Modulated structure of La2Co1.7 from neutron and X-ray diffraction data
Authors:Dusek, Michal; Chapuis, Gervais; Schobinger-Papamantellos, Penelope; Wilkinson, Clive; Petricek, Vaclav; Tung, L.D.; Buschow, Karl Heinz Juergen
Journal:Acta Crystallographica Section B 56 959-971 (2000)
DOI:https://doi.org/10.1107/S0108768100011332
B-IncStrDB ID: 5452E0wh9M Entry date: 2011-11-25 Last revision: 2022-01-02
I
Chemical data
Structural Formula Sum: Co3.594 La4 [ Help ]
Formula weight: 767.4 Da [ Help ]
Crystallographic data and experimental details
Crystal system: monoclinic [ Help ]
Superspace group name: C2/m(α0γ)00 [ Help ]
Symmetry operations of the superspace group: (Show/hide table) [ Help ]
| Operation code | Operation in algebraic form |
|---|---|
| 1 | x1,x2,x3,x4 |
| 2 | -x1,x2,-x3,-x4 |
| 3 | -x1,-x2,-x3,-x4 |
| 4 | x1,-x2,x3,x4 |
| 5 | x1+1/2,x2+1/2,x3,x4 |
| 6 | -x1+1/2,x2+1/2,-x3,-x4 |
| 7 | -x1+1/2,-x2+1/2,-x3,-x4 |
| 8 | x1+1/2,-x2+1/2,x3,x4 |
a: 8.4611 Å [ Help ]
b: 4.885 Å [ Help ]
c: 4.273 Å [ Help ]
α: 90 ° [ Help ]
β: 90 ° [ Help ]
γ: 90 ° [ Help ]
Volume: 176.614 Å3 [ Help ]
Modulation dimension: 1 [ Help ]
Measured independent wave vectors: (Show/hide table) [ Help ]
| Wave vector id | q_x | q_y | q_z |
|---|---|---|---|
| 1 | 0.226 | 0 | 0.203 |
Number of subsystems: 2 [ Help ]
Subsystem code: 1 [ Help ]
Subsystem description: 1st subsystem [ Help ]
W matrix:
| 1.0 | 0.0 | 0.0 | 0.0 |
| 0.0 | 1.0 | 0.0 | 0.0 |
| 0.0 | 0.0 | 1.0 | 0.0 |
| 0.0 | 0.0 | 0.0 | 1.0 |
Subsystem code: 2 [ Help ]
Subsystem description: 2nd subsystem [ Help ]
W matrix:
| 1.0 | 0.0 | 0.0 | 0.0 |
| 0.0 | 1.0 | 0.0 | 0.0 |
| 0.0 | 0.0 | 2.0 | -1.0 |
| 0.0 | 0.0 | -1.0 | 1.0 |
Z: 1 [ Help ]
μ: 0.053 mm-1 [ Help ]
Refinement details
Total nb. of reflections: 1901 [ Help ]
Nb. of observed reflections: 1284 [ Help ]
Intense reflections threshold: I>3σ(I) [ Help ]
Refinement based on: F [ Help ]
R(obs): 0.1006 [ Help ]
wR(obs): 0.1382 [ Help ]
R(all): 0.1454 [ Help ]
wR(all): 0.1498 [ Help ]
S(all): 3.26 [ Help ]
S(obs): 3.65 [ Help ]
Nb. of reflections: 1901 [ Help ]
Nb. of parameters: 20 [ Help ]
Weighting scheme: sigma [ Help ]
Weighting scheme remarks: w=1/(σ2(F)+0.0004F2) [ Help ]
Δ/σ(max): 0.0125 [ Help ]
Δ/σ(mean): 0.0041 [ Help ]
Extinction method: none [ Help ]
Structural Information
Average Structure: (Show/hide table) [ Help ]
| Atom site label | Atom symbol | x | y | z | ADP type | Uiso/equiv | Symmetry multiplicity | Occupancy | Coords from (d)iffraction or (c)alculated | Coords restraints or constraints | Disordered cluster | Disordered group | Subsystem |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| La1 | La | 0.1682(2) | 0.5 | 0.2535(4) | Uani | 0.0028(5) | 4 | 1 | d | ? | ? | ? | 1 |
| Co1 | Co | 0 | 0 | 0.5 | Uani | 0.0159(18) | 2 | 1 | d | ? | ? | ? | 2 |
ADP components: (Show/hide table) [ Help ]
| Atom site label | Atom site symbol | U11 | U22 | U33 | U12 | U13 | U23 |
|---|---|---|---|---|---|---|---|
| La1 | La | 0.0009(10) | 0.0031(10) | 0.0045(5) | 0 | -0.0008(7) | 0 |
| Co1 | Co | 0.0077(14) | -0.0016(12) | 0.041(5) | 0 | 0.0014(12) | 0 |
Fourier Wave Vectors (explicit: q_x,q_y,q_z or coefficients: q_1,q_2,...): (Show/hide table) [ Help ]
| Wave vector code | q_1 |
|---|---|
| 1 | 1 |
Definition of the displacive (translational) Fourier series: (Show/hide table) [ Help ]
| Modulation code | Atom site label | Displacement axis | Wave vector code |
|---|---|---|---|
| la1x1 | La1 | x | 1 |
| la1y1 | La1 | y | 1 |
| la1z1 | La1 | z | 1 |
Displacive (translational) Fourier coefficients: (Show/hide table) [ Help ]
| Modulation code | Cosine coefficient | Sine coefficient |
|---|---|---|
| la1x1 | -0.00094(16) | 0.00606(18) |
| la1y1 | 0 | 0 |
| la1z1 | 0.0006(3) | -0.0234(3) |