Pair distribution function (PDF) analysis of mesoporous α-Fe2O3 and Cr2O3

Abstract

We have measured atomic pair distribution functions of novel mesoporous metal oxides, α-Fe₂O₃ and Cr₂O₃. These have an ordered pore mosaic as well as crystalline structure within the pore walls, making them an interesting class of materials to characterise. Comparison of “bulk” and mesoporous data sets has allowed an estimate of long range structural coherence to be derived; ≈125 Å and ≈290 Å for α-Fe₂O₃ and Cr₂O₃ respectively. Further “box-car” analysis has shown that above ≈40 Å both mesoporous samples deviate greatly from their bulk counterparts. This is attributed to the pores of the mesoporous structure creating voids in the pair-correlations, disrupting long range order.