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991.
针对C原子的扩散过程,研究了Al-石墨在机械合金化过程中的结构变化.用X射线衍射仪(XRD)、扫描电子显微镜、拉曼光谱仪及计算机模拟观察,分析了不同球磨时间的Al-C混合物的结构.结果表明,球磨初期,石墨晶粒尺寸的减小及六角石墨转变为Turbostratic 结构,使石墨的X射线衍射峰迅速减弱,以至消失.随球磨时间的增加,C原子逐渐扩散到Al的点阵中形成固溶体. 将Al-C固溶体进行退火处理,便转变为Al4C3.即使在球磨产物的XRD图中观察不到石墨的衍射峰后,继续球磨数十小时,拉曼光谱表明球磨样品中仍有未与Al反应的单质石墨. 相似文献
992.
E. Gómez E. Guaus J. Torrent X. Alcobe E. Vallés 《Journal of Applied Electrochemistry》2001,31(3):349-354
The electrodeposition of tin + cobalt alloys from a slightly acidic sulfate–gluconate bath on both vitreous carbon and copper substrates has been studied for different [Sn(II)]/[Co(II)] ratios in the bath, varying between 1/10 and 1/2. A relationship between the electrochemical stripping analysis and the morphology of the deposits has been found. Two different types of deposit were obtained. At low [Sn(II)]/[Co(II)] ratios and relatively high deposition rates a nodular, cobalt-rich, nanocrystalline coating was obtained, while at high [Sn(II)]/[Co(II)] ratios and low deposition rates a new, well-defined tetragonal SnCo phase was obtained, with cell parameters of a = 3.087 Å and c = 5.849 Å. This structure favours hydrogen evolution. 相似文献
993.
利用油气生成的地质历史过程中温度-时间补偿效应,运用“慢速升温+长时间恒温”的方法,采用热重分析法和改进的封闭系统热解装置,在热解终温范围350℃~550℃,升温速率5K/min,恒温时间24h等比较温和的反应条件下,研究了不同变质程度的神木煤、东山煤和阳城煤的热解过程,并运用傅立叶变换红外光谱(FTIR)、X-射线衍射(XRD)、元素分析等现代仪器分析技术研究了不同温度下热解所得到的系列化固态产物.研究结果表明:采用改进的热解装里能得到较好的模拟热解实验结果,至少在上述实验条件下可以得到很好的结果;煤样的元素组成、物理和化学特性、所含官能团种类和数量等不同,使得在相同条件下所发生反应不同,尤其是高变质程度的阳城无烟煤与其它煤差异更大.所以,固态产物的组成特性和随热解温度的变化规律不同;相对高阶煤而言,选用中等变质程度的烟煤可以得到更好的模拟效果. 相似文献
994.
Implication of the microstructure of binary Cu/ZnO catalysts for their catalytic activity in methanol synthesis 总被引:2,自引:0,他引:2
M.M. Günter T. Ressler B. Bems C. Büscher T. Genger O. Hinrichsen M. Muhler R. Schlögl 《Catalysis Letters》2001,71(1-2):37-44
Binary Cu/ZnO catalysts with varying molar ratios (90/10 through 10/90) were studied under methanol synthesis conditions at 493 K and at atmospheric pressure. The methanol synthesis activity of the catalysts was correlated to their specific Cu surface area (N2O reactive frontal chromatography, N2O RFC) after reduction in 2 vol% H2 at 513 K. Activity data were supplemented with a detailed analysis of the microstructure, i.e., crystallite size and strain of the reduced Cu and the ZnO phases after reduction using X-ray diffraction line profile analysis. The estimated copper surface area based on a spherical shape of the copper crystallites is in good agreement with data determined by N2O RFC. A positive correlation of the turnover frequency for methanol production with the observed microstrain of copper in the Cu/ZnO system was found. The results indicate a mutual structural interaction of both components (copper and zinc oxide) in the sense that strained copper particles are stabilized by the unstrained state of the zinc oxide microcrystallites. The observed structural deformation of ZnO in samples with higher Cu loading can originate, for instance, from epitaxial bonding of the oxide lattice to the copper metal, insufficient reduction or residual carbonate due to incomplete thermal decomposition during reduction. Additional EXAFS measurements at the Cu K and the Zn K edge show that about 5% ZnO are dissolved in the CuO matrix of the calcined precursors. Furthermore, it is shown that the microstructural changes (e.g., size and strain) of copper can be traced back to the phase composition of the corresponding hydroxycarbonate precursors. 相似文献
995.
Al和Ti对Mg2Ni结构中部分Mg的取代,得到与Mg2Ni晶体结构不同的新型合金.多晶X射线结构分析表明,其化学式为Mg3MNi2(M=Ti,Al),立方晶系,空间群Fd3m, Z=16,48个Mg坐落在48(f),16个 M(M=Al, Ti)坐落在16(d)位,32个Ni坐落在32(e)位,Mg3AlNi2的晶胞参数a=1.15474(2)nm, Mg3TiNi2的a=1.16178(2)nm.与Mg2Ni相比,Mg3MNi2合金的晶体密度更大,Mg-Ni键长更长,吸放氢温度降低,循环寿命延长. 相似文献
996.
997.
矿渣MTC水化机理实验研究 总被引:2,自引:0,他引:2
针对钻井行业中采用矿渣MTC进行油气井固井的特点,利用XRD对矿渣MTC水化过程产物以及膨润土等进行了物相鉴定实验研究,根据硅酸盐化学理论、无机材料化学理论,分析了矿渣MTC的水化机理.研究结果表明:矿渣由大量玻璃体和少量水泥熟料晶体组成,膨润土中含有大量的钠蒙脱石和石英,使其与玻璃体的性能相似,可以在强碱作用下被激活.硅酸三钙、硅酸二钙、硅钙石等都可以水化生成硅酸钙凝胶和Ca(OH)2,随着钙硅比的减小,它们的活性减弱,并且生成的硅酸钙凝胶也具有不同的钙硅比.反应过程的水化产物Ca(OH)2可以作为矿渣的激活剂,与SiO2作用生成低钙硅比的C-S-H凝胶,其中水泥熟料物质的水化进程与其在24h之内的水化特性相吻合. 相似文献
998.
999.
The hydrogenation and dehydrogenation behaviours of the YNi3.5Al0.5Mg compound were studied by in situ X-ray diffraction under hydrogen pressure and at room temperature. The changes of (i) the lattice parameters, (ii) the crystallite size and (iii) the lattice strain during the sorption process (i.e. along the PC isotherms) were studied. These results indicate that the crystallite size decreases by a factor of 2. The micro deformations increase at first and then tend to almost zero at the end of the sorption cycle. This behaviour is explained in terms of co-existence of the metal (i.e. α phase) and metal hydride (i.e. β phase) phases. The change in crystallinity is consistent with the hydrogen induced amorphisation process existing in a lot of AB2 compounds. No anisotropic effects can be highlighted on this pseudo-AB2 compounds in contrary with what could be observed in AB5 compounds. 相似文献
1000.
B. Muthuraaman Vinod Mathew S. Austin Suthanthiraraj 《Solar Energy Materials & Solar Cells》2008,92(12):1712-1717
A new dye-sensitized solar cell containing a detergent-based solid-state composite electrolyte has been investigated. The electrolyte is composed of Triton-X (C16H26O2)n, with a powder mixture of surface-treated carbon powder, a fast ion-conducting material (FCM) 40(Cu1−xAgxI)−30(Ag2O)−30(WO3), (x=0.2), I−/I3− redox couple and an iodine complexing agent. The introduction of this detergent-based solid-state composite electrolyte forms a mosaic-like surface for the smooth transfer of photo-ejected electrons between electrodes. The current-voltage characteristics of TiO2 nanocrystalline dye-sensitized solar cells based on the above solid-state composite electrolyte measured under simulated sunlight with AM 1.5 at 40 mW/cm2 have revealed a short circuit current of 0.7 mA, open circuit voltage of 588 mV and fill-factor of 0.4, thus yielding an over-all conversion efficiency of 0.4%. These results have suggested the origin of appreciably, high charge transfer and the suppressed reverse reaction of electrons as due to the presence of the detergent dispersed with suspensions of electron- and ion-conducting phases. 相似文献