| RModel [Å] | V2O5 | hydrated VxOy-SBA-15 |
---|
Type |
N
| RModel [Å] | R[Å] | σ2 [Å2] | R[Å] | σ2 [Å2] |
---|
V - O | 1 | 1.58 | 1.58 | 0.0104 | 1.65 | 0.0126 |
V - O | 1 | 1.78 | 1.88 | 0.0104C | 1.92 | 0.0126C |
V - O | 2 | 1.88 | 1.88C | 0.0104C | 1.92C | 0.0126C |
V - O | 1 | 2.02 | 1.88C | 0.0104C | 1.92C | 0.0126C |
V - V | 2 | 3.08 | 3.11 | 0.0047 | 3.08 | 0.0129 |
V - V | 1 | 3.43 | 3.39 | 0.0047C | 3.43 | 0.0129C |
V - V | 2 | 3.56 | 3.59 | 0.0047C | 3.65 | 0.0129C |
- Type and number (N) of atoms at distance R from the V atoms in a V2O5 system compared to experimental distances and XAFS disorder parameter (σ2). Parameters were obtained from refinement of a V2O5 model structure (ICSD 60767) to the experimental V K edge XAFS FT(χ(k)*k3) of hydrated VxOy/SBA-15 (10.8 wt %) and bulk V2O5(). (k range from 2.7 - 11.0 Å-1, R range 0.9 - 3.8 Å, E0 (VxOy/SBA-15) = 0.0 eV/E0 (V2O5) = 0.0, fit residual 13.4 (VxOy/SBA-15) and 6.3 (V2O5), Nind = 18, Nfree = 7) (Subscript C indicates parameters that were correlated in the refinement). Confidence limits and significance of fitting parameters are given in Table 5.