双效氧电极电催化剂La0.6Ca0.4CoO3的合成及表征

采用有机酸辅助法合成了钙钛矿型La0.6Ca0.4CoO3电催化剂。利用XRD、TEM技术考察了该电催化剂的合成条件,特别是焙烧条件对电催化剂性质的影响并给出优化结果。采用恒流电化学极化方法初步评价了该电催化剂的双效氧电极电催化性能。结果表明,在700 ℃下恒温2 h所制备的电催化剂材料具有单相、单晶的性质,并具有较小的晶粒度,是较佳的合成条件。在该条件下合成的电催化剂具有较好的双效氧电极电催化活性及稳定性,是很有吸引力的可用于MH-空气蓄电池的双效氧电极电催化剂。     

阴极材料Sm0.5Sr0.4Ca0.1CoO3的凝胶浇注法制备及性能

采用凝胶浇注法合成中温固体氧化物燃料电池(IT-SOFC)阴极材料Sm0.5Sr0.4Ca0.1CoO(3SSCC)。利用差热-热重(TG-DTA)、X射线衍射(XRD)、扫描电子显微镜(SEM)、热膨胀、电导率以及交流阻抗谱等技术研究SSCC的结构和性能。结果表明:SSCC与电解质Sm0.2Ce0.8O1.(9SDC)具有良好的化学相容性,电极在1 150℃煅烧4 h后,与SDC电解质可形成良好的接触界面;SSCC的电导率在400~800℃达到400 S/cm以上,50~800℃SSCC阴极的平均热膨胀系数为16.31×10-6 K-1,SSCC的极化电阻较小,700℃时仅为0.13Ω.cm2,预示其可作为IT-SOFC较为理想的阴极备选材料。     

BST/LSCO异质结构的研究

利用脉冲激光沉积法在STO(001)基片上外延生长了La0.5Sr0.5CoO3(LSCO)导电氧化物薄膜,研究了基片温度对LSCO薄膜结构和电性能的影响,并制备了Ni-Cr/BST/LSCO多层膜结构。XRD谱发现,沉积温度在450~700℃均能得到高度(00 l)取向的LSCO薄膜,LSCO(002)峰的半高峰宽FWHM=0.1°~0.2°;在LSCO薄膜上制备的BST介质膜具有良好的c轴取向和较高的表面平整度,其εr约为470,tgδ为0.036~0.060。     

Sulfur solubility in NiO and CoO at 1000°C

The solubility of sulfur in NiO and CoO at 1000°C has been investigated over a wide range of oxygen and sulfur partial pressures using CO, CO₂, and SO₂ as input gases. The concentration of dissolved sulfur increases regularly with sulfur partial pressure but appears to be insensitive to oxygen partial pressure. Dissolution of sulfur did not affect the electrical conductivity of NiO samples. It was concluded that sulfur probably dissolves, in the range 10^–2 –10^–3%, either by exchange with O^–2 ions occuping O^–2 sites as S^–2 ions, or as neutral sulfur on interstitial sites. The scatter in results prevented a more definite conclusion being drawn.     

Application of the Rosenburg kinetic method for determination of the parabolic rate constants for metal oxidation

The Rosenburg continuous kinetic method is proposed for the determination of the parabolic rate constants of metal oxidation as a function of temperature and oxidant pressure. Using this method, it is possible to make numerous measurements in a continuous manner on a single metal sample left in situ in the furnace, thus eliminating systematic errors due to differences between samples. Moreover, using this method it is possible to determine directly from a given kinetic curve such important parameters as the coefficients of chemical diffusion and self-diffusion of the more mobile species in the studied compound and the total equilibrium defect concentration. The latter parameter has been inaccessible up to now by the experimental method. The limits of applicability of this method are given in the paper. As an example of this method, the kinetics of cobalt oxidation are investigated in the range of temperature 1000–1250°C and oxygen pressure 10^–3–1 atm; the results compare favorably with those obtained by other authors. The method is, however, applicable to certain other systems, namely, metal oxides and sulfides.     

借助高分辨电子显微像校正电子衍射强度的动力学效应

针对高分辨电子显微学和电子衍射相结合测定晶体结构的图像处理技术，提出了一种借助高分辨电子显微像来校正低散射角电子衍射强度动力学效应的新方法，将此法试用于Ｂｉ２（Ｓｒ０．９Ｌａ０．１）２ＣｏＯｙ晶体结构分析，结果说明此法有效。     

Unravelling the Elusive Antiferromagnetic Order in Wurtzite and Zinc Blende CoO Polymorph Nanoparticles

Although cubic rock salt‐CoO has been extensively studied, the magnetic properties of the main nanoscale CoO polymorphs (hexagonal wurtzite and cubic zinc blende structures) are rather poorly understood. Here, a detailed magnetic and neutron diffraction study on zinc blende and wurtzite CoO nanoparticles is presented. The zinc blende‐CoO phase is antiferromagnetic with a 3rd type structure in a face‐centered cubic lattice and a Néel temperature of T_N (zinc‐blende) ≈225 K. Wurtzite‐CoO also presents an antiferromagnetic order, T_N (wurtzite) ≈109 K, although much more complex, with a 2nd type order along the c‐axis but an incommensurate order along the y‐axis. Importantly, the overall magnetic properties are overwhelmed by the uncompensated spins, which confer the system a ferromagnetic‐like behavior even at room temperature.     

沉积温度对磁控溅射法制备La_(0.5)Sr_(0.5)CoO_3薄膜微结构和导电性能的影响

采用射频磁控溅射法在(001)SrTiO3基片上制备了La0.5 Sr0.5 CoO3薄膜,研究了沉积温度对La0.5Sr0.5CoO3薄膜微结构和导电性能的影响.结果表明:沉积温度低于400℃时,薄膜以非晶状态存在,未发生外延生长,沉积温度为550℃和650℃时,薄膜在基片上实现了外延生长;随着沉积温度的升高薄膜表面粗糙度呈现规律性的变化;薄膜的电阻率随沉积温度的升高单调下降,650℃沉积薄膜的电阻率最小为1.63μQΩ·cm.     

CoO/CdS纳米复合材料的制备及其光催化降解亚甲基蓝的研究

采用物理气相沉积法制备CoO/CdS纳米复合材料,通过扫描电子显微镜(SEM)、X射线衍射仪(XRD)、X射线能谱仪(E DS)和紫外-可见分光光度计(UV-Vis)对其形貌、结构和光吸收性质进行表征,并以亚甲基蓝溶液的光催化降解为探针反应,在可见光下考察CoO/CdS纳米复合材料的光催化性能.结果表明,CoO/CdS纳米复合材料的光催化活性显著高于CdS纳米颗粒,100 min后亚甲基蓝降解率达到92.4％.     

One-pot synthesis of CoO/C hybrid microspheres as anode materials for lithium-ion batteries

We report a one-pot method to synthesize CoO/C hybrid microspheres via a solvothermal approach. The resulting samples were characterized by thermogravimetric analysis, X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy and charge–discharge test. X-ray diffraction analysis revealed that the as-prepared samples possessed poor crystalline characteristics and were transformed into crystalline materials after thermal treatment. Field-emission scanning electron microscope images showed that the surfaces of these as-prepared spheres were relatively smooth and of about 2.2 μm in diameter. The diameters of the spheres kept unchanged after being annealed at 800 °C in a high purity nitrogen atmosphere under ambient pressure. The preliminary electrochemical test found that the annealed CoO/C hybrid microspheres exhibited an ultrahigh initial discharge capacity of 1481.4 mAh g⁻¹ in the potential range of 3.0–0.01 V. This value was much higher than that of CoO nanoparticles. Although the capacity of the second discharge cycle decayed to 506.2 mAh g⁻¹, the annealed CoO/C hybrid microspheres anode exhibited very stable reversible capacity at about 345 mAh g⁻¹ only after 10 cycles. This rapid stabilization ability was attributed to the matrix effect of carbon, which may effectively prevent the aggregation of small particles during charging–discharging process.