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Detecting Intermediate Particles in the Growth of Colloidal Zinc Oxid Nanoparticles in Different Chemical Routes Using MCR-ALS

Kafrashi, Fatemeh | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42055 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Jalali Heravi, Mahdi; Hormozinezhad, Mohammad Reza
  7. Abstract:
  8. Zinc oxide(ZnO) nanoparticles have been used in a wide-ranging of applications such as transparent UV protection, medical treatments, light emitting diodes, sensors and photovoltaic cells. Many applications of ZnO nanoparticles could be improved by changing the particle size, shape and morphology. In order to take advantage of the unique size dependent properties observed for ZnO anoparticles, knowledge of how particle growth can be controlled is required. As an alternative to transmittance electron microscopy (TEM), which is already used in the study of size and monodispersity of ZnO nanoparticles during synthesis, we proposed a simple spectrophotometric method coupled with chemometric methods for analyzing overlapped and complex spectral data, that has been easily obtained from solution growth. The evolutionary Uv-visible absorbance data of ZnO quantum dots through particle formation via precipitation methods in different conditions were analyzed using factor analysis, evolving factor analysis, and multivariate curve resolution-alternative least-squares analysis. By using these techniques three or four chemical factors (depending on chemical routs), attributed to the ZnO nanoparticles of different sizes, were detected and the oncentration profiles and pure spectra of the particles were resolved. The interpretation of the evolution profiles of the detected ZnO nanoparticles were achieved by Ostwald ripening mechanism. The formation of magic size nanoclusters was detected at the beginning of the reaction, which was followed by the formation of larger particles. At the end of the reaction, a thermodynamically stable ZnO nanoparticle was detected
  9. Keywords:
  10. Growth Mechanism ; Zinc Oxide Nanoparticles ; Multivariate Curve Resolution-Alternative Least Square (MCR-ALS)

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