Table 2. Geometric parameters of (Mg2.53Fe0.47)C3O9 at 98 GPa.
| Group | Maximal bond length (Å) | Minimal bond length (Å) | Polyhedron volume (Å3) | Distortion indexa |
|---|---|---|---|---|
| CO4 (C1—O) | 1.409 (19) | 1.287 (18) | 1.25 | 0.045 |
| CO4 (C2—O) | 1.38 (3) | 1.29 (4) | 1.25 | 0.022 |
| M2O6 b | 1.87 (3) | 1.813 (10) | 7.78 | 0.010 |
| M1O8 c | 2.039 (13) | 1.908 (14) | 13.24 | 0.020 |
| M3O8 d | 2.358 (14)e | 1.828 (19) | 14.59 | 0.068 |
Notes: (a) as defined in Baur (1974 ▸); (b) Mg:Fe ratio for M = 1:0; (c) Mg:Fe ratio for M = 0.917 (17):0.083 (17); (d) Mg:Fe ratio for M = 0.61 (2):0.39 (2); (e) alternatively, for CN = 10 the maximal distance is 2.451 (14) Å, the polyhedral volume is 20.58 Å3 and the distortion index is 0.080.