掺杂C60的SiO2—PDMS有机—无机复合材料的光学性质

用溶胶－凝胶法制备了含了C60的二氧化硅－聚二甲基硅氧烷复合凝胶材料，研究了材料的制备机理及结构性质，及其在低温条件下的变温发光光谱，给出了发光强度与温度的变化关系曲线，拟合实验数据得到了C60／SiO2-PDMS热激活能为450cm^-1.     

水热-溶胶-凝胶法制备钠离子电池正极材料Na_3V_2(PO_4)_3/C及其性能研究

分别采用溶胶凝胶法和水热-溶胶-凝胶法合成了钠离子电池正极材料Na_3V_2(PO_4)_3/C。用XRD、SEM、恒流充放电等对样品进行了表征。研究表明,两种方法合成的Na_3V_2(PO_4)_3/C样品均为纯相,呈多孔状结构,采用水热-溶胶-凝胶法制备出的Na_3V_2(PO_4)_3/C样品颗粒尺寸更小,更有利于钠离子脱嵌,有利于提高材料的电化学性能。溶胶-凝胶法制备的样品在0.1和2C倍率下首次放电比容量为98.3和31.3mAh/g,水热-溶胶-凝胶法制备的样品在0.1和2C倍率下首次放电比容量高达111.9和94.1mAh/g,电化学性能得到明显改善。     

溶胶-凝胶法制备有机-无机杂化光波导材料研究进展

有机-无机杂化材料因同时具有有机功能基团和无机功能基团的结构特点而易于有机光活性物质和无机活性物质的掺杂已被人们广泛关注和大力研究.溶胶-凝胶法是制备有机-无机杂化光波导材料的主要方法.阐述了溶胶-凝胶法制备杂化材料的原理,比较了几种目前研究得较多的有机-无机杂化光波导材料体系,指出了各自的优缺点,介绍了杂化材料制备光波导器件的工艺流程,最后归纳了溶胶-凝胶法制备有机-无机杂化光波导材料过程中存在的问题.     

聚乙二醇对磷酸铁锂形貌及电化学性能的影响

采用溶胶-凝胶法制备了LiFePO4。研究了聚乙二醇对LiFePO4材料形貌和电化学性能的影响。结果表明,添加聚乙二醇制备的材料具有更小的粒径,更大的比表面积;该材料以0.2C、1C、5C、10C的倍率放电,首次放电比容量分别达到143.9mAh/g、133.4mAh/g、124.2mAh/g、112.7mAh/g,比没添加聚乙二醇制备的材料具有更好的倍率性能。     

碳/掺杂碳气凝胶及其研究进展

经溶胶-凝胶、超临界干燥和高温碳化过程制备的碳气凝胶及通过掺杂获得的掺杂碳气凝胶是一种新型的轻质纳米多孔材料,具有许多优异的性能和广阔的应用前景.介绍了溶胶-凝胶法的反应机理,综述了碳/掺杂碳气凝胶的制备方法、发展现状,指出了目前存在的问题并提出了新的可行的制备掺杂碳气凝胶的方法.     

锂离子电池LiFePO4新型合成方法及改性研究

采用乙醇体系的溶胶-凝胶法制备了LiFePO4,通过Mg2 掺杂对其进行了改性,最后以葡萄糖为碳源,制备了不同含碳量的Li0.98Mg0.01FePO4/C复合材料.采用X射线衍射、扫描电子显微镜表征了材料的微观结构,对材料进行了电化学性能测试.结果表明,在Mg2 掺杂产物中,Li0.98Mg0.01FePO4在0.1C下首次放电比容量高达140.1mAh·g-1;Li0.98Mg0.01FePO4/C复合材料中,含碳量为6%的材料性能最佳,尤其是高倍率放电性能有显著提高.     

银基电接触材料的应用研究及制备工艺

鉴于银基电接触材料在电力系统、电器工业中的重要性,综合近年多种文献资料,阐述了Ag/Ni、Ag/C、Ag/WC和Ag/MeO等4个主要系列的银基电接触材料的特点.分析了喷射沉积法、溶胶-凝胶法、纤维强化法、等静压制法、等离子体喷涂法等制备银基电接触材料的工艺特点.结合现阶段研究工作,研制和改进电接触材料的制备工艺,发展新型环保触头材料、多相复合触头材料及纳米触头材料是今后银基电接触材料发展的主要方向.     

层状硅酸盐制备多孔材料的研究进展

利用层状硅酸盐制备多孔材料是多孔材料发展的新趋势.介绍了层状多孔材料的主要用途,以及水热合成法、柱撑法、溶胶-凝胶法和室温酸法等多孔材料制备技术,阐述多孔材料的合成机理,并指出层状硅酸盐制备多孔材料的发展前景.     

氧化碲非线性光学材料的研究进展

综述了氧化碲非线性光学材料(包括纯TeO_2材料和掺杂有其它物质的氧化碲基材料)的制备方法、国内外研究进展,探讨了分子结构对氧化碲基材料非线性光学性的影响,分析了采用高温熔融法和溶胶-凝胶法制备氧化碲非线性光学材料的优缺点,展望了氧化碲材料的应用前景.指出高温熔融法或溶胶-凝胶法与其他制备方法,如超声、光聚合、电化学等相结合是制备优异氧化碲非线性光学材料的有效手段.     

超级电容器MnO2/CRF复合电极材料的制备及性能的研究

以间苯二酚(R)和甲醛(F)为原料,碳酸钠(C)为催化剂,制备碳气凝胶(CRF),并以KMnO4和Mn(CH3COO)2·4H2O为原料,采用了化学沉淀法制备MnO2/CRF复合材料.用N2吸附、X射线衍射(XRD)和扫描电镜(SEM)对所制备的MnO2、CRF和MnO2/CRF复合材料进行了表征,结果表明碳气凝胶具有珍珠串式的无序多孔网络结构,所制备的MnO2为纳米级颗粒,复合材料为纳米级粉体.并对不同配比的MnO2/CRF复合材料的电化学性能进行了研究.循环伏安、恒流充放电实验表明了所制备的MnO2/CRF复合电极材料具有良好的可逆性和充放电性能.当MnO2含量为60%时,MnO2与碳气凝胶复合制成的新型电极材料具有226.3F/g的比电容,比碳气凝胶电极的比电容提高了1倍.此外,对复合电极的循环寿命进行了研究,表明复合电极具有良好的循环充放电性能.     

Fullerenol-containing Materials Derived by Sol-gel Processing

Water soluble fullerenols were synthesized and incorporated in SiO2, SiO2-TiO2, GPTMS-SiO2, GPTMS-ATPS inorganic and organic-inorganic materials by sol-gel processes. The maximum concentrations of C60(OH)n and C70(OH)n in the obtained SiO2 gels were estimated to be about 0.6% and 1.5% in weight, respectively. The characteristics of the UV/visible spectra of fullerenols in H2O and various gels were measured and compared. The thermal stability of fullerenols in gels was investigated with differential thermal analysis (DTA). The results indicate that the absorption features of fullerenols in solid gels are similar to those in H2O and the fullerenols in SiO2 are stable at 400℃. The optical limiting effect of the fullerenols was investigated preliminarily.     

SiO2/SnO2复合凝胶对丙酮和氨气的吸附动力学研究

应用溶胶－凝胶法制备了SiO2/SnO2复合凝胶，测定了红外光谱，采用静态吸附法测定了不同组成的SiO2/SnO2复合凝胶对丙酮气体和氨气的吸附动力学曲线。结果表明，SiO2与SnO2凝胶的复合有利于气体的吸附，在凝胶中含有一定的羟基是吸附性强的根源。数据拟合得到的吸附动力学方程分别为x=c1(1-exp(-c2t)和x=c′1t/(1 c2′t)的形式，说明SiO2/SnO2复合凝胶对丙酮气体和氨气的吸附机理分别具有单活性位和双活性位吸附特征。     

Quantitative chemical state analysis of supported vanadium oxide catalysts by high resolution vanadium kα spectroscopy

Oxidation states of vanadium species on Al(2)O(3), SiO(2), and TiO(2) were quantitatively analyzed by least-squares fitting of V Kα spectra recorded with a two-crystal X-ray fluorescence spectrometer. Uncertainties of analytical results by the normalization procedure, and coefficient of validation and the reduction behavior of vanadium species by X-ray irradiation were discussed. The V(5+)/V(4+)/V(3+) ratios on Al(2)O(3), SiO(2), and TiO(2) calcined at 773 K in air were determined to be ca. 6/3/1, 3/6/1, and 5/4/1, respectively. The possible chemical states of vanadium species on supports were proposed.     

Fabrication of silica/PDMS hybrid nanoparticles by a novel solvent adjustment route

The silica/polydimethylsilane (PDMS) hybrid nanoparticles were successfully synthesized by a novel solvent adjustment route. The as-prepared hybrid nanoparticles were characterized by transmission electron microscopy, UV-vis spectra, and IR spectra. The possible mechanism for the formation of silica/PDMS nanoparticles was discussed. The adjustment of solvents is a very important factor since it could tune the surface ligands and improve the coordination ability. On the other hand, it could also tune the interaction between precursors, intermediate or the target hybrid materials and guarantee the monodispersion of prepared nanoparticles. With the merits of PDMS and silica, the as-prepared SiO2-PDMS hybrid nanoparticles have a good application in hard coating material.     

Si和C共掺杂的SiO2薄膜的光致发光

采用双离子束溅射技术制备了Si和C共掺杂的SiO2薄膜,在N2气氛下进行了不同温度的退火处理。分析了样品在室温下的光致发光(PL)特性,在该样品中观察到分别位于410nm和470nm的两个发光峰。这两个发光峰的强度随着退火温度的变化呈现不同的变化趋势,表明两个发光峰的来源并不相同。用XRD和FTIR测试手段分析了样品的结构,认为470nm的发光来源于中性氧空位缺陷(O3≡Si～Si≡O3),而410nm的发光来源于Si1-xCx纳米晶粒与SiO2基质之间的界面缺陷。     

Sol–gel synthesis of zircon–effect of addition of lithium ions

The sol–gel method was applied to the preparation of zircon, ZrSiO4 powders. The addition of lithium ions to the ZrO2·SiO2 gels was found to be very effective to produce zircon at temperatures as low as 800–900°C. The zircon formation process in the gels was followed by using X-ray diffraction and i.r. analysis methods. A possible mineralizing mechanism of lithium ions, which is essentially different from the previous ones for the solid-state reaction, was proposed. Namely, the formation of orthosilicate such as Li4SiO4 as an intermediate compound was considered to trigger the zircon formation at low heat-treatment temperatures.     

炭/炭复合材料表面C/SiC/Si-Mo-Cr多层复合防氧化涂层研究(英文)

为提高炭/炭(C/C)复合材料的高温抗氧化性能,采用料浆涂刷法首先在C/C复合材料表面制备了预炭层,然后以Si粉及石墨粉(Si粉与石墨粉的质量配比为:60～80:10～25)为原材料采用包埋法经高温热处理获得C/SiC内涂层,最后在涂有C/SiC内涂层的C/C复合材料表面采用包埋法制备Si-Mo-Cr外涂层。借助扫描电镜、X射线衍射、电子能谱等分析测试手段对涂层试样的微观结构进行了分析,研究了涂层C/C复合材料在1 873 K和1 973 K下的氧化行为。结果表明:由于涂层氧化过程中表面生成了SiO2和Cr2O3复合玻璃层,其在1 873 K温度下表现出优异的防氧化性能,可以有效保护C/C复合材料达135 h。当氧化温度提高至1 973 K并氧化30 h后,该复合涂层氧化过程玻璃层完整性被破坏,涂层失效。     

微波辅助固相法合成锂离子电池正极复合材料Li2FeSiO4/C

以Na2SiO3.9H2O和FeCl2.4H2O为原料,采用低热固相反应获得了分散均匀的β-FeOOH/SiO2前驱体;再以Li2CO3为锂源、聚乙烯醇和超导电炭黑为复合碳源,通过微波辅助固相法合成了Li2FeSiO4/C材料.通过X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和恒电流充放电测试等方法对材料的结构、微观形貌及电化学性能进行表征.650℃下微波处理12 min可获得结晶好、晶粒细小均匀的Li2FeSiO4/C材料;在选用的微波合成体系下,超导碳和聚乙烯醇热分解的无定形碳不仅利于合成反应的顺利进行,而且提高了Li2FeSiO4的整体导电性能.制备的复合正极材料在60℃下0.05C倍率首次放电容量为129.6 mAh/g,0.5C倍率下为107.5 mAh/g,0.5C下15次循环后保持为104.8 mAh/g,具有较好的放电比容量和良好的循环稳定性能.结果表明,微波辅助固相合成工艺是制备Li2FeSiO4/C复合材料的一种很有前景的方法.     

Fabrication of multilayered Ge nanocrystals by magnetron sputtering and annealing

Multilayered Ge nanocrystals embedded in Si and Ge oxide films have been fabricated on Si?substrate by a (SiO(2)+Ge)/(SiO(2)+GeO(2)) superlattice approach, using an rf magnetron sputtering technique with a Ge+SiO(2) composite target and subsequent thermal annealing in N(2) ambient at 750?°C for 5?min. X-ray diffraction (XRD) measurements indicated the formation of Ge nanocrystals with an average size estimated to be 9.8?nm. Raman scattering spectra showed a peak of the Ge-Ge vibrational mode shifted downwards to 298.8?cm(-1), which was caused by quantum confinement of phonons in the Ge nanocrystals. X-ray photoemission spectroscopy (XPS) analysis demonstrated that the Ge chemical state is mainly Ge(0) in the (SiO(2)+Ge) layer and Ge(4+) in the (SiO(2)+GeO(2)) layer in the superlattice structure. Transmission electron microscopy (TEM) revealed that Ge nanocrystals were confined in (SiO(2)+Ge) layers, and had good crystallinity. This superlattice approach significantly improved both the size uniformity of Ge nanocrystals and their uniformity of spacing on the 'Z' growth direction compared with the conventional Ge-ncs fabrication method using a single and thick SiO(2) matrix film.     

Photoelectrochemical and photocatalytic properties of biphasic organic p- and n-type semiconductor nanoparticles fabricated by a reprecipitation process

The visible-light-responsive photoelectrochemical and photocatalytic properties of nanoparticles of C(60), partially hydrolyzed aluminum phthalocyanine chloride (denoted as AlPc), and a composite of the two are reported. The three types of nanoparticles were obtained through a reprecipitation method from N-methyl-2-pyrrolidone solutions of C(60), aluminum phthalocyanine chloride (AlPcCl), and their mixture, respectively. The nanoparticle composite's ultraviolet-visible absorption, diffuse-reflectance and Fourier transform IR spectra, X-ray diffraction pattern, and scanning electron microscopy image are all similar to the sum of those of the C(60) and AlPc particles, respectively. The nano-ordered composite exhibits p/n junctionlike photoelectrochemical characteristics, which were investigated in comparison with those of vapor-deposited C(60) (n-type), AlPcCl (p-type), C(60)/AlPcCl (n/p), and AlPcCl/C(60) (p/n) electrodes. The nanoparticle composite further shows photocatalytic activity for the decomposition of trimethylamine to carbon dioxide in a suspension system.