注浆法制备YSZ固体电解质及其性能研究

以多孔石膏模具为成型载体，以8mol%钇稳定氧化锆(YSZ)粉体为原料，采用注浆法制备出具一定体积和形状的全稳定YSZ固体电解质。对注浆成型工艺中制备素坯的各个环节的主要影响因素(粘结剂种类及用量的选择、固相含量、球磨时间等)与浆料稳定性、流动性及素坯密度之间进行优化实验，确定了制备悬浮稳定、流动性好的浆料的实验参数。 将利用上述浆料于多孔石膏模中成型后的素坯进行等静压操作，进一步提高其致密度，为制备致密化高的电解质材料奠定了条件。结果表明：注浆成型后的素坯在进一步等静压处理后相对密度可达53%左右，可以说注浆成型法是一种成型具一定体积素坯的简单可行的方法。 继而将成型后的素坯于不同的烧结条件下进行常压烧结，并对烧结后YSZ固体电解质的致密化程度、微观形貌(SEM)及导电性能进行测量和表征，借助于交流阻抗谱测量其导电性，采用氧浓差电池法测定其离子迁移数(能斯特响应)。通过对烧结体的性能分析，建立其致密程度、导电性与烧结条件之间的关系，并以此为依据来优化烧结工艺。 结果表明：样品的致密度随烧结温度和烧结时间的增加而提高，电导率随着致密度的提高而不断增加，其中在1550℃烧结3h的电解质制品500℃时的阻抗测试结果表明其离子导电率已超过投入实际使用的最小限定值；结合样品的微观形貌分析，在较高的烧结温度下晶粒增长显著，平均粒径可以达到微米级，而低温下增长不显著。 立足于砖层模型和多晶电解质晶界空间电荷层导电特性，对不同粒径的YSZ多晶固体电解质材料的晶界电导进行分析，结果表明随平均粒径的减小，YSZ多晶固体电解质材料晶界空间电荷层电势减小，而其中氧空位浓度增加，因此可以说，对高纯物质而言，晶粒的减小有助于提高其整体电导性。因而就优化烧结工艺而言，要制备高性能YSZ固体电解质可以以达到高致密度、抑制晶粒显著生长为原则来进行探讨。

Fast analysis of capillary electrochromatography with non-porous ODS as the stationary phase

High-speed capillary electrochromatography was developed on both short and long packed columns with 2 mu m non-porous ODS as the stationary phase. Factors that affect the analysis time of samples, such as voltage, electrolyte concentration, pH and organic modifier concentration in the mobile phase, were studied systematically. Fast analysis of aromatic compounds within 13 seconds was realized with column efficiency of 573,000 plates/m and a R.S.D.% of the retention times of all components in 8 consecutive injections below 1.0%. which demonstrated the high efficiency and high reproducibility of such a technique. In addition, DNPH derived aldehydes and ketones in both standards and environmental samples were separated with high speed.

Determination of total iron binding capacity of serum by capillary electrophoresis

A capillary electrophoresis (CE) technique for determining total iron binding capacity (TIBC) of serum has been developed. The optimum serum pretreatment involves the following major steps: at first, saturate serum transferrin with Fe+3; then, dissociate them completely after removing excess unbound Fe. Finally, complex the released iron with phenanthroline, a chromophore, to make suitable for the CE analysis. Ammonium acetate (pH = 5.0) was used as CE background electrolyte solution. In this system, a good linear correlation coefficient was maintained over the range 0.5 similar to 10 mu M (r = 0.9979, n =12). Seven adult serum samples were studied and the TIBC parameters measured. In the present system, 10 similar to 30 mu L serum is sufficient for determination. The study shows that the CE technique described is a powerful method for rapid, efficient, sensitive and reliable analysis and hence particularly suitable for clinical application.

Capillary electrochromatography with monolithic poly(styrene-co-divinylbenzene-co-methacrylic acid) as the stationary phase

A new kind of monolithic capillary electrochromatography column with poly(styrene-co-divinylbenzene-co-methacrylic acid) as the stationary phase has been developed. The stationary phase was found to be porous by scanning electron microscopy and the composition of the continuous bed was proved by IR spectroscopy to be the ternary polymer of styrene, divinylbenzene, and methacrylic acid. The effects of operating parameters, such as voltage, electrolyte, and organic modifier concentration in the mobile phase on electroosmotic flow were studied systematically, The retention mechanism of neutral solutes on such a column proved to be similar to that of reversed-phase high performance liquid chromatography. In addition, fast analyses of phenols, chlorobenzenes, anilines, isomeric compounds of phenylenediamine and alkylbenzenes within 4.5 min were achieved.

On-line concentration of proteins in pressurized capillary electrochromatography coupled with electrospray ionization-mass spectrometry

Pressurized capillary electrochromatography (pCEC) and electrospray ionization-mass spectrometry (ESI-MS) have been hyphenated for protein analysis. Taken cytochrome c, lysozyme, and insulin as samples, the limits of detection (LODs) for absolute concentrations are 10(-11) mol (signal-to-noise ratio S/N = 3) with relative standard deviations (RSDs) of retention time and peak area, respectively, of less than 1.7% and 4.8%. In order to improve the detection sensitivity, on-line concentration by field-enhanced sample-stacking effect and chromatographic zone-sharpening effect has been developed, and parameters affecting separation and detection, such as pH and electrolyte concentration in the mobile phase, separation voltage, as well as enrichment voltage and time, have been studied systematically. Under the optimized conditions, the LODs of the three proteins could be decreased up to 100-fold. In addition, the feasibility of such techniques has been further demonstrated by the analysis of modified insulins at a concentration of 20 mu g/mL.

Investigation of LSM1.1-ScSZ composite cathodes for anode-supported solid oxide fuel cells

La0.8Sr0.2Mn1.1O3 (LSM1.1)-10 mol% Sc2O3-Stabilized ZrO2 co-doped with CeO2 (ScSZ) composite cathodes were investigated for anode-supported solid oxide fuel cells (SOFCs) with thin 8 mol% Y2O3-stabilized ZrO2 (YSZ) electrolyte. X-ray diffraction (XRD) results indicated that the ScSZ electrolytes displayed good chemical compatibility with the nonstoichiometric LSM1.1 against co-firing at 1300 degrees C. Increasing the CeO2 content in the ScSZ electrolytes dramatically suppressed the electrode polarization resistance, which may be related to the improved surface oxygen exchange or the enlarged active area of cathode. The 5Ce10ScZr was the best electrolyte for the composite cathodes, which caused a small ohmic resistance decrease and the reduced polarization resistance and brought about the highest cell performance. The cell performances at lower temperatures seemed to rely on the electrode polarization resistance more seriously, than the ohmic resistance. Compared with the cell impedance at higher temperatures, the higher the 5Ce10ScZr proportion in the composite cathodes, the smaller the increment of the charge transfer resistance at lower temperatures. The anode-supported SOFC with the LSM1.1-5Ce10ScZr (60:40) composite cathode achieved the maximum power densities of 0.82 W/cm(2) at 650 degrees C and 2.24 W/cm(2) at 800 degrees C, respectively. (c) 2005 Elsevier B.V. All rights reserved.