Author/Authors :
Y. KOBAYASHI?، نويسنده , , ‡، نويسنده , , T. ISHIZAKA§، نويسنده , , Y. Kurokawa، نويسنده ,
Abstract :
This review describes our study on preparation of alumina films by a sol-gel process and
their several applications that have been investigated since 1986. Alumina films were
prepared from alkoxide or inorganic salt. Both as-prepared alumina films were transparent
in ultraviolet, visible and near infrared regions. The alumina from inorganic salt (inorganic
alumina) was structureless even after annealed at 300–700◦C in air, while the alumina from
alkoxide (alkoxide alumina) was in pseudo-boehmite at an annealing temperature lower
than 400◦C and was in γ- or δ-type at 400–700◦C. Both alumina films became opaque after
annealed at temperatures above 1000◦C. The inorganic alumina film annealed at 800◦C
showed a gas permeability that was influenced by physico-chemical properties of
penetrant and alumina. Composite films of alumina and poly(vinyl alcohol) (PVA) were
hydrophilic but insoluble in water, and removal of PVA from the composite films by
annealing at 600◦C led to formation of transparent alumina films. Such properties enabled
us to use a counter diffusion method for fabricating γ-Fe2O3-doped alumina films. Alumina
films doped with organic dyes such as laser dyes, hole-burning dyes and non-linear optical
dyes, which were fabricated by gelation of dye-added alumina sol, exhibited laser
emission, hole-spectra and second- or third-harmonic generation properties, respectively.
Hydrogenation of alkene was catalyzed by Ni nanoparticles doped alumina films that were
prepared by gelation of Ni2+ solution-added alumina sol and annealing the Ni2+-doped
alumina gel in hydrogen gas. Nonlinear optical properties were observed for alumina films
doped with CdS, Au and Ag nanoparticles, which were fabricated by gelation of Cd2+,
HAuCl4 and AgNO3 solution-added alumina sols and annealing the Cd2+-doped alumina gel
in H2S gas and the Ag+- and Au3+-doped alumina gels in H2 gas. Rare earth metal
ion-doped alumina films, which were prepared by gelation of rare earth metal ion
solution-added alumina sol and annealed the ion-doped alumina gel, exhibited not only
normal luminescence but also up-conversion emission, energy transfer type luminescence
and long lasting luminescence. C 2005 Springer Science + Business Media, Inc.