Ion storage properties of CeO2 and mixed CeO2/SnO2 coatings

Ion storage CeO₂ and CeO₂/SnO₂ coatings were prepared by the sol-gel dip-coating method using an aqueous-based process. The influence of added SnO₂ in the CeO₂ oxide coatings on the inserted/extracted charge was determined by chronocoulometric measurements. It was found that for 60 nm thick film, the inserted/extracted charge was twice (Q=10 mC cm^–2) as large for films containing 17 mol% SnO₂, if compared to pure CeO₂. The effect of the addition of SnO₂ to the mixed oxide coatings on their optical properties and structural characteristics was studied.     

晶态骨架介孔CeO2和CeO2-ZrO2的合成与结构表征

以乙酸铈、乙酸锆为无机源,嵌段共聚物P123为模版剂,采用溶胶-凝胶法合成了介孔CeO2及CeO2-ZrO2复合体,用XRD、氮气吸附脱附、TEM、HRTEM、SAED等对材料进行了表征.结果表明,所得介孔CeO2具有规则的晶态孔道结构,孔径约在10nm左右,特别是其孔壁晶粒高度定向排列且平行于孔道方向.原位高温TEM观测表明,该介孔CeO2在800℃仍具有很高的孔道完整性.掺杂ZrO2后发现,在ZrO2摩尔含量低于30%时仍具备高度定向排列结构,高于30%时骨架晶粒取向逐渐趋向无序化.     

Synthesis of CeO2 and Y2O3-Doped CeO2 Composite Fibers by Electrospinning

Electrospinning was employed to produce homogeneous inorganic-organic composite fibers from alcohol solutions containing polyvinyl butyral (PVB) and precursor of yttrium and cerium ions. Upon heat treatment, ceria and yttria-doped ceria fibers were obtained. The fibers retained the original morphology observed in the as-spun composition. X-ray diffraction was used to identify the crystalline phases of the final products. Scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and BET analysis were employed to study the ceramic-phase formation and the morphological evolution of the fibers. Thus, uniform ceria and yttria-doped ceria fibers several micrometers long of high-phase purity were produced. The CeO₂ and the CeO₂ with Y₂O₃ fibers presented average diameters that ranged from 0.8 to 1.7 µm, and the distribution of specific surface ranged from 24 to 127 m²/g after heat treatment at 1000°C.     

Single crystalline CeO2 nanotubes

Here,we report a facile synthetic methodology to prepare uniform single crystalline CeO₂ nanotubes through a hydrothermal transformation of CeO₂ nanorods in aqueous Ce(NO3)3 solution.A chemically driven etching-dissolution-deposition mechanism is proposed,involving the surface Ce³⁺hydrolysis and dissolution at tips of nanorods and subsequent redeposition and crystallization on the outer sides of nanorods.Compared to CeO₂ nanorods,CeO₂ nanotubes exhibited the richer structural defects,higher reducibility and larger surface area,leading to a higher haloperoxidase-like activity.     

Preparation of nanostructured CeO2 coated TiO2

Abstract

The synthesis of nanostructured TiO₂ and nanostructured CeO₂ coated TiO₂ has been investigated. On the basis of the synthesis of nano-TiO₂, nano-CeO₂ coated TiO₂ was prepared by use of sol- gel technology. X-ray diffraction, TEM, and high resolution electron microscopy were employed to analyse the characteristics and microstructures of the synthesised materials. The TEM analysis indicated that nano-CeO₂ coated TiO₂ is formed of agglomerated particles with an average size of 70 nm with the TiO₂ located at the centre surrounded by nanostructured CeO₂ polycrystals. Owing to the catalytic effect of nano-CeO₂, the oxygen sensitivity of nano-CeO₂ coated TiO₂ was better than that of pure nano-TiO₂.     

Preparation and Characterization of CeO2/YSZ/CeO2 Buffer Layers for YBCO Coated Conductors

CeO2 seed layer was deposited on rolling-assisted biaxially textured metal substrates by direct-current （DC） magnetron reactive sputtering. The effect of deposition temperature on epitaxial orientation of CeO2 thin films was examined. High quality CeO2 layers were achieved at deposition temperature from 750℃ to 850℃.Subsequently yttria-stabilized zirconia （YSZ） and CeO2 films were deposited to complete the buffer layer structure via the same process. The best samples exhibited a highly biaxial texture, as indicated by FWHM （full width half maximum） values in the range of 4°-5°, and 2°-4° for in-plane and out-of-plane orientations,respectively. Secondary ion mass spectrometer analysis confirmed the effective prevention of buffer layer against Ni and W metal interdiffusion. Atomic force microscope observations revealed a smooth, dense and crack-free surface morphology, which provided themselves as the good buffer structure to the YBa2Cu3O7-δ（YBCO） coated conductors.     

CeO1.5-stabilized tetragonal ZrO2

Ceria-stabilized tetragonal zirconia polycrystals show high toughness and high resistance to the low-temperature ageing degradation. However, ceria is less effective in stabilizing tetragonal zirconia compared to yttria and other trivalent oxides. The tetravalent oxide of CeO₂ can be easily reduced to the trivalent CeO_1.5, but phase separations occur leading to the destabilization of the tetragonal phase or the stabilization of the cubic phase. A procedure of high-temperature sintering and low-temperature reduction has been developed for preparing CeO_1.5-stabilized tetragonal zirconia. It was found that 9 mol% CeO_1.5 could stabilize the tetragonal zirconia to room temperature and that the stability region in the CeO_1.5-ZrO₂ system was extended to the lower dopant content region. The CeO_1.5-stabilized tetragonal zirconia had a lower tetragonality and lower transformability compared to the CeO₂-stabilized tetragonal zirconia with the same dopant mole percentage. The changes in the phase composition, tetragonality and stability caused by the reduction of CeO₂ to CeO_1.5 have been discussed in relation to the changes of oxygen stoichiometry, which is considered of the firstorder importance in the stabilization of polymorphous zirconia.     

Effect of CeO2 on reaction-sintered mullite-ZrO2 ceramics

The effect of ceria on mullite formation and the sintering of zircon and alumina powders was investigated. Quantitative X-ray powder analysis was used to determine the formation of mullite and zirconia of both monoclinic and tetragonal forms. Scanning electron microscopy and electron-probe microanalysis were used for microstructural analysis. It was found that the addition of CeO₂ enhanced the formation of mullite and increased the fraction of tetragonal zirconia. The addition of CeO₂ caused the formation of mullite directly from reaction of zircon with alumina without decomposition of zircon into zirconia and silica. In addition to forming a liquid phase, the ceria essentially formed a solid solution with zirconia. The fracture toughness of the mullite-zirconia composites was about 5.5–6.0 MPa m^1/2.     

纳米CeO2的制备及其应用

对近年来国内外涌现的各种制备纳米CeO2的方法和关键技术进行了详述,其中包括：固相法、沉淀法、溶胶-凝胶法、水热法、微乳液法、电化学法、喷雾法、气相法。介绍了纳米CeO2的主要应用领域和研究前沿。     

纳米CeO2在聚合物中的应用

综述了纳米CeO2在提高聚合物的抗老化性能、力学性能、热稳定性能、导电性能及纳米CeO2/聚合物复合材料作为催化材料方面的应用。     

超微氧化铈粉体的表面改性及分散性能研究

为提高纳米氧化铈粉体在高聚物中的分散性能,以廉价的硬脂酸和实验室自制的分散液,对超微氧化铈粉体进行表面改性.FT-IR及DTA实验表明超微氧化铈粉体表面包裹了一层表面改性剂分子;TEM及SEM照片均表明改性后的超微氧化铈粉体在低表面能的高聚物中具有良好的分散性.