Iridium oxide films produced by reactive sputtering (SIROFs) have
considerably higher densities than those made by other techniques such as
the anodic reaction at metal surfaces which contain pores and Microvoids. It
has been previously reported that SIROFs deposited with substrate
temperatures of 300K are amorphous. Here we report x-ray and electron
diffraction measurements on SIROFs deposited on Al2O3,
Si, NaCI and MgO substrates at 40°C. The x-ray diffraction patterns, I(Q),
show “diffuse” structure that extends to beyond Q(=4εsinθ/)
=10Â−1. We show that it is possible to reproduce qualitatively
the main features of the diffraction pattern by convolving the crystalline
rutile powder pattern with a Lorentzian profile. The width of this profile
is compatible with that determined from the Scherrer equation although
significant peak shifts and texture are observed. This analysis reveals that
as-deposited SIROFs are crystalline with particle sizes in the range 25À to
35Å rather than amorphous (for which no crystalline model would be
appropriate). The electron microdiffraction data are also consistent with a
crystallite size of a few nm and high resolution TEM reveals lattice fringes
from crystallites few nm in size. The peak shifts, however, remain to be
explained.