SANS analysis of opal structures made by the capillary deposition method

Small angle neutron scattering (SANS) is used to analyze the structure of opals and inverse opals made by the capillary deposition method. We show that there is no deformation in special lattice directions such as the growth direction and the support plane direction. However, effects of twinning of the dense-packed structure and plane-like lattice perturbations have been observed. The latter appear as linear surface disturbances. We propose a model with an anisotropic distribution of stacking faults which delivers the different peak intensities in the neutron diffraction pattern. The rocking curves show that small perfect crystal parts are aligned better than ±3° and ±11° for the opals and inverse opals, respectively.