TiO2, CeO2, and standard aluminum dioxide (Al2O3) were obtained from Sigma Aldrich (Burlington, MA, USA). No further purification was performed of the powder samples. The PXRD data were collected using a Rigaku diffractometer (Tokyo, Japan), operating with CuKα radiation (1.5406 Å) at 50 kV and 100 mA. The diffractograms were collected using a step scanning configuration between = 20°–100° for CeO2 and TiO2, with 0.02° and 5s per step. The crystallographic phases were identified using Match-Phase Identification from Powder Diffraction software (version3, Crystal Impact, Germany) using the crystallographic cards (96-434-3162) and (96-500-022) with the crystallographic information files (CIF) #9009008 and #5000223 for the CeO2 and TiO2 anatase phases, respectively. The OriginPro 9.0 software was used to estimate the FWHM, using a pseudo-Voigt fitting model corrected by the instrumental resolution function (IRF) obtained from the standard corundum (see Figure S1).
For the RM of the diffractograms, the software FullProf Suite (version July 2001) was employed, the CeO2 and TiO2 crystallographic information files (CIF) obtained from Match v3 software were used as initial parameters, which crystallographic data for CeO2 were cubic crystalline structure, space group Fm-3m, and cell parameter a = 5.4110 Å. For TiO2 anatase, they were tetragonal crystalline structure, space group I 41/amd, cell parameters a = 3.78435 Å and c = 9.50374 Å. For both cases the Caglioti initial parameters were U = 0.004133, V = −0.007618, and W = 0.006255. Refinement was done using the Thompson–Cox–Hastings (TCH) pseudo-Voigt Axial divergence asymmetry function. Finally, the average crystallite size was determined in the FullProf Suite program. To do that, we first characterized the Al2O3 standard. The used experimental conditions were = 10°–80° with a step of 0.02°. For the Al2O3 refinement, the TCH profile was employed to obtain the instrumental parameters of the equipment, which was added to the instrumental resolution file (IRF) and later used to determine the average crystallite sizes of the CeO2 and TiO2 NPs.
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