| Descript |
252 p |
| Note |
Source: Dissertation Abstracts International, Volume: 66-08, Section: B, page: 4217 |
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Major Professor: Kenneth J. Klabunde |
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Thesis (Ph.D.)--Kansas State University, 2005 |
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Nanoscale materials are one of the largest fields of research in Chemistry and Materials Science. Within the area of nanoscience, semiconductor nanoparticles, or quantum dots, are of great interest to Physicists, Chemists, Engineers, and Biologists. Much of the focus on these materials to date is in gaining an understanding of the theory and physical properties of these materials that bridge the gap between quantum and solid state chemistry. Due to the many current applications of semiconductors and the promise of nanoscale materials, many investigations into novel applications are being undertaken. To realize these applications, new methods for the synthesis of nanoscale semiconductors must be developed. Foremost, methods must be developed to synthesize sizable quantities of material if practical applications are ever to be gained |
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This thesis presents the solvated metal atom dispersion method (SMAD) as a highly effective route to produce gram scale quantities of nanoscale semiconductors. The SMAD method consists of evaporation of bulk materials and co-condensation with solvent molecules at liquid nitrogen temperatures. ZnS, ZnSe, CdS, CdSe, CdTe, PbS, and SnS have been successfully prepared as high surface area nanocrystalline powders with free surfaces. Crystallite size and surface area are reliably controlled by reaction conditions |
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Further modification of the SMAD method provides a synthetic procedure for preparation of large quantities of monodisperse, stabilized cadmium sulfide and cadmium selenide mixture. After the initial formation of the nanoparticles, they are stabilized by capping agents, such as thiols as phosphine oxides, which enable their improved dispersion in solvents. Similar to what has been developed for gold particles, a refluxing of the sample, referred to as digestive ripening, is carried out with the semiconductor-thiol-toluene colloid. The effect is a narrowing of particle size distribution and almost monodisperse colloids are obtained. These colloids exhibit strong fluorescence and are stable over very long periods of time. These monodisperse colloidal solutions have a tendency to organize in two- and three-dimensional structures |
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Finally, metal oxides impregnated with semiconductor nanoparticles were synthesized demonstrating the versatility of SMAD method. These hybrid materials exhibit different visible absorption and emission than the pure materials |
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School code: 0100 |
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DDC |
| Host Item |
Dissertation Abstracts International 66-08B
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| Subject |
Chemistry, Inorganic
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Chemistry, Physical
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Engineering, Materials Science
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0488
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0494
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0794
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| Alt Author |
Kansas State University
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