Structure and thermal stability of nanocrystalline materials

Nanocrystalline materials, which are expected to play a key role in the next generation of human civilization, are assembled with nanometre-sized “building blocks” consisting of the crystalline and large volume fractions of intercrystalline components. In order to predict the unique properties of nanocrystalline materials, which are a combination of the properties of the crystalline and intercrystalline regions, it is essential to understand precisely how the structures of crystalline and intercrystalline regions vary with decrease in crystallite size. In addition, study of the thermal stability of nanocrystalline materials against significant grain growth is both scientific and technological interest. A sharp increase in grain size (to micron levels) during consolidation of nanocrystalline powders to obtain fully dense materials may consequently result in the loss of some unique properties of nanocrystalline materials. Therefore, extensive interest has been generated in exploring the size effects on the structure of crystalline and intercrystalline region of nanocrystalline materials, and the thermal stability of nanocrystalline materials against significant grain growth. The present article is aimed at understanding the structure and stability of nanocrystalline materials.     

Computerized comprehensive numerical data system on the thermophysical and other properties of materials established at CINDAS/Purdue University

A computerized materials properties numerical data system has been developed and established at the Center for Information and Numerical Data Analysis and Synthesis (CINDAS) of Purdue University, which is a comprehensive, one-line, interactive, menu-driven, user-friendly, expert data system. This data system contains both critically evaluated reliable reference data and experimental data on the thermophysical, mechanical, electrical, optical, and other properties of various types of materials. It permits both the search of data and information for specified materials and properties and the search for materials that meet a set of requirements specified by the user (i.e., computer-aided materials selection). It permits also the on-line functional manipulation, statistical analysis, and mthemtical study of the retrieved data. The development, operation, functions, scope, contents, and other features of the data system are presented and discussed.Paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A.     

溶剂对FTO薄膜的结构和光电性能的影响

采用喷雾热解法(SPD),分别使用甲醇、乙醇、异丙醇、正丁醇和去离子水作为溶剂制备F掺杂的SnO₂(FTO)透明导电薄膜,使用X射线衍射仪、扫描电子显微镜、四点探针电阻仪、霍尔效应仪和紫外可见分光光度计等手段对薄膜进行测试和表征,研究了溶剂对FTO薄膜结构、形貌和光电性能的影响,研究了溶剂对FTO薄膜结构与光电性能的影响。结果表明：FTO薄膜具有四方相金红石结构;使用不同溶剂制备的薄膜,其表面形貌和颗粒尺寸明显不同;使用甲醇为溶剂制备的FTO薄膜呈现饱满的金字塔状,晶粒尺寸均匀,结构致密,具有最佳的综合光学和电学性能,其电阻率可达4.43×10^-4 Ω·cm,载流子浓度为9.922×10²⁰ cm^-3,品质因数为1.646×10^-2 Ω^-1,可见光区透射比均大于75%。     

Structure and mechanical properties of reaction-sintered ceramic composite materials based on titanium and hafnium diborides

The structure and mechanical characteristics of ceramic composite materials based on titanium and hafnium diborides produced by reaction sintering in the course of hot pressing have been studied. It has been shown that ultradispersed structure is responsible for high mechanical characteristics of the synthesized composites.     

Present research on thermal radiation properties and characteristics of materials

This paper reviews the recent advances in our spectroscopic research on radiation properties and characteristics of solid and liquid materials, from thermal engineering point of view. The topics discussed are optical constants of metallic materials, radiation characteristics of the real surfaces in actual industrial environments, those of semi-transparent scattering-absorbing media, and those of human body and environmental surfaces of human living space. The review also includes the algorithm for radiation pyrometry and the demand for radiation data of new materials and for new engineering techniques. It is concluded that the development of engineering models is important for the systematic research of the complicated radiation phenomena and that generation and compilation of pertinent data are necessary.Paper presented at the Second U.S.-Japan Joint Seminar on Thermophysical Properties, June 23, 1988, Gaithersburg, Maryland, U.S.A.