Lee et al , Applied Physics A (in press).

1. Ion Beam Synthesis of Highly Crystalline and Nanostructured Thin FilmsJung-Kun Lee, University of Pittsburgh, DMR 0847319 A sol-gel technique is one of the more powerful methods to synthesize nanostructured films with novel electronic, photonic, and biological properties. We present an investigation on the fully epitaxial growth of sol-gel films by using ion-irradiation enhanced synthesis. A structural analysis indicates that ion irradiation can dramatically influence the epitaxial growth of sol-gel grown anatase TiO2 films by reducing the crystallization and epitaxial growth temperature. The nuclear energy deposition at the amorphous-crystalline interface plays a dominant role in the epitaxial growth of the films. In addition, electronic collisions during ion irradiation enhance chemical decomposition of residual organics. This, in turn, balances the crystallization rate and the organic component escape rate inside the films, leading to the low temperature growth of high quality sol-gel films. FTIR spectra of sol-gel grown TiO2 films exposed to the ion irradiation, which indicates the decomposition of polymer networks (insets: the electron micrographs of sol-gel TiO2 film showing the effect of the ion-beam on low temperature densification, a) thermally annealing at 900 oC with a ramping rate of 5oC/min, b) ion beam processing at 350 oC). Lee et al, Applied Physics A (in press).

2. Study on the Rheological Properties of Nanoparticle-Dispersed SolsJung-Kun Lee, University of Pittsburgh, DMR 0847319 The interdisciplinary nature of this project has enabled the PI to attract the interests of undergraduates in different engineering and science programs and offer them research experiences on the renewable energy. Currently, the undergraduate student, Travis Sefzik with the major of mechanical engineering, is performing the research to understand the dispersion behavior of the nanoparticles in partially hydrolized sols. Through a series of rheological tests, undergraduate Travis and his co-workers concluded that the size and surface potential of the nanoparticles are two important parameters to uniformly mix the nanoparticles within the sols. This information will be used to align chemically synthesized metal nanoparticles in ZnO sols and to coat metal embedded ZnO films on substrates A junior student, Travis Sefzik, measures the viscosity of the sols containing nanoparticles by using a rheometer. He is performing undergraduate research in PI’s laboratory.