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Vacancy pairing and superstructure in the high-pressure silicate K1.5Mg2Si2O7H0.5: a new potential host for potassium in the deep Earth

Authors:

Welch, M. D.; Bindi, L.; Petricek, V.; Plasil, J.

Journal:

Acta Crystallographica Section B 72 822-827 (2016)

DOI:

https://doi.org/10.1107/S2052520616014049

B-IncStrDB ID: 12392EA3Waa Entry date: 2016-12-05 Last revision: 2022-02-12

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Chemical data

Structural Formula Sum: H0 K1.5 Mg2 O7 Si2 [ Help ]

Formula weight: 275.4 Da [ Help ]

Absolute configuration: . [ Help ]

Crystallographic data and experimental details

Crystal system: orthorhombic [ Help ]

Superspace group name: Cmcm(0β0)s00 [ Help ]

Symmetry operations of the superspace group: [ Help ]

Operation code Operation in algebraic form
1 x1,x2,x3,x4
2 -x1,-x2,x3+1/2,-x4
3 -x1,x2,-x3+1/2,x4+1/2
4 x1,-x2,-x3,-x4+1/2
5 -x1,-x2,-x3,-x4
6 x1,x2,-x3+1/2,x4
7 x1,-x2,x3+1/2,-x4+1/2
8 -x1,x2,x3,x4+1/2
9 x1+1/2,x2+1/2,x3,x4
10 -x1+1/2,-x2+1/2,x3+1/2,-x4
11 -x1+1/2,x2+1/2,-x3+1/2,x4+1/2
12 x1+1/2,-x2+1/2,-x3,-x4+1/2
13 -x1+1/2,-x2+1/2,-x3,-x4
14 x1+1/2,x2+1/2,-x3+1/2,x4
15 x1+1/2,-x2+1/2,x3+1/2,-x4+1/2
16 -x1+1/2,x2+1/2,x3,x4+1/2

a: 8.7623(10) Å [ Help ]

b: 5.0703(7) Å [ Help ]

c: 13.2505(11) Å [ Help ]

α: 90 ° [ Help ]

β: 90 ° [ Help ]

γ: 90 ° [ Help ]

Volume: 588.69(12) Å3 [ Help ]

Modulation dimension: 1 [ Help ]

Measured independent wave vectors: [ Help ]

Wave vector id q_x q_y q_z
1 0.000000 0.750000 0.000000

Z: 4 [ Help ]

Cell measurement temperature: 293 K [ Help ]

μ: 1.87 mm-1 [ Help ]

Minimum transmission factor: 0.907 [ Help ]

Maximum transmission factor: 1.000 [ Help ]

Refinement details

Total nb. of reflections: 6596 [ Help ]

Nb. of observed reflections: 2500 [ Help ]

Intense reflections threshold: I>3σ(I) [ Help ]

Refinement based on: F [ Help ]

R(obs): 0.0688 [ Help ]

wR(obs): 0.0826 [ Help ]

R(all): 0.1460 [ Help ]

wR(all): 0.1068 [ Help ]

S(all): 1.59 [ Help ]

S(obs): 2.00 [ Help ]

Nb. of reflections: 6596 [ Help ]

Nb. of parameters: 98 [ Help ]

Number of restraints: 0 [ Help ]

Number of constraints: 0 [ Help ]

Weighting scheme: sigma [ Help ]

Weighting scheme remarks: w=1/(σ2(F)+0.0001F2) [ Help ]

Refinement of hydrogen atoms: constr [ Help ]

Δ/σ(max): 0.0278 [ Help ]

Δ/σ(mean): 0.0027 [ Help ]

Extinction method: none [ Help ]

Structural Information

Average Structure: [ 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
Si1 Si 0 -0.0047(2) -0.12332(5) Uani 0.0042(4) 8 1 d . . .
K1 K 0.16177(9) 0.48790(16) -0.25 Uani 0.0104(2) 8 0.75 d . . .
Mg1 Mg 0.1650(2) 0.5 0 Uani 0.0063(4) 8 1 d . . .
O1 O 0 -0.0068(7) -0.25 Uiso 0.0060(6) 4 1 d . . .
O2 O -0.1559(2) 0.1517(5) -0.40896(13) Uiso 0.0059(4) 16 1 d . . .
O3 O 0 -0.3092(5) -0.41202(18) Uiso 0.0061(7) 8 1 d . . .

ADP components: [ Help ]

Atom site label Atom site symbol U11 U22 U33 U12 U13 U23
Si1 Si 0.0069(8) 0.0051(9) 0.0007(5) 0 0 0.0008(4)
K1 K 0.0124(4) 0.0137(5) 0.0051(4) -0.0011(3) 0 0
Mg1 Mg 0.0073(8) 0.0063(8) 0.0053(6) 0 0 -0.0009(5)

Fourier Wave Vectors (explicit: q_x,q_y,q_z or coefficients: q_1,q_2,...): [ Help ]

Wave vector code q_1
1 1
2 2
3 3
4 4

Occupation crenel coefficients: [ Help ]

Atom site label Center (x0) Width
K1 0.25 0.75

Definition of the displacive (translational) Fourier series: [ Help ]

Modulation code Atom site label Displacement axis Wave vector code
Si1x1 Si1 x 1
Si1y1 Si1 y 1
Si1z1 Si1 z 1
Si1x2 Si1 x 2
Si1y2 Si1 y 2
Si1z2 Si1 z 2
Si1x3 Si1 x 3
Si1y3 Si1 y 3
Si1z3 Si1 z 3
Si1x4 Si1 x 4
Si1y4 Si1 y 4
Si1z4 Si1 z 4
Mg1x1 Mg1 x 1
Mg1y1 Mg1 y 1
Mg1z1 Mg1 z 1
Mg1x2 Mg1 x 2
Mg1y2 Mg1 y 2
Mg1z2 Mg1 z 2
Mg1x3 Mg1 x 3
Mg1y3 Mg1 y 3
Mg1z3 Mg1 z 3
Mg1x4 Mg1 x 4
Mg1y4 Mg1 y 4
Mg1z4 Mg1 z 4
O1x1 O1 x 1
O1y1 O1 y 1
O1z1 O1 z 1
O1x2 O1 x 2
O1y2 O1 y 2
O1z2 O1 z 2
O1x3 O1 x 3
O1y3 O1 y 3
O1z3 O1 z 3
O1x4 O1 x 4
O1y4 O1 y 4
O1z4 O1 z 4
O2x1 O2 x 1
O2y1 O2 y 1
O2z1 O2 z 1
O2x2 O2 x 2
O2y2 O2 y 2
O2z2 O2 z 2
O2x3 O2 x 3
O2y3 O2 y 3
O2z3 O2 z 3
O2x4 O2 x 4
O2y4 O2 y 4
O2z4 O2 z 4
O3x1 O3 x 1
O3y1 O3 y 1
O3z1 O3 z 1
O3x2 O3 x 2
O3y2 O3 y 2
O3z2 O3 z 2
O3x3 O3 x 3
O3y3 O3 y 3
O3z3 O3 z 3
O3x4 O3 x 4
O3y4 O3 y 4
O3z4 O3 z 4

Displacive (translational) Fourier coefficients: [ Help ]

Modulation code Cosine coefficient Sine coefficient
Si1x1 0.00183(12) -0.00480(11)
Si1y1 0 0
Si1z1 0 0
Si1x2 0 0
Si1y2 0.0035(2) 0.00480(19)
Si1z2 0.00056(7) 0.00132(8)
Si1x3 -0.00704(12) -0.00541(11)
Si1y3 0 0
Si1z3 0 0
Si1x4 0 0
Si1y4 0 0.00156(13)
Si1z4 0 -0.00075(5)
Mg1x1 0 0.00470(13)
Mg1y1 -0.0056(2) 0
Mg1z1 -0.00077(10) 0
Mg1x2 0.00245(13) 0
Mg1y2 0 0.0141(2)
Mg1z2 0 -0.00036(10)
Mg1x3 0 -0.00792(13)
Mg1y3 0.0083(2) 0
Mg1z3 0.00123(10) 0
Mg1x4 0 0
Mg1y4 0 -0.00550(17)
Mg1z4 0 -0.00035(6)
O1x1 -0.0009(4) 0.0001(4)
O1y1 0 0
O1z1 0 0
O1x2 0 0
O1y2 0.0024(7) 0.0065(6)
O1z2 0 0
O1x3 -0.0061(4) -0.0065(4)
O1y3 0 0
O1z3 0 0
O1x4 0 0
O1y4 0 0.0060(5)
O1z4 0 0
O2x1 0.00074(19) -0.00016(18)
O2y1 -0.0015(3) 0.0015(3)
O2z1 0.00031(12) 0.00036(13)
O2x2 -0.00004(19) 0.00034(19)
O2y2 0.0000(3) 0.0010(3)
O2z2 0.00156(12) -0.00032(12)
O2x3 0.00721(19) 0.00103(18)
O2y3 -0.0001(3) -0.0037(3)
O2z3 0.00095(13) -0.00230(13)
O2x4 0 0.00024(13)
O2y4 0 -0.0048(2)
O2z4 0 -0.00123(9)
O3x1 0.0015(3) -0.0002(3)
O3y1 0 0
O3z1 0 0
O3x2 0 0
O3y2 0.0029(5) -0.0024(5)
O3z2 -0.00200(18) 0.00117(17)
O3x3 0.0071(3) 0.0013(3)
O3y3 0 0
O3z3 0 0
O3x4 0 0
O3y4 0 0.0020(4)
O3z4 0 0.00173(14)

Displacive (translational) Legendre coefficients: [ Help ]

Atom site label Displacement axis Polynomial order Polynomial coeff.
K1 x 1 0.00220(12)
K1 y 1 -0.0417(2)
K1 z 1 0
K1 x 2 -0.02975(12)
K1 y 2 0.0101(2)
K1 z 2 0
K1 x 3 0.00319(14)
K1 y 3 0.0224(2)
K1 z 3 0
K1 x 4 -0.00262(11)
K1 y 4 -0.0029(2)
K1 z 4 0
K1 x 5 -0.01812(17)
K1 y 5 -0.0048(3)
K1 z 5 0
K1 x 6 0
K1 y 6 0
K1 z 6 0