有机/无机杂化体系中聚氧化乙烯的受限结晶

通过 sol- gel技术合成了聚氧化乙烯 ( PEO)和二氧化硅 ( Si O2 )的有机 -无机杂化材料 ,通过 DSC和WAXD方法测试了杂化样品中 PEO的结晶度、结晶结构和 ( 12 0 )晶面的微晶尺寸 ,说明了 PEO在该杂化体系中的受限结晶行为

有机/无机纳米杂化材料载体化钛催化剂的聚合研究 Ⅱ.间同聚苯乙烯制备

以苯乙烯 -马来酸酐无规共聚物 ( SMA)为有机组分 ,以正硅酸乙酯 ( TEOS)为无机组分 ,利用 sol-gel方法制得纳米杂化材料 .以此为载体合成了载体化钛系催化剂 ,进行了苯乙烯聚合的研究 .聚合结果表明在50℃左右聚苯乙烯的间规度达到最大 ;随着反应温度的提高 ,分子量出现了下降现象 ,但反应活性提高 ,在70℃时 ,可达最高 1 .4 9× 1 0 6 g/( mol·h) ;并且分子量分布与文献结果相比也较宽 .

Low temperature preparation and fuel cell properties of rare earth doped barium cerate solid electrolytes

The solid electrolytes, BaCe(0.8)Ln(0.2)O(2.9) (Ln: Gd, Sm, Eu), were prepared by the sol-gel method. XRD indicated that a pure orthorhombic phase was formed at 900 degrees C. The synthesis temperature by the sol-gel method was about 600 degrees C: lower than the high temperature solid phase reaction method. The electrical conductivity and impedance spectra were measured and the conduction mechanism was studied. The grain-boundary resistance of the solid electrolyte could be reduced or eliminated by the sol-gel method. The conductivity of BaCe0.8Gd0.2O2.9 is 7.87 x 10(-2) S.cm(-1) at 800 degrees C. The open-circuit voltage of hydrogen-oxygen fuel cell using BaCe0.8Gd0.2O2.9 as electrolyte was near to 1 V and its maximum power density was 30 mW.cm(-2).

The change of Eu3+-surroundings in the system Al2O3-B2O3 containing Eu3+ ions

The change of Eu3+-surroundings with the Al/B ratio varying from 4.5 to 2 and Eu/(Al + B) = 0.02, was investigated through X-ray diffraction, infrared spectra, excitation and emission spectra, and phonon sideband. The results show coexistence of the crystal phase Al18B4O33 and the amorphous phase and Eu3+ ions of the samples with the Al/B ratio from 3 to 2 are incorporated into the amorphous phase. It was also found that electron-phonon coupling strength decreases with the Al/B ratio from 3 to 2, non-radiative decay rate decreases, resulting in an increase of the Eu3+-emission intensity. (C) 1999 Elsevier Science Ltd. All rights reserved.

溶胶-凝胶生物传感器

评述了溶胶-凝胶(sol-gel)生物传感器这个领域已取得的成果,主要内容涉及溶胶-凝胶固定化方法的过程、优点与性质,溶胶-凝胶光学生物传感器和安培生物传感器的发展,并展望了其发展趋势.

溶胶-凝胶法光功能材料研究进展

本文对sol-gel法制备光功能材料及其材料的特性进行了介绍，对有机染料和无机分子掺杂于sol-gel基质中的激光性质、发光性质、光致变色现象及量子尺寸效应等进行了综述，并预测了sol-gel法制备光功能材料的发展趋势。

荧光素掺杂的TiO_2凝胶的制备及光谱研究

近些年来，溶胶－凝胶(Sol-Gel)方法作为一种软化学合成方法具有很多优点［1］，例如制作简单、烧结温度低，制得样品稳定、坚韧，制备灵活性高等。作为一种常用的染料，荧光素(FL)常用于研究非线性光学。利用Sol-Gel法可以很好地将染料分子固定在光…

Preparation and luminescent properties of inorganic polymer nano - Structured hybrid films doped with rare earth complexes

The inorganic/polymer hybrid films with good luminescent properties have been obtained by the sol - gel process via incorporating the polymer component doped with rare earth complexes. These films exhibit good toughness and transparency. Their fluorescence spectra and lifetimes indicate that they all have the characteristic luminescence of the central rare earth ions. The lifetimes of these films are longer than those of pure complexes. TEM have showed that the rare earth complexes are dispersed homogeneously in SiO2/PVB interpenetratiny networks, and the dispersed size is between 20 and 30 nn.

Isobutane/butene alkylation over supported heteropoly acid catalysts: I. Influence of the structure of silica

Catalysts consisting of heteropoly acids (HPAs) supported on different silica and mesoporous molecular sieves have been prepared by impregnation and the sol-gel method, respectively, and their catalytic behavior in fixed-bed alkylation of isobutane with butene has been investigated. The activity, selectivity and stability of the supported-HPA catalysts could be correlated with the surface acidity of the catalysts, the structure of supports as well as the time on stream (TOS). In the fixed-bed reactor, the acidity of the heteropoly acid is favorable to the formation of dimerization products (C-8(=)); especially, the pore size of supports was seen to have an important effect on activity and product distribution of the catalysts. Contrary to the traditional solid-acid catalysts, the supported-HPA catalysts own an excellent stability for alkylation, which makes it possible for these supported catalysts to replace the liquid-acid catalysts used in industry.

Luminescence properties of rare earth (Eu3+ and Tb3+) complexes with conjugated carboxylic acids and 1,10-phenanthroline incorporated in silica matrix

Binary and ternary complexes of europium and terbium with conjugated carboxylic acid (nicotinic acid and 3,4-furandicarboxylic acid) and 1,10-phenanthroline were introduced into silica gel by the sol-gel method. The luminescence behavior of the complexes in silica gels was studied compared with the corresponding solid state complexes by means of emission, excitation spectra and lifetimes. The result indicated that the rare earth ions (EU3+ and Tb3+) showed fewer emission lines and slightly lower emission intensities in the silica gel than those in pure rare earth complexes. The lifetimes of rare earth ions (EU3+ and Tb3+) in silica gel doped with rare earth complexes became longer than those in pure rare earth complexes. (C) 1998 Elsevier Science S.A.

溶胶—凝胶技术在功能材料制备中的应用

引言溶胶—凝胶(Sol-gel)技术作为在低温和温和条件下合成无机化合物或制备无机材料的重要方法,具有许多独特的优点:(1)由于在溶胶—凝胶法中所用的原料首先被分散在溶剂中而形成低粘度的溶液,因此就可以在很短的时间内获得分子水平上的均匀性。在形成凝胶时,反应物之间也是在分子水平上被均匀地

STUDY ON THE NON-STIOCHIOMETRIC SNO2-X NANOCRYSTALLINE MATERIAL BY XRD, XPS AND ESR

Nonstiochiometric SnO2-x nanocrystalline material were successfully prepared through Sol-Gel process using anhydrous stannic chloride and iso-propyl alcohol. TEM observation shows that the mean diameter of the powder sintered at 700 degrees C for 2 hours is about 20 nm. By the investigation of XRD and ESR, we can conclude that the sample sintered at 300 degrees C for 2 hours was amorphous and it grew into nanocrystalline with the oxygen vacancies and defects when sintered at 700 degrees C for 2 hours. Using these conclusion, the ESR signals and the difference between the two SnO2-x samples are explained.

SYNTHESIS AND PROPERTIES OF LAFEO3 ULTRAFINE POWDERS

The ultrafine LaFeO3 with particle size of 12 similar to 75nm was prepared by sol-gel method. In the process of gel to ultrafine powder, the weight loss reached 90%. The lowest forming temperature of single phase crystalline LaFeO3 ultrafine powder was ob

La_2CuO_4超微粉末的合成及电性质研究

本文用Sol-Gel法合成了La_2CuO_4超微粉末,X-ray衍射分析表明,在600℃已生成纯相的La_2CuO_4超微粉末;不同温度焙烧时,结构未变,均属于正交晶系。实验发现,La_2CuO_4的平均粒径随焙烧温度的增加而明显地增大。研究了La_2CuO_4的电阻率随粒径的变化,发现La_2CuO_4的电阻率随粒径的增加而减小。

可见光响应光催化剂K4Ce2M10O30（M=Ta, Nb）及其光解水特性的研究

氢能已被广泛认为是最具有潜力解决能源危机和环境问题的理想替代能源之一，其开发备受各个领域科学家的重视，更是从根本上解决环境地球化学工作者的主要目标：对已被破坏的环境和生态进行修复以及对可能破坏环境与生态的人类活动进行干预和指导。在众多的氢能开发手段中，利用太阳能光催化分解水制取氢气是一种兼顾能耗、资源和环境的最为理想和最有前途的氢能开发手段之一。在光催化分解水过程中，最为首要的研究内容就是开发具有适宜能带结构能响应可见光，稳定地、高量子效率地光解水的固相半导体光催化剂。 本论文中，通过高温固相反应合成了呈四方晶系钨青铜结构的半导体光催化剂K4Ce2M10O30(M=Ta, Nb)，吸收边分别达到580 nm (M＝Ta) 和690 nm (M＝Nb)，对应带隙为2.2 eV和1.8 eV。可见光下（λ> 420 nm）光催化分解H2O产生H2和O2的活性表明它们不仅有适宜的带隙响应可见光，并且其价带和导带位置能满足完全分解水的电化学电位需要。在担载Pt、RuO2以及NiO（NiOx）等助催化剂对产氢性能有显著的提高。同时以乙醇钽和草酸铌可溶性前驱体，分别通过溶胶凝胶法（Sol-gel）和聚合物络合法(Polymerizable Complex)制备了K4Ce2Ta10O30和K4Ce2Nb10O30。通过湿法化学合成的光催化剂显示了更高的光催化活性，并且通过PC法制备的K4Ce2Nb10O30更是实现了在大于300 nm 的光辐射下完全分解纯水产生摩尔比为约2:1 的H2和O2。 通过高温固相反应得到Nb取代K4Ce2Ta10O30中部分晶格Ta形成的单相无限固溶体系列K4Ce2Ta10-xNbxO30（x=0~10）是结构一致的同系物，吸收边介于540 nm～710 nm 之间，并且随着x的增加，吸收边依次红移，光催化产氢活性依次降低，但是x=2，5，8时的产氧活性比x=0和10的高，光催化活性的差异主要源于它们光吸收特性和能带结构的差异。基于密度范函理论DFT的第一性原理计算结果表明，光催化剂K4Ce2M10O30(M=Ta, Nb)的能带结构为：导带主要由Ta 5d (Nb 4d)组成，处于高能级的电子未占据态的Ce 4f 与其有很明显的重迭，但由于其高度局域特性，不能很好地参与光生电子在导带的传导，从而其对光催化活性的贡献很小，而价带则由O 2p与Ta 5d (Nb 4d)以及电子占据态的Ce 4f杂化轨道组成。同时通过高温固相反应合成了系列含稀土元素的光催化剂K4Re2M10O30(Re=La, Ce, Nd, Sm, Y; M=Ta, Nb)，通过对它们及其前驱体氧化物的光吸收特性以及电子结构的第一性原理计算研究，合理的解释了只有当Ln＝Ce时才具有可见光响应特性的微观机理。