Surface Structure and Chemistry of the Boron-Rich Solids

9421037金属硼化物是非常耐人寻味的材料，具有极高的硬度、化学惰性和非常高的熔点。这些固体中有许多具有独特的性质，使它们在各种应用中都很有用。例如，在各种电子光学器件中，硼化镧和硼化铈被广泛用作电子发射阴极，在这方面远远优于钨和其他难熔金属。用于1-2keV同步辐射单色器的高质量的硼化钇单晶正在开发中。由于表面结构和表面性质在热电子发射中的重要性，稀土六硼化物一直是许多基础表面科学研究的对象。然而，许多最重要的性质还没有被研究。在使用六硼化物作为阴极时，最重要的问题之一是它们与所有真空室中存在的背景气体的相互作用。在这项工作中，反射吸收红外光谱将被用来表征简单的背景气体在硼化镧和硼化铈表面的吸附和分解。扫描隧道显微镜还将用于对具有重要技术意义的金属硼化物表面数量的结构研究。对富硼固体的表面化学知之甚少。这些固体构成了种类繁多的材料。它们作为电子束光刻的阴极和各种电子器件中的电子发射阴极引起了电子工业的高度兴趣。此外，过渡金属二硼化物作为金属表面的薄膜也是需要超硬涂层的重要应用领域。***

9421037 Trenary The metal borides are intriguing materials that are extremely hard, chemically inert, and have very high melting points. Many of these solids have unique properties making them useful in various applications. For example, lanthanum boride and cerium boride are widely used as electrmn emitting cathodes in a variety of electron optical devices and are far superior to tungsten and other refractory metals for this purpose. High-quality single crystals of yttrium boride are being developed for use as monochromators of 1-2 keV synchrotron radiation. Because of the importance of surface structure and surface properties in thermionic emission, the rare-earth hexaborides have been the subject of many fundamental surface science studies. Yet many of the most important properties have not been investigated. One of the most important questions in the use of hexaborides as cathodes concerns their interaction with the background gases present in all vacuum chambers. In this work, reflection absorption infrared spectroscopy will be used to characterize the adsorption and decomposition of simple background gases on the lanthanum boride and cerium boride surfaces. Scanning tunneling microscopy also will be used for structural studies of the number of technologically important metal boride surfaces. %%% Little is known about the surface chemistry of boron-rich solids. These solids constitute a wide and varied class of materials. They are of high interest to the electronics industry as cathodes for electron beam lithography, and electron emitting cathode in a variety of electron devices. Furthermore, transition metal diborides as thin films in metal surfaces are important application areas requiring ultra-hard coatings. ***