Characteristics and Optical Properties of Ni Nanograins Reduced on TiO2 Film

概要

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NiO/TiO2 films with various NiO film thicknesses ranging from 10 to 320 nm were deposited on silicon and glass substrates by e-beam evaporation at 200 °C, and then annealed in H2 atmosphere at 500 °C for 1 h in order to reduce the NiO film to Ni grains on the TiO2 film. The structures of titanium oxide, NiO, and Ni/TiO2 were determined by X-ray diffraction (XRD) analysis, and the morphology of the Ni/TiO2 films was observed by scanning probe microscopy. The ultraviolet–visible (UV–vis) transmittance and vis absorption of the Ni/TiO2 films were measured by UV–vis spectrophotometry. The results showed that an amorphous titanium oxide was obtained as deposited at 200 °C and that the structure change to the anatase phase after 500 °C annealing. As deposited, crystalline NiO films with XRD patterns similar to that of powder were obtained; however, diffraction peaks of (111) and (200) Ni appeared after annealing in H2 atmosphere. Ni nanograins, coarsened grains, and films were obtained on the TiO2 films when the NiO film with a thickness from 10 to 320 nm was reduced in H2 atmosphere at 500 °C. The transmittance of the Ni/TiO2 films decreased with an increase in Ni particle size. The vis absorption measurement showed that the peak shifted toward a shorter wavelength with a decrease in Ni particle size.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2008-01-25