REG: X-Ray Powder Diffractometer for Characterization of Ultrafine Materials and Novel Structures

CTS-9411901将购买一台x射线粉末衍射仪，用于支持麻省理工学院化学工程和化学系的几个研究项目。这些项目包括通过纳米晶体合成、溶胶-凝胶处理和层状结构柱化产生的超细材料的结构剪裁。这些项目的共同主题在于纳米级结构的设计，纳米级结构由纳米级晶体或二维层状结构、高体积分数的表面和界面以及微孔网络组成。x射线衍射法将用于晶相的鉴定，以及晶体尺寸、晶格应变、薄膜厚度、层间间距和热稳定性的表征。新型纳米结构的主要应用有：(1)高效脱除SO2的催化剂，(2)部分氧化和加氢脱硫的微孔分子混合多组分催化剂，(3)低温可烧结的高强度si3n4基结构复合材料，以及(4)用于氢净化和膜反应的高过电选择性致密金属膜。前三个项目目前由美国国家科学基金会资助。该衍射仪还将用于新型氮化物和氧离子导体的相鉴别和结构测定。利用固相氧化物前驱体氨解法制备了具有有趣的金属和磁性能的三元氮化物。这些多晶粉末的精确结构表征将用x射线里特费尔德细化进行。对具有固有氧空位的新型层状铋氧化物也提出了类似的结构测定方法。它们作为低温超离子氧离子导体具有很大的潜力，在燃料电池和空气分离技术中具有重要的应用价值。本研究由美国化学学会石油研究基金资助。＊＊＊

ABSTRACT Jackie Y. Ying CTS-9411901 A X-ray powder diffractometer will be purchased and dedicated to support several research projects in the Departments of Chemical Engineering and Chemistry at Massachusetts Institute of Technology. The projects include structural tailoring of ultrafine materials generated through nanocrystalline synthesis, sol-gel processing, and pillaring of layered structures. The common theme of these programs lies in the design of nanoscale structure, which consists of nanometer-sized crystallites or two-dimensional layered structures, high volume fraction of surfaces and interfaces, and microporous network. X-ray diffractometry will be used in the identification of crystalline phases, and in the characterization of crystallite size, lattice strain, film thickness, interlayer spacing, and thermal stability. Novel nanostructures are targeted towards the following applications: (1) high activity catalysts for SO2 removal, (2) microporous molecularly mixed multicomponent catalysts for partial oxidation and hydrodesulfirization, (3) low-temperature sinterable, high strength Si3N4-based structural composites, ad (4) high permselectivity dense metallic membranes for hydrogen purification and membrane reaction. The first three projects are currently funded by NSF. The proposed diffractometer will be also used in the phase identification and structural determination of new nitrides and oxygen ion conductors. Ternary nitrides which have interesting metallic and magnetic properties will be synthesized via ammonolysis of solid state oxide precursors. Accurate structural characterization of these polycrystalline powders will be performed with X-ray Rietveld refinement. Similar structural determination is also proposed for novel layered bismuth oxides with intrinsic oxygen vacancies. They have great potential as low-temperature superionic oxygen ion conductors, which will be very useful in fuel cell and air separation technologies. Research is funded through gran ts from Division and American Chemical Society Petroleum Research Fund. ***