不良导体导热系数测定实验中仪表风扇对实验结果的影响

根据对物体冷却规律的分析,并从实验结果比较,指出稳态法测不良导体导热系数实验中,设置散热盘的冷却过程应与其在稳态过程时的强迫对流散热方式保持一致.     

几种不同形状导体表面的电荷面密度

对无限大导体表面，楔形导体表面，半圆柱形凸起表面电荷面密度进行了具体的计算，结果表明在静电平衡的条件下导体表面虽曲率相同，但表面电荷面密度却可以不同．     

BaSnF4 fast ion conductor: Variations versus the method of preparation and anomalous temperature variation of the quadrupole splitting

A new method of preparation of high performance fluoride ion conductor, BaSnF₄, by water leaching of newly discovered barium tin(II) chloride fluorides, has been designed, and the materials have been studied and compared to the solid prepared by the usual dry method. The unit-cell parameters and crystallite dimensions were found to vary with the method of preparation. In addition, the crystallite dimensions were found to be highly anisotropic for the samples obtained by the wet method. The Mössbauer spectrum is made of a large tin(II) quadrupole doublet, and a broad tin(IV) oxide peak due to surface oxidation. The tin(II) spectrum is in agreement with covalently bonded tin(II) having a strongly stereoactive lone pair. An unusually high dependence of the quadrupole splitting at low temperatures was observed (5.8 times larger than for α-SnF₂).     

导体壳内外的电场彼此独立的简易证明

本文提供了一种证明导体壳的内外电场彼此独立的简易方法.     

用化学溶液方法在Ni-5at%W基底上制备La2Zr2O7过渡层的研究

La2Zr2O7(LZO)过渡层以其独特的物理化学性质越来越受到人们的关注。本文以乙酰丙酮镧和乙酰丙酮锆为前驱盐,丙酸为溶剂配置前驱液,用化学溶液方法(CSD)在具有立方织构的Ni-5at%W基底上制备了LZO过渡层薄膜。研究了前驱液成分、性质以及退火温度对LZO成相以及取向的影响。用常规XRD和X射线四环衍射仪分析了LZO薄膜的相成分和织构。结果显示,在1050℃下退火可以获得强立方织构的LZO薄膜,其中(222)峰的Phi扫描半高宽值为8.95°;(400)峰的Chi扫描半高宽值为6.8°。用高分辨扫描电子显微镜(FE-SEM)观察到LZO薄膜表面均匀致密,没有裂纹和空洞。     

High-temperature transport properties, thermal expansion and cathodic performance of Ni-substituted LaSr2Mn2O7−δ

The substitution of manganese with nickel in LaSr₂Mn₂O_7−δ, where the solubility limit corresponds to approximately 25% Mn sites, enhances the Ruddlesden-Popper phase stability at elevated temperatures and atmospheric oxygen pressure. The total conductivity of LaSr₂Mn_2−yNi_yO_7−δ (y=0-0.4) decreases with nickel additions, whilst the average thermal expansion coefficients calculated from dilatometric data in the temperature range 300-1370 K increase from (11.4-13.7)×10⁻⁶ K⁻¹ at y=0 up to (12.5-14.4)×10⁻⁶ K⁻¹ at y=0.4. The conductivity and Seebeck coefficient of LaSr₂Mn_1.6Ni_0.4O_7−δ, analyzed in the oxygen partial pressure range 10⁻¹⁵-0.3 atm at 600-1270 K, display that the electronic transport is n-type and occurs via a small polaron mechanism. Reductive decomposition is observed at the oxygen pressures close to Ni/NiO boundary, namely ∼2.3×10⁻¹¹ atm at 1223 K. Within the phase stability domain, the electronic transport properties are essentially p(O₂)-independent. The steady-state oxygen permeability of dense LaSr₂Mn_1.6Ni_0.4O_7−δ membranes is higher than that of (La,Sr)MnO_3−δ, but lower if compared to perovskite-like (Sr,Ce)MnO_3−δ. Porous LaSr₂Mn_1.6Ni_0.4O_7−δ cathodes in contact with apatite-type La₁₀Si₅AlO_26.5 solid electrolyte exhibit, however, a relatively poor electrochemical performance, partly associated with strong cation interdiffusion between the materials.     

Neutron powder diffraction as a characterization tool of solid oxide fuel cell materials

Neutron diffraction is a powerful tool for the characterization of materials and, particularly, oxides. Oxide materials find applications in solid oxide fuel cells (SOFCs) as solid electrolytes as well as anode and cathode materials. As a structural probe, neutrons are specially suitable for the crystallographic study of oxides, given the comparable scattering factors of O and other heavier elements, allowing its precise localization in the crystal structure. Many problems can be addressed by neutrons, related to the octahedral tilting in perovskites, phase transitions, order–disorder phenomena, presence of anionic vacancies, etc. Neutrons make possible an accurate determination of the thermal factors and provide a visualization of the diffusion paths in ionic conductors. Neutrons allow the localization of light atoms such as hydrogen, and make possible the distinction between neighbouring elements, typically Fe and Mn. In this work we will describe some recent applications of this technique in the field of solid electrolytes and electrode materials, including some examples from our group.     

镜像系统和镜像天线

对电荷电流体系在理想导体平面所形成的镜像系统的各物理量作了全面分析，并得出镜像天线的结果。     

Development of cube textured Ni–5 at.%W alloy substrates for coated conductor application using a melting process

Biaxially textured Ni–5 at.%W substrates have been prepared by cold rolling, followed by three different annealing routes. In this paper, the processes of melting Ni and W metals, flat rolling, various annealing methods are described in detail. The Ni–5 at.%W tapes annealed under either high vacuum or flowing Ar (7% H₂) gas were characterized by X-ray pole figures, ODF, EBSD as well as AFM analysis. The texture analysis indicated that as fabricated tapes have a sharp cube texture formed after annealing at a wide temperature range of 800–1100 °C. The high quality of cube orientation on tapes was obtained after a two-step annealing (TSA), where the percentage of the cube texture component was as high as 93.5% within a misorientation angle smaller than 8° from EBSD analysis. Furthermore, it was also observed that the number of twin boundaries in this tape decreased with respect to that of tapes annealed both in vacuum and one-step gas annealing. From AFM on 1 μm² areas, it was concluded that the roughness (RMS) on the tape surface reached 0.98 nm.     

Photo-electrochemical properties of multi-layered thin films composed of chalcogenide and superionic conductor glasses

Multi-layered thin films, which consisted of metallic silver, GeSe₃ glass, and silver oxyhalide superionic conductor glass were prepared. Photo- and electrochemical reaction of metallic silver with the chalcogenide glass layer was studied by optical absorbance and cyclic-voltammetry. Photo-doping of silver through the superionic glass layer was observed using evaporated AgI---Ag₂MoO₄ film and it was partly undoped by electrochemical treatment. However, no photo-doping was observed for the cell consisting of a AgI---AgPO₃ dip-coated layer. The doped silver was dissolved into the GeSe₃ layer during the photo-doping process. However, it formed another intermediate compound layer (probably silver selenide) during the electrodoping process.