films. Aluminium single crystals of crystallographic orientations (100),
(110) and (111) were used for the investigation and they concluded
that the substrate orientation affected the anodic filmand optical reflectance
with the (111) plane giving the lowest reflectance, and also that
different variations were observed under different anodizing conditions.
Similarly, Saetre and co-workers [33] further strengthened the
theory that the optical properties of the anodic film formed on aluminiumdepend
on the crystallographic orientation of the grains. Takahashi
and Murakami [34] found that grain orientation affected the shape of
oxide film and striationswere observed along a certain crystallographic
direction. This finding is equally reported by many other researchers,
who have also revealed that distinct crystallographic orientations produce
different regularities in the arrangement of nanopores that are formed on
aluminium substrates (e.g. the reports by Beck and co-workers [27,28]
that showed that aluminium crystals with (100) orientation produce the
best ordering).