We studied sol-gel processing of thick and crack-free TiO 2 films to synthesize structural color materials. The viscosity of the alkoxide-based precursor sols was stabilized by the addition of acetyl acetone, which improved control of the spin coating thickness. We used a TiO 2 /SiO 2 /TiO 2 triple-layer structure and second-order reflection conditions to produce structural coloration. This design yielded a sharp spectral peak and bright coloration; however, a TiO 2 layer with a thickness greater than 200 nm was required, which is much thicker than that required for the first-order of reflection. Crack formation in the thick films was suppressed by the addition of ethyl cellulose to the precursor sols. As a consequence, color-tuned TiO 2 /SiO 2 /TiO 2 films were successfully prepared and exhibited various bright colors in the visible light wavelength range, including two primary colors of light, namely blue and green. Green coloration from flake-shaped particles was also demonstrated.
We report the effect of a Cr layer on the glass substrate during the growth of carbon nanotubes (CNTs) by chemical vapor deposition. When Fe was used as a catalyst in the CNT growth, longer CNTs were obtained by increasing the thickness of the Cr layer. However, CNTs were not grown on the surface with a thick Cr film and Co or Ni catalyst. These results arise from a difference in the mechanism of CNT formation when using different catalyst metals.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.