Optimal filling fraction of Ta2O5 inverse opals

•Ta2O5 inverse opals were prepared by infiltration of colloidal crystal templates.•We combine self-assembly process and sol–gel chemistry-based opal infiltration.•The infiltration was investigated to achieve inverse opals with optimal filling fraction.•The results correlate the concentration of the precursor with the filling fraction.•The inverse opals were studied by SEM, EDS and XRD.

Tantalum pentoxide (Ta2O5) inverse opals were prepared by combining the self-assembly process and sol–gel chemistry-based opal infiltration. The inverse opal was made by the infiltration of a tantalum(V) ethoxide solution in the interstices of the polystyrene colloidal crystal template, and then removing the original opal template by calcination. The infiltration process as well as the optimal precursor concentration has been investigated in order to obtain Ta2O5 inverse opals with the optimal filling fraction. The effects of processing, template sphere size, morphology, structural properties, filling fraction and composition of the inverse opal are provided by scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy analysis (EDS) and powder X-ray diffraction (XRD). The results correlate the concentration of the precursor with the filling fraction of the template.