Metal Colloids and Thin Films

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This award supports the participation of Dr. Kenneth J. Klabunde of Kansas State University in a program of cooperative research with Dr. Galo Cardenas-Trivino of the University of Concepcion, Chile, focusing on the producion and characterization of a new class of stable colloids in thin-film form. The U.S. principal investigator has developed a method, based on the clustering of metal atoms in organic solvents at low temperature, for producing stable thin-film metal colloids using non-aqueous media. The resulting colloidal particles are unusually pure and can be combined in thin-film forms with interesting electrical and optical properties. The properties of the resulting colloids and metallic films are not predictable a priori, but may turn out to be insulating, metallic, or semiconducting, and therefore may have important uses. For example, the films may optically resemble metal films but be only poor electrical conductors. These properties, and the possibilities that others may be evidenced, form the stimulus for this work, which extends previous colloidal formation using Au and Pd to Pt, Cu, Ag, Zn, Cd, Ga, In, Ge, Sn, and Pb. Various solvents will also be used in colloidal formation. The resultant colloid particles and thin films will be studied using electrophoresis, electron microscopy, spectroscopy, thermogravimetric analysis and other electrical and thermal measurements. The objectives of the collaboration include the characterization of both the colloidal particles and the thin films produced from them. In this cooperative project colloid and thin film preparation will be carried out primarily in the U.S. investigator's laboratory, while characterization will primarily be pursued in the laboratory of the Chilean collaborator. Considering the range of properties of the materials already observed, in addition to an improvement in our general understanding of particle stabilization in non-aqueous media, this work could result in the development of materials useful in the ceramics, electronics, or catalyst industries, with applications as decorative coatings, semiconductors, conductors, solar cells, etc.