中温平板型固体氧化物燃料电池研究

采用流延法制备Ni/YSZ阳极支撑体 YSZ电解质复合膜素坯.经等静压,共烧结而得到的复合膜,其YSZ电解质层的厚度在1530μm之间,面积大于100cm2.再将由柠檬酸盐法合成的Ce0.8Sm0.2O1.9(CSO)和固相法合成的La0.6Sr0.4CoO3(LSCO)相继沉积到YSZ膜上形成有CSO中间层的复合阴极,从而构成Ni/YSZ/CSO/LSCO的中温平板型固体氧化物燃料(单体)电池,其中Ni/YSZ为阳极,CSO是中间层,LSCO为阴极.以H2作燃料气,O2为氧化气,850℃下,该单电池开路电压达1.1V,最大输出功率密度0.2W/cm2.本文还对该单电池复数阻抗谱进行了分析讨论.     

Gadolinia-doped ceria films deposited by RF reactive magnetron sputtering

Gadolinia-doped ceria (GDC) films were prepared by RF reactive magnetron sputtering from a Gd-10 at.% Ce alloy target in reactive O₂/Ar gas mixtures and annealed at 700 °C for 2 h. Material characteristics and chemical compositions of GDC films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Electrical behaviors were measured by AC impedance in the range of 500–700 °C at OCV for air condition. The microstructure of GDC films was found to be an assembly of columnar crystallites with a cubic fluorite structure. The total conductivity of 700 °C-annealed GDC (GDC-1) with the obtained composition of (Ce_0.911Gd_0.089)O_1.938 was higher than that of bulk yttria-stabilized zirconia (YSZ), but smaller than bulk GDC. The governing mechanism of conduction of sputtered-GDC electrolyte films was mainly governed by a grain boundary process, which resulted in a blocking effect and the lower conductivity of thin films than that of bulk GDC samples. Our results suggested that sputtered-GDC films with a comparable conductivity can be used as solid electrolyte layers for a solid oxide fuel cell (SOFC) system as compared to the well-known YSZ.     

Electrical conductivities and microstructures of LSM,LSM-YSZ and LSM-YSZ/LSM cathodes fabricated on YSZ electrolyte hollow fibres by dip-coating

Lanthanum strontium manganite – La_0.80Sr_0.20MnO₃ (LSM), LSM-Yttria stabilised zirconia (LSM-YSZ) composite and LSM-YSZ/LSM double-layer cathodes were separately fabricated on Yttria stabilised zirconia (YSZ) electrolyte hollow fibres by dip coating; their electrical conductivities and microstructures were then determined by the direct current four-probe method and scanning electron microscopy (SEM), respectively. Excellent cathode-electrolyte and cathode-cathode adhesion without delamination were achieved by the dip-coating fabrication method. The apparent electrical conductivities of porous LSM, LSM-YSZ and LSM-YSZ/LSM cathodes manufactured on YSZ hollow fibre by dip-coating and sintered at various temperatures in the range 1273–1473 K for 3 h, were 1.8 × 10³–5.5 × 10³ S/m, 0.32–209 S/m and 1.3 × 10³–5.5 × 10³ S/m, respectively, at measurement temperatures of 673–1073 K. The operating temperature dependence of the apparent electrical conductivity of the LSM, LSM-YSZ and LSM-YSZ/LSM cathodes was defined by the Arrhenius equation for electrical conductivity. The activation energies for electrical conductivity were derived as 0.106–0.147 eV, 0.83–0.94 eV, and 0.104–0.146 eV for the LSM, LSM-YSZ and LSM-YSZ/LSM cathodes, respectively. The LSM-YSZ and LSM-YSZ/LSM cathodes were strongly influenced by the YSZ and LSM phases, respectively.     

在多晶金属基片上制备双轴织构YSZ膜

采用调制偏压射频磁控溅射技术在多晶ＨａｓｔｅｌｏｙＣ金属基带上制备钇稳定的ＺｒＯ２薄膜（ＹＳＺ），得到了ｃ轴织构和部分平面内双轴织构的ＹＳＺ薄膜。用Ｘ射线衍射θ２θ扫描、ω扫描和扫描对ＹＳＺ薄膜的织构进行了测量，并研究了沉积条件对织构形成的影响。     

Local atomic structure of a zirconia-based americium transmutation fuel

(Zr,Y,Am)O₂ with 6 and 19 mol% Am were prepared by infiltration of americium in porous yttria-stabilised zirconia (YSZ) beads. Samples were sintered at 1600 °C in Ar/H₂ to yield Am(III). By annealing them at 1000 °C in flowing air, the Am is oxidised to Am(IV). Both Am(III) and Am(IV) samples exhibit the presence of a single (Zr,Y,Am)O₂ phase with fluorite structure. The local atomic structure around the Zr, Y, and Am atoms is determined by EXAFS analysis. The Zr-O bond distance decreases from 2.15 to 2.12 Å with increasing Am(III) content, whereas the Y-O bond distance is independent of Am content and oxidation state. The Am(III)-O bond distance is 2.37 Å for both Am concentrations, while oxidation to Am(IV) decreases the Am(IV)-O distance to 2.28 Å, with a simultaneous expansion of the environment around the Zr atoms. The Am-O bond distances are contracted compared with the compounds Am₂Zr₂O₇ and AmO₂ and the distances expected from the ionic radii.     

Characterization of plasma fluorinated zirconia for dental applications by X-ray photoelectron spectroscopy

This paper discusses fluorination of biomedical-grade yttria-stabilized zirconia (YSZ) by sulfur hexafluoride plasma treatment and characterization of near-surface chemistry products by X-ray photoelectron spectroscopy (XPS). Deconvolution of the Zr 3d and Y 3d XPS core level spectra revealed formation of both ZrF₄ and YF₃. In addition, seven-coordinate ZrO₂F₅ and/or ZrO₃F₄ phases were deconvolved, retaining similar atomic coordination as the parent oxide and believed to have formed by substitutional displacement of oxygen by fluorine. No additional components attributed to yttria oxyfluoride were deconvolved. Argon ion sputter depth profiling determined the overlayer to be ∼4.0 nm in thickness, and angle resolved XPS showed no angle dependence on component percentages likely due to fluorination extending into the grain boundaries of the polycrystalline substrates. Importantly, the conversion layer did not induce any apparent change in zirconia crystallinity by inspection of Zr-O 3d_5/2,3/2 peak positions and full-width-at-half-maximum values, important for retaining its desirable mechanical properties.     

Reactivity of lithium and barium carbonates with ZrO2:Y2O3 and Nasicon in solid state electrochemical gas sensors

The mutual reactivity in mixtures containing Nasicon (Na₃Zr₂Si₂PO₁₂) or YSZ (ZrO₂:Y₂O₃) solid electrolytes with Li₂CO₃ or Li₂CO₃:BaCO₃ sensing electrode materials was investigated using simultaneous DTA and TG and ex situ XRD techniques. The uncontrolled chemical reaction is suspected to be responsible for the instability of electrochemical gas sensors constructed from these materials. DTA and TG results obtained for Nasicon-carbonate mixtures indicate the possibility of reaction in the temperature range from about 470 to 650°C, which overlaps the sensor operating temperature range (300–525°C). The results obtained for YSZ-carbonate mixtures indicate that reaction between carbonate and the ZrO₂ takes place at higher temperatures and cannot explain the instability drift of investigated sensors. The mechanism of observed reactions in systems studied is also discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Preparation of YSZ Coated AISI-Type 316L Stainless Steel by the Sol-Gel Coating Method and Its Corrosion Behavior in Molten Carbonate

The effect of heat-treatment conditions on the corrosion behavior of yttria stabilized zirconia (YSZ) coated AISI-type 316L stainless steels in molten carbonate are investigated. YSZ films on stainless steel were prepared by the sol-gel method. While the sample heat-treated at 800°C for 2 hours in air has an uneven surface microstructure with macrocracks, a YSZ coated sample heat-treated in argon has an even microstructure. The polarization resistance and corrosion rate of YSZ coated sample heat-treated in air were deteriorated from 6.948 cm² and 364.7 mpy (millimeter per year) to 3.291 cm² and 769.8 mpy, respectively, by the corrosion for 100 hours due to its poor surface microstructures. At the same experimental condition, meanwhile, those corrosion parameters of YSZ coated sample heat-treated in argon were 15.43 cm² and 164.2 mpy, respectively, and those were improved to 18.83 cm² and 134.6 mpy after the corrosion for 100 hours. This is attributed to the YSZ film with well developed surface microstructures. The concentration profiles of elements and X-ray diffractograms indicate that the oxide layer of YSZ coated sample heat-treated in argon had a triple layer structure composed of outer YSZ film, in between Fe₂O₃ layer, and inner chromium rich layer during corrosion.     

Preparation of Y-Ba-Cu-O film on metal substrate with buffer layers deposited by ion beam assisted deposition

Ion beam assisted pulsed laser deposition of biaxially aligned yttria-stabilized zirconia (YSZ) was used to produce a buffer layer for YBCO film on polycrystalline metallic substrate. The YSZ layers were biaxially aligned with (001) axis normal to the substrate. The minimum FWHM of (111) phi-scan of the YSZ was 19°, and the minimum FWHM of the rocking curve of YSZ was 4.5°. Highly c-axis oriented biaxially aligned YBCO thin films were epitaxially grown by laser ablation on these layers, with J_C(77K, 0T) = 2.1 × 10⁵ A/cm², . Project supported by the National Center for R&D on Superconductivity of China.