Table 1.
Synoptic results of the conventional Rietveld refinement approach to size/shape determination, obtained by TOPAS according to an isotropic (Iso) and anisotropic (Aniso) morphological description of anatase. A single isotropic Debye–Waller factor was refined for all atoms in P25 (B = 0.53 or 0.49 Å2) and P90 (B = 0.58 or 0.51 Å2; for the Iso and Aniso models, respectively). <CS> = average crystal size; M and N subscripts = mass and number based.
| Parameter | P90 | P25 | ||
|---|---|---|---|---|
| Anatase | Rutile | Anatase | Rutile | |
| a, c (Å) | 3.7863, 9.4985 | 4.5947, 2.9592 | 3.7860, 9.5080 | 4.5947, 2.9592 |
| <CS>M (Iso, Aniso) (nm) | 15.6, 15.0 | 23.0, 23.0 | 26.8, 26.2 | 45.0, 45.3 |
| <CS>N (Nominal) (nm) | 14 | 21 | ||
| AR | 0.85 | - | 0.80 | - |
| wt (Iso, Aniso) % | 91.8, 91.8 | 8.2, 8.2 | 88.3, 88.4 | 11.7, 11.6 |
| RBragg (Iso, Aniso) | 2.4, 1.8 | 2.7, 2.5 | 2.1, 1.6 | 3.5, 3.1 |
| Rwp (Iso, Aniso) | 5.2, 4.5 | 5.8, 4.8 | ||