烧结助剂添加量对BAS系微波介质陶瓷的结构和介电性能的影响。通过Clausius-Mossotti公式计算讨论了BAS理论与实验介电常数(εr)的差异。研究结果表明:LNBS烧结助剂中Li+进入钡长石Al3+位或单四元环(S4R)间隙,并产生了O_2-空位或Ba2+空位,从而促进BAS六方相向单斜相的转变。添加适量的LNBS烧结助剂后,BAS陶瓷的烧结温度从1 400℃降低到1 325℃,同时BAS陶瓷样品密度、品质因数(Qf)值以及频率温度系数(τf)得到改善。当x=1,烧结温度为1 325℃时,可获得综合性能相对较好的BAS陶瓷,其介电性能:Qf=35 199 GHz,εr=6.37,τf=-1.613×10-5℃-1。     

Atomic Layer Deposition of Cobalt Phosphide for Efficient Water Splitting

Transition‐metal phosphides (TMP) prepared by atomic layer deposition (ALD) are reported for the first time. Ultrathin Co‐P films were deposited by using PH₃ plasma as the phosphorus source and an extra H₂ plasma step to remove excess P in the growing films. The optimized ALD process proceeded by self‐limited layer‐by‐layer growth, and the deposited Co‐P films were highly pure and smooth. The Co‐P films deposited via ALD exhibited better electrochemical and photoelectrochemical hydrogen evolution reaction (HER) activities than similar Co‐P films prepared by the traditional post‐phosphorization method. Moreover, the deposition of ultrathin Co‐P films on periodic trenches was demonstrated, which highlights the broad and promising potential application of this ALD process for a conformal coating of TMP films on complex three‐dimensional (3D) architectures.     

Plasma-enhanced atomic layer deposition of Co using Co(MeCp)2 precursor

Cobalt (Co) thermal or plasma enhanced atomic layer deposition (PE-ALD) was investigated using a novel metal organic precursor, Co(MeCp)₂, and NH₃ or H₂ or their plasma as a reactant. The growth characteristics, electrical and microstructural properties were investigated. Especially, PE-ALD produced Co thin films at low growth temperature down to 100 °C. Interestingly, the low temperature growth of Co films showed the formation of columnar structure at substrate temperature below 300 °C. The growth characteristics and films properties of PE-ALD Co using bis(η-methylcyclopentadienyl) Co(II) (Co(MeCp)₂) was compared with those of PE-ALD Co using other Cp based metal organic precursors, bis-cyclopentadienyl cobalt (II) (CoCp₂) and cyclopentadienyl isopropyl acetamidinato-cobalt (Co(CpAMD)).     

Preparation and characterization of organic–inorganic hybrids and coating films from 3‐methacryloxypropylpolysilsesquioxane

3‐Methacryloxypropylpolysilsesquioxane (MA‐PS) was prepared by acid‐ or base‐catalyzed hydrolytic polycondensation of 3‐methacryloxypropyltrimethoxysilane (MAS). MA‐PS coating film was prepared by dip‐coating on organic, metal and inorganic substrates, including poly(ethylene terephthalate), aluminum, stainless steel, and glass. The coating films on poly(ethylene terephthalate) and glass showed high adhesive strength. The hardness of coating films increased with increasing heat treatment temperature, whereas they decreased with increasing H₂O/MAS molar ratio. The refractive index of coating films increased with increasing heat treatment temperature. In addition, flat and transparent free‐standing films (0.24–0.27 mm thickness) were prepared from MA‐PS that were crack‐free after heat treatment at 1000 °C. Copyright © 2001 John Wiley & Sons, Ltd.     

Embedded silver ions-containing liposomes in polyelectrolyte multilayers: cargos films for antibacterial agents

A new antibacterial coating made of poly(L-lysine)/hyaluronic acid (PLL/HA) multilayer films and liposome aggregates loaded with silver ions was designed. Liposomes filled with an AgNO 3 solution were first aggregated by the addition of PLL in solution. The obtained micrometer-sized aggregates were then deposited on a PLL/HA multilayer film, playing the role of a spacer with the support. Finally, HA/PLL/HA capping layers were deposited on top of the architecture to form a composite AgNO 3 coating. Release of encapsulated AgNO 3 from this composite coating was followed and triggered upon temperature increase over the transition temperature of vesicles, found to be equal to 34 degrees C. After determination of the minimal inhibitory concentration (MIC) of AgNO 3 in solution, the antibacterial activity of the AgNO 3 coating was investigated against Escherichia coli. A 4-log reduction in the number of viable E. coli cells was observed after contact for 120 min with a 120 ng/cm (2) AgNO 3 coating. In comparison, no bactericidal activity was found for PLL/HA films previously dipped in an AgNO 3 solution and for PLL/HA films with liposome aggregates containing no AgNO 3 solution. The strong bactericidal effect could be linked to the diffusion of silver ions out of the AgNO 3 coating, leading to an important bactericidal concentration close to the membrane of the bacteria. A simple method to prepare antibacterial coatings loaded with a high and controlled amount of AgNO 3 is therefore proposed. This procedure is far superior to that soaking AgNO 3 or Ag nanoparticles into a coating. In principle, other small bactericidal chemicals like antibiotics could be encapsulated by this method. This study opens a new route to modify surfaces with small solutes that are not permeating phospholipid membranes below the phase transition temperature.     

Synthesis, characterization and some properties of novel bis(pentafluorophenyl)methoxyl substituted metal free and metallophthalocyanines

The preparation of some new tetrakis[bis(pentafluorophenyl)methoxyl] substituted metal free and metallophthalocyanine (MPcs) complexes were achieved by the tetramerization of 4-[bis(pentafluorophenyl)methoxy]phthalonitrile with Li metal in pentan-1-ol or metal [Co(II) or Zn(II)] acetates in DMAE, respectively. The structures of the target compounds were confirmed by elemental analysis, IR, UV–vis, ¹H NMR, ¹⁹F NMR and mass spectroscopic methods. MPcs are soluble only in strong and medium polar solvents while the metal free one is soluble in weakly, medium and strong polar solvents. The temperature and frequency dependence of the electrical conductivities were studied on spin coated films of the compounds using dc and impedance spectroscopy techniques in the frequency range from 40 to 10⁵ Hz and within the temperature range from 290 to 440 K. The temperature dependence of the exponent s and conductivity, σ_ac, were completely in agreement with the prediction of the hopping model. The redox properties of the complexes were determined by cyclic voltammetry. The nature of the redox processes was also confirmed using spectroelectrochemical measurements.     

析氯钛基RuO_2－Co_3O_4－TiO_2（60）涂层的研究

用稳定极化、Ｘ射线衍射、透射电镜和扫描电镜的方法研究了钛基ＲｕＯ_２－Ｃｏ_３Ｏ_４－ＴｉＯ_２（６０）涂层的析氯活性、导电性、使用寿命、微观结构和表面形貌。并对其活性表面积进行了评价。详细讨论了涂层成份、微观结构和表面形貌对涂层析氯活性和活性表面积的影响。发现在０～１０ｍ／ｏＣｏ_３Ｏ_４和６０ｍ／ｏＴｉＯ_２成份范围内ＲｕＯ_２、Ｃｏ_３Ｏ_４和ＴｉＯ_２可形成单一金红石型固溶体,且有优异的析氯活性、电导率和使用寿命。以此研究为基础可改进氯碱工业广泛使用的传统ＲｕＯ_２－ＴｉＯ_２阳极,降低阳极涂层中贵金属含量,提高阳极的电化学性能．     

Formation of YBa2Cu408 Thick Films via Spray Pyrolysis

Thick films of YBa₂Cu₄O₈ superconductor were prepared by a spray-pyrolysis coating technique using silver strip as the substrate. The precursor solution consisted of metal nitrates dissolved in a mixture of ethandiol and water. The solution was nebulized onto the heated substrates to obtain films as-deposited. The temperature of deposition had a great effect on the morphology of the film. Sintering the films in flowing oxygen at 810 °C for 60 h yielded films with T_c(onset) = 82.0 K and T_c(zero) = 74.6 K. Films were characterized by x-ray diffraction, scanning electron microscopy, transport and magnetic measurements.     

Stepwise self-assembly of ordered supramolecular assemblies based on coordination chemistry

Ultrathin multilayers based on transition metal complexes have been prepared by successive deposition and self-assembly. Dendrimer layers were deposited onto SiO2 wafers by alternately immersing the substrate into a solution of terpyridyl (tpy)-pendant poly(amido amine) (PAMAM) dendrimers (dend-n-tpy; n = 8, 16) dissolved in CH2Cl2, followed by the interfacial coordination reaction with cobalt (Co2+) from aqueous solution. The films derived from this simple assembly method have been characterized by electrochemical methods, synchrotron-based X-ray reflectivity (XRR), and X-ray fluorescence (XRF) recorded under grazing incidence. XRR analysis revealed a linear thickness dependence with an increase of 9.9 +/- 0.5 angstroms and 10.8 +/- 0.4 angstroms per growth cycle for both dend-8-tpy and dend-16-tpy, respectively, indicative of a layer-by-layer (LbL) growth of single dendrimer/Co2+ layers. XRF and electrochemical results showed that the amount of Co2+ increases linearly as more layers are deposited, and that the Co2+ concentration (mol/L) in dend-8-tpy/Co2+ films decays slowly as the number of growth cycles (l) increases. Moreover, a preliminary kinetics analysis indicated that the growth of a dendrimer layer in a deposition cycle is a self-limiting process.     

One-step synthesis of stoichiometrically defined metal oxide nanoparticles at room temperature

A great variety of metal oxide nanoparticles have been readily synthesized by using alkali metal oxides, M(2)O (M is Na or Li) and soluble metal salts (metal chlorides) in polar organic solutions, for example, methanol and ethanol, at room temperature. The oxidation states of the metals in the resulting metal oxides (Cu(2)O, CuO, ZnO, Al(2)O(3), Fe(2)O(3), Bi(2)O(3), TiO(2), SnO(2), CeO(2), Nb(2)O(5), WO(3), and CoFe(2)O(4)) range from 1 to 6 and remain invariable through the reactions where good control of stoichiometry is achieved. Metal oxide nanoparticles are 1-30 nm and have good monodispersivity and displayed comparable optical spectra. These syntheses are based on a general ion reaction pathway during which the precipitate occurs when O(2-) ions meet metal cations (M(n+)) in anhydrous solution and the reaction equation is M(n+) + n/2 O(2-) --> MO(n/2) (n=1-6).     

Following the growth of surface films on lithium and their thermal behavior in standard LiPF6 solutions using differential scanning calorimetry

In this paper, we report on attempts to use differential scanning calorimetric measurements of aged Li electrodes for the study of the kinetics of the growth of surface films on the active metal. Standard, commonly used alkyl carbonate solutions such as ethylene and di-methyl carbonates with LiPF6 were explored. Heating Li samples in solutions after aging by DSC, resulted in well-resolved curves of reaction heats vs temperature. Exothermic reactions occurring at temperatures below 150 degrees C could be attributed to changes related to the surface films and their heat evolved, increased as a function of storage time, and hence these heats represent the thickness of the surface films that grow upon storage. Scanning electron microscopy of the Li surfaces as a function of storage and heating to different temperatures confirmed that the thermal reactions of Li surfaces in these solutions up to 150 degrees C relate to the surface films only. XPS studies revealed that these processes of the surface films change the metastable organic Li salts to more stable inorganic compounds such as LiF and Li2O. Massive red-ox reactions, between the salt anion and the solvents and between the solution species and the active metal, occur at temperatures higher than 150 degrees C. The kinetics of growth of the surface films on Li show an inverse logarithmic behavior, expected for thin surface films with which the rate-limiting step of their growth depends on ions transport across the film.