title: Thermal stability of Cu and Cu2O nanoparticles in a polyimide film.
abstract: Nanoparticles of Cu or Cu oxide dispersed in a polyimide (PI) film were fabricated by reaction of polyamic acid with a thin Cu film during imidization. In this paper, the thermal stability of the Cu or Cu oxide nanoparticles was investigated under various atmospheres. The PI/nanoparticle composites were heat-treated at 140 degrees C and 250 degrees C in air, N2, Ar, and 5% H2 atmospheres. Nanoparticles in the PI film were characterized by UV-VIS spectroscopy and transmission electron microscopy. The optical absorption peaks originating from Cu or Cu2O nanoparticles were changed by heat-treatment in different atmospheres. When Cu nanoparticles were oxidized by heat-treatment in air, the surface plasmon resonance (SPR) peak originating from the Cu nanoparticles disappeared. The quantum confined absorption peak of Cu2O was not affected by heat-treatment in N2 or Ar. Cu2O nanoparticles were reduced by heat-treatment at 250 degrees C in 5% H2 atmosphere and a new SPR peak appeared. Our results show that Cu nanoparticles are easily oxidized and highly dense Cu nanoparticles can be formed by reducing Cu2O nanoparticles.
authors.affiliation: Division of Materials Science and Engineering, Hanyang University, Seoul 133-791, Korea.
authors.forename: Jae-Youn
authors.initials: JY
authors.lastname: Choi
authors.forename: Wenguo
authors.initials: W
authors.lastname: Dong
authors.forename: Dong Joo
authors.initials: DJ
authors.lastname: Choi
authors.forename: Chong S
authors.initials: CS
authors.lastname: Yoon
authors.forename: Young-Ho
authors.initials: YH
authors.lastname: Kim