合成甲醇铜系催化剂硫中毒机理与该催化剂上CO、H_2吸附机理的研究

合成甲醇铜系催化剂是广泛用于工业反应的高活性催化剂。但对含硫气体十分敏感，易硫中毒。本论文通过常压、220 ℃反应温度下硫中毒对催化活性、反应物吸附性质、催化剂表面组成与体相结构、孔分布的影响探讨了铜系催化剂硫中毒机理。同时通过考察CO、H_2在米中毒铜系催化剂上咐附、脱附、程脱及竞争吸附的性质，探讨了CO、H_2吸附机理。得到以下结果。常压下，铜系催化剂遇含硫气体引起不可逆中毒。当硫浓度较低时，H_2S占据了铜活性中心，使CO不能在该吸附中心吸附，造成失活。由于H_2S吸附引起催化剂表面铜晶相冲长也是失活的直接原因。中毒时，硫并非均匀吸附，而主要是吸附在50～80A孔内。H_2S浓度较高时，硫与催化剂反应形成硫化物是失活的主要原因。H_2在铜系催化剂上的吸附当吸附温度为225 ℃时可分为两部分，可逆吸附与不可逆吸附。可逆吸附中心属铜吸附中心，不可逆吸附中心是H_2与部分吸附的CO共同的竞争的咐附中心。CO在该温度下的可逆吸附发生在催化剂铜活性表面上。

钙钛石型复合氧化物La_xSr_(1-x)M_yM'_(1-y)O_3(M, M' = Mn, Fe, Co)的固体物理化学性质和催化性能的研究

钙钛石型复合氧化物由于具有许多独特的物理化学性质，如多种类型的磁性和导电性、对多种物理和化学因素的敏感性、高温下的稳定性和结构的明确易调性等长期以来一直受到固体物理、固体化学和催化科技工作者重视，本文第一部分详细总结了文献中有关这类氧化物的结构、电子状态、电磁性质、表面吸附性能、稳定性以及反应机理和催化性能等方面的重要结果。第二部分为催化剂的制备和表征方法。第三部分针对文献中研究较少的B位取代钙钛石型氧化物，系统研究了系列化合物LaM_yM'_(1-y)O_a (M, M' = Mn, Fe, Co)的固体物理化学性质和对NH3和CO氧化反应的催化性能，讨论了它们之间的关系。1. 催化剂的制备、晶体结构与光谱性质。2. LaM_yM'_(1-y)O_3(M、M' = Mn、Fe、Co)r的氧化还原性质和稳定性。3. 过渡金属离子的状态及其之间的相互作用。4. 催化剂中氧的形态。5. 氨氧化性能与固体物化性质之间的关系。6. 一氧化碳氧化与固体物化性质之间的关系。

Co(salen)作为辅酶B_(12)模型物及化学修饰电极的电化学研究

本论文从合成Co(salen)开始，对Co(salen)在电化学现场合成辅酶B_(12)模型物的工作进行了尝试。进一步地，用Co(salen)制作了两种化学修饰电极，并对它们的性质进行了较为详细的考察。同时还将这两种修饰电极应用于电催化研究工作，得到了较为满意的结果。

Room-Temperature Ferromagnetism in Co-Doped In2O3 Nanocrystals

Co-doped In2O3 nanocrystals showing room-temperature ferromagnetism have been successfully prepared by a simple sol-gel synthesis route. The sample displays it clear ferromagnetism behavior above 300 K. Phase and structure analyses reveal that the nanocrystals are crystallized with Co ions substituted for In ions in the In2O3 matrix, and no trace of secondary phases or clusters is detected. The experimental results are explained theoretically by first-principles calculations based on density functional theory, which indicate that the native ferromagnetic behavior of Co-doped In2O3 could be mainly ascribed to the strong d-d coupling of the magnetic ions.

INTERFACIAL REACTIONS IN THE CO/SI/GAAS AND SI/CO/GAAS SYSTEMS

The interfacial reactions between thin films of cobalt and silicon and (100)-oriented GaAs substrates in two configurations, Co/Si/GaAs and Si/Co/GaAs, were studied using a variety of techniques including Auger electron spectroscopy, x-ray diffraction, and transmission electron microscopy. The annealing conditions were 200, 300, 400, 600-degrees-C for 30 min, and rapid thermal annealing for 15 s. It was found that Si layer in the Co/Si/GaAs system acts as a barrier at the interface between Co and GaAs when annealed up to 600-degrees-C. The interfacial reaction between Co and Si is faster than that between Co and GaAs in the system of Si/Co/GaAs. The sequence of compound formation for the two metallizations studied (Co/Si/GaAs and Si/Co/GaAs) depends strongly on the sample configuration as well as the layer thickness of Si and Co (Co/Si atomic ratio). From our results, it is promising to utilize Co/Si/GaAs multilayer film structure to make a CoSi2/GaAs contact, and this CoSi2 may offer an alternative to the commonly used W silicides as improved gate metallurgies in self-aligned metal-semiconductor field effect transistor (MESFET) technologies.

INTERACTION OF CO WITH SI AND SIO2 DURING RAPID THERMAL ANNEALING

The interaction of Co with Si and SiO2 during rapid thermal annealing has been investigated. Phase sequence, layer morphology, and reaction kinetics were studied by sheet resistance, x-ray diffraction, Auger electron spectroscopy, x-ray photoelectron spectroscopy, and scanning electron microscopy. With increasing annealing temperature, Co film on Si(100) is transformed sequentially into Co2Si, CoSi, and finally CoSi2 which corresponds to the minimum of sheet resistance. No evidence of silicide formation was observed for Co/SiO2 annealed even at the high temperature of 1050-degrees-C.

图形衬底上硅区双离子束选择淀积Co研究

报道了利用质量分离低能双离子束淀积法在硅-氧化硅图形衬底上采用不同的工艺条件淀积钴(Co)离子，并生长硅化钴薄膜。扫描俄歇微探针(SAM)和X光电子能谱(XPS)测量结果表明，只在纯硅区探测到了硅化钴；而氧化硅区始终未见有钴的迹象。很好地实现了在图形衬底上钴离子的选择淀积和硅化钴薄膜的选择生长。