The Effects of Processing on the Morphology of Nanoparticles
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M11.10.1
The Effects of Processing on the Morphology of Nanoparticles Christopher R. Perrey, Julia M. Deneen, and C. Barry Carter* Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN * corresponding author: [email protected] Abstract One of the major challenges confronting the utilization of nanoparticles in industrial and social applications is that of producing the nanoscale materials. Of the methods of manufacturing nanoscale materials, processes involving plasmas have been shown to be cost-effective and versatile in the production of chemically diverse material. Using transmission electron microscopy, individual nanoparticles produced by a thermal plasma-based production method have been examined. The observations of these studies imply that the thermal history of the nanoparticles during formation is of great importance in the determination of the resulting nanoparticle morphology. Such results have the potential to enable the manufacturing of nanoparticles of a specific size and shape from plasmas. Background Recent research has shown that when the dimensions of materials are reduced to less than approximately 100 nm, the properties observed often deviate from those observed from bulk materials. One such example is the hardness of Si nanoparticles which have been found to be much greater than that of bulk Si [1-3]. The potential for applications utilizing such modified properties are seemingly limitless with the promise to revolutionize many aspects of industry and society [4]. Unfortunately, the promise of nanoscale materials is limited by the current lack of a method to consistently manufacture quantities of material with a specified chemical and morphological composition for a low cost. Of the many candidate nanoparticle production methods, plasmabased processes offer many advantages including chemical versatility, flexible operating conditions, and compatibility with numerous substrates. However, plasma processes are complex and not well understood, often producing materials with a high degree of agglomeration or chemical impurities [5-7]. Since the properties of nanoscale materials depend intimately on their structure [1-3], a better understanding of the relationship between the production and resulting structure is necessary. Although theoretical approaches can lead to insights about formation processes, experimental observations of the product material are necessary to test theoretical assumptions. The inherently small size of the particles produced makes the use of transmission electron microscopy (TEM) a necessity. The TEM can yield chemical and structural information at the atomic level while providing data about other items of interest, such as the size distribution and morphology of the nanoparticles [8].
M11.10.2
Experimental Nanoparticles were created using hypersonic plasma particle deposition (HPPD). In HPPD, vapor-phase reactants are injected into an Ar-H2 thermal plasma which is expanded to low pressure through a nozzle, driving homogenous nuc
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