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The high-pressure silicate K1.5Mg2Si2O7H0.5, synthesized and characterized by Welch et al. [(2012), Am. Mineral. 97, 1849–1857], has been re-examined with the aim of determining the nature of the superstructure noted in their study. The composition corresponds to a 1:1 combination of KMg2Si2O7H and K2Mg2Si2O7 end-members, but it is not a solid solution. Single-crystal X-ray diffraction data for one of the original K1.5Mg2Si2O7H0.5 crystals synthesized at 16 GPa/1573 K, has been collected using a much longer exposure time in order to improve the intensity statistics of weak superlattice reflections identified by Welch et al. (2012). The superstructure has been determined using a superspace approach as having the superspace group Cmcm(0,β,0)00s and t0 = 1/16 with refined parameters a = 8.7623 (10), b = 5.0703 (7), c = 13.2505 (11) Å, V = 588.69 (12) Å3. This structure corresponds to one with the conventional space group Pbnm and unit-cell parameters a = 8.7623 (10), b = 20.281 (3), c = 13.2505 (11) Å, V = 2354.7 (5) Å3 and is based upon a super-sheet motif in which ordering involves rows of pairs of vacant interlayer K sites. This is the third topologically distinct structure type for the KMg2Si2O7H−K2Mg2Si2O7 join and suggests that there is very limited solid solution, and so it can be expected that each of the three structures (P63cm, P\bar 3 1m and Pbnm) has its own stability field, rather than being part of a continuous compositional series based upon a single structure type. As such, K1.5Mg2Si2O7H0.5 should be considered as a potentially significant host of K in the Earth's mantle.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S2052520616014049/xk5031sup1.cif
Contains datablock I

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S2052520616014049/xk5031sup2.cif
CIF containing the information for the Cmcm superstructure. File was created by JANA.

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S2052520616014049/xk5031Isup3.hkl
Contains datablock I

B-IncStrDB reference: 12392EA3Waa

CCDC reference: 1502345

Computing details top

(I) top
Crystal data top
K1.50Mg2O7Si2H0.5F(000) = 273
Mr = 275.45Dx = 3.128 Mg m3
a = 5.0535 (3) ÅMo Kα radiation, λ = 0.71073 Å
b = 5.0535 (3) ÅCell parameters from 1268 reflections
c = 13.2229 (6) Åθ = 4.7–26.9°
α = 90°µ = 1.88 mm1
β = 90°T = 293 K
γ = 120°Plate, colourless
V = 292.45 (3) Å30.23 × 0.16 × 0.06 mm
Z = 2
Data collection top
Excalibur EOS detector Agilent Technologies
diffractometer
143 independent reflections
Radiation source: fine-focus sealed tube143 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.024
1K CCD–based area detector scansθmax = 27.3°, θmin = 3.1°
Absorption correction: multi-scanh = 66
Tmin = 0.688, Tmax = 1.000k = 66
2759 measured reflectionsl = 1616
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.030Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.083H atoms treated by a mixture of independent and constrained refinement
S = 1.45 w = 1/[σ2(Fo2) + (0.0307P)2 + 0.5285P]
where P = (Fo2 + 2Fc2)/3
143 reflections(Δ/σ)max < 0.001
21 parametersΔρmax = 0.34 e Å3
0 restraintsΔρmin = 0.38 e Å3
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > 2sigma(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
K0.342 (10)0.636 (3)0.25000.026 (5)0.2452 (19)
Mg0.33330.66670.00000.0122 (5)
Si0.00000.00000.12314 (9)0.0083 (5)
O10.00000.00000.25000.0123 (12)
O20.3099 (4)0.00000.41003 (13)0.0100 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
K0.030 (13)0.014 (7)0.0067 (8)0.009 (5)0.0000.000
Mg0.0142 (7)0.0142 (7)0.0082 (8)0.0071 (3)0.0000.000
Si0.0106 (6)0.0106 (6)0.0037 (7)0.0053 (3)0.0000.000
O10.0169 (18)0.0169 (18)0.003 (2)0.0085 (9)0.0000.000
O20.0105 (8)0.0122 (11)0.0078 (9)0.0061 (5)0.0007 (7)0.000
Geometric parameters (Å, º) top
K—Ki0.31 (7)Si—O11.6774 (12)
K—Kii0.31 (7)Si—Kiii3.251 (9)
K—Kiii2.57 (10)Si—Kxxi3.251 (9)
K—O2iv2.68 (3)Si—Kxxii3.251 (9)
K—O2v2.68 (3)Si—Kxxiii3.251 (9)
K—O2vi2.707 (18)Si—Kxxiv3.251 (9)
K—O2iii2.707 (18)Si—Kii3.34 (4)
K—O12.785 (11)Si—Kxxv3.34 (4)
K—Kvii2.792 (9)O1—Sixx1.6774 (12)
K—Kviii2.792 (9)O1—Kxxiii2.785 (11)
K—O2ix2.86 (2)O1—Kxxiv2.785 (11)
K—O2x2.86 (2)O1—Kiii2.785 (11)
Mg—O2xi2.1133 (13)O1—Kxxi2.785 (11)
Mg—O2x2.1133 (13)O1—Kxxii2.785 (11)
Mg—O2vi2.1133 (13)O1—Kxxvi2.89 (4)
Mg—O2xii2.1133 (13)O1—Kxxvii2.89 (4)
Mg—O2xiii2.1133 (13)O1—Kii2.89 (4)
Mg—O2v2.1133 (13)O1—Kxxv2.89 (4)
Mg—Mgxiv2.9177 (2)O2—Sixx1.626 (2)
Mg—Mgxv2.9177 (2)O2—Mgxxviii2.1133 (13)
Mg—Mgxvi2.9177 (2)O2—Mgxxix2.1133 (13)
Mg—Kxvii3.311 (2)O2—Kxxx2.68 (3)
Mg—Ki3.311 (2)O2—Kxxv2.68 (3)
Mg—Kxviii3.311 (2)O2—Kxxi2.707 (18)
Si—O2xix1.626 (2)O2—Kiii2.707 (18)
Si—O2vi1.626 (2)O2—Kxxxi2.86 (2)
Si—O2xx1.626 (2)O2—Kviii2.86 (2)
Ki—K—Kii60.00 (4)O1—Si—Kxxi58.94 (10)
Ki—K—Kiii132 (10)K—Si—Kxxi95.78 (13)
Kii—K—Kiii168 (10)Kiii—Si—Kxxi54.8 (18)
Ki—K—O2iv92 (7)O2xix—Si—Kxxii95.9 (9)
Kii—K—O2iv123 (3)O2vi—Si—Kxxii56.2 (6)
Kiii—K—O2iv61.3 (8)O2xx—Si—Kxxii150.6 (9)
Ki—K—O2v92 (7)O1—Si—Kxxii58.94 (10)
Kii—K—O2v123 (3)K—Si—Kxxii54.8 (18)
Kiii—K—O2v61.3 (8)Kiii—Si—Kxxii95.78 (13)
O2iv—K—O2v104.5 (18)Kxxi—Si—Kxxii117.7 (3)
Ki—K—O2vi116 (6)O2xix—Si—Kxxiii56.2 (6)
Kii—K—O2vi81 (9)O2vi—Si—Kxxiii95.9 (9)
Kiii—K—O2vi91.5 (10)O2xx—Si—Kxxiii150.6 (9)
O2iv—K—O2vi150.1 (13)O1—Si—Kxxiii58.94 (10)
O2v—K—O2vi68.4 (2)K—Si—Kxxiii95.78 (13)
Ki—K—O2iii116 (6)Kiii—Si—Kxxiii117.7 (3)
Kii—K—O2iii81 (9)Kxxi—Si—Kxxiii95.78 (13)
Kiii—K—O2iii91.5 (10)Kxxii—Si—Kxxiii46.6 (18)
O2iv—K—O2iii68.4 (2)O2xix—Si—Kxxiv56.2 (6)
O2v—K—O2iii150.1 (13)O2vi—Si—Kxxiv150.6 (9)
O2vi—K—O2iii102.8 (9)O2xx—Si—Kxxiv95.9 (9)
Ki—K—O1166 (10)O1—Si—Kxxiv58.94 (10)
Kii—K—O1106 (10)K—Si—Kxxiv117.7 (3)
Kiii—K—O162.5 (11)Kiii—Si—Kxxiv95.78 (13)
O2iv—K—O196.6 (8)Kxxi—Si—Kxxiv46.6 (18)
O2v—K—O196.6 (8)Kxxii—Si—Kxxiv95.78 (13)
O2vi—K—O157.3 (3)Kxxiii—Si—Kxxiv54.8 (18)
O2iii—K—O157.3 (3)O2xix—Si—Kii146.0 (6)
Ki—K—Kvii103 (10)O2vi—Si—Kii52.43 (14)
Kii—K—Kvii43 (10)O2xx—Si—Kii100.8 (6)
Kiii—K—Kvii124.8 (4)O1—Si—Kii59.8 (4)
O2iv—K—Kvii125.9 (8)K—Si—Kii5.3 (14)
O2v—K—Kvii125.9 (8)Kiii—Si—Kii51.8 (5)
O2vi—K—Kvii58.2 (10)Kxxi—Si—Kii100.2 (8)
O2iii—K—Kvii58.2 (10)Kxxii—Si—Kii50.1 (3)
O1—K—Kvii62.3 (11)Kxxiii—Si—Kii92.4 (14)
Ki—K—Kviii127 (10)Kxxiv—Si—Kii118.8 (4)
Kii—K—Kviii173 (10)O2xix—Si—Kxxv146.0 (6)
Kiii—K—Kviii4.8 (4)O2vi—Si—Kxxv100.8 (6)
O2iv—K—Kviii59.3 (8)O2xx—Si—Kxxv52.43 (14)
O2v—K—Kviii59.3 (8)O1—Si—Kxxv59.8 (4)
O2vi—K—Kviii94.5 (11)K—Si—Kxxv51.8 (5)
O2iii—K—Kviii94.5 (11)Kiii—Si—Kxxv5.3 (14)
O1—K—Kviii67.3 (12)Kxxi—Si—Kxxv50.1 (3)
Kvii—K—Kviii129.6 (8)Kxxii—Si—Kxxv100.2 (8)
Ki—K—O2ix51 (4)Kxxiii—Si—Kxxv118.8 (4)
Kii—K—O2ix58 (5)Kxxiv—Si—Kxxv92.4 (14)
Kiii—K—O2ix127.3 (9)Kii—Si—Kxxv57.1 (8)
O2iv—K—O2ix66.12 (14)Si—O1—Sixx180.0
O2v—K—O2ix139.8 (7)Si—O1—K90.000 (7)
O2vi—K—O2ix138 (2)Sixx—O1—K90.000 (7)
O2iii—K—O2ix65.7 (5)Si—O1—Kxxiii90.000 (7)
O1—K—O2ix122.7 (8)Sixx—O1—Kxxiii90.000 (7)
Kvii—K—O2ix84.0 (10)K—O1—Kxxiii120.000 (2)
Kviii—K—O2ix125.4 (9)Si—O1—Kxxiv90.000 (7)
Ki—K—O2x51 (4)Sixx—O1—Kxxiv90.000 (7)
Kii—K—O2x58 (5)K—O1—Kxxiv175 (2)
Kiii—K—O2x127.3 (9)Kxxiii—O1—Kxxiv65 (2)
O2iv—K—O2x139.8 (7)Si—O1—Kiii90.000 (7)
O2v—K—O2x66.12 (14)Sixx—O1—Kiii90.000 (7)
O2vi—K—O2x65.7 (5)K—O1—Kiii55 (2)
O2iii—K—O2x138 (2)Kxxiii—O1—Kiii175 (2)
O1—K—O2x122.7 (8)Kxxiv—O1—Kiii120.000 (2)
Kvii—K—O2x84.0 (10)Si—O1—Kxxi90.000 (1)
Kviii—K—O2x125.4 (9)Sixx—O1—Kxxi90.000 (1)
O2ix—K—O2x95.4 (10)K—O1—Kxxi120.000 (11)
O2xi—Mg—O2x84.74 (11)Kxxiii—O1—Kxxi120.000 (11)
O2xi—Mg—O2vi92.69 (7)Kxxiv—O1—Kxxi55 (2)
O2x—Mg—O2vi91.41 (6)Kiii—O1—Kxxi65 (2)
O2xi—Mg—O2xii91.41 (6)Si—O1—Kxxii90.000 (1)
O2x—Mg—O2xii92.69 (7)Sixx—O1—Kxxii90.000 (1)
O2vi—Mg—O2xii174.44 (10)K—O1—Kxxii65 (2)
O2xi—Mg—O2xiii91.41 (6)Kxxiii—O1—Kxxii55 (2)
O2x—Mg—O2xiii174.44 (10)Kxxiv—O1—Kxxii120.000 (14)
O2vi—Mg—O2xiii84.74 (11)Kiii—O1—Kxxii120.000 (13)
O2xii—Mg—O2xiii91.41 (6)Kxxi—O1—Kxxii175 (2)
O2xi—Mg—O2v174.44 (10)Si—O1—Kxxvi90.000 (7)
O2x—Mg—O2v91.41 (6)Sixx—O1—Kxxvi90.000 (7)
O2vi—Mg—O2v91.41 (6)K—O1—Kxxvi126.0 (17)
O2xii—Mg—O2v84.74 (11)Kxxiii—O1—Kxxvi6.0 (17)
O2xiii—Mg—O2v92.69 (7)Kxxiv—O1—Kxxvi59.0 (5)
O2xi—Mg—Mgxiv87.22 (5)Kiii—O1—Kxxvi179.0 (5)
O2x—Mg—Mgxiv46.35 (3)Kxxi—O1—Kxxvi114.0 (17)
O2vi—Mg—Mgxiv137.63 (5)Kxxii—O1—Kxxvi61.0 (5)
O2xii—Mg—Mgxiv46.35 (3)Si—O1—Kxxvii90.000 (7)
O2xiii—Mg—Mgxiv137.63 (5)Sixx—O1—Kxxvii90.000 (7)
O2v—Mg—Mgxiv87.22 (5)K—O1—Kxxvii179.0 (5)
O2xi—Mg—Mgxv46.35 (3)Kxxiii—O1—Kxxvii59.0 (5)
O2x—Mg—Mgxv87.22 (5)Kxxiv—O1—Kxxvii6.0 (17)
O2vi—Mg—Mgxv46.35 (3)Kiii—O1—Kxxvii126.0 (17)
O2xii—Mg—Mgxv137.63 (5)Kxxi—O1—Kxxvii61.0 (5)
O2xiii—Mg—Mgxv87.22 (5)Kxxii—O1—Kxxvii114.0 (17)
O2v—Mg—Mgxv137.63 (5)Kxxvi—O1—Kxxvii52.9 (13)
Mgxiv—Mg—Mgxv120.0Si—O1—Kii90.000 (14)
O2xi—Mg—Mgxvi137.63 (5)Sixx—O1—Kii90.000 (14)
O2x—Mg—Mgxvi137.63 (5)K—O1—Kii6.0 (17)
O2vi—Mg—Mgxvi87.22 (5)Kxxiii—O1—Kii114.0 (17)
O2xii—Mg—Mgxvi87.22 (5)Kxxiv—O1—Kii179.0 (5)
O2xiii—Mg—Mgxvi46.35 (3)Kiii—O1—Kii61.0 (5)
O2v—Mg—Mgxvi46.35 (3)Kxxi—O1—Kii126.0 (17)
Mgxiv—Mg—Mgxvi120.0Kxxii—O1—Kii59.0 (5)
Mgxv—Mg—Mgxvi120.0Kxxvi—O1—Kii120.000 (4)
O2xi—Mg—Kxvii53.8 (9)Kxxvii—O1—Kii172.9 (13)
O2x—Mg—Kxvii125.0 (5)Si—O1—Kxxv90.000 (14)
O2vi—Mg—Kxvii121.2 (5)Sixx—O1—Kxxv90.000 (14)
O2xii—Mg—Kxvii58.9 (6)K—O1—Kxxv61.0 (5)
O2xiii—Mg—Kxvii54.6 (4)Kxxiii—O1—Kxxv179.0 (5)
O2v—Mg—Kxvii126.5 (9)Kxxiv—O1—Kxxv114.0 (17)
Mgxiv—Mg—Kxvii92.34 (19)Kiii—O1—Kxxv6.0 (17)
Mgxv—Mg—Kxvii87.0 (8)Kxxi—O1—Kxxv59.0 (5)
Mgxvi—Mg—Kxvii90.7 (8)Kxxii—O1—Kxxv126.0 (17)
O2xi—Mg—Ki125.0 (5)Kxxvi—O1—Kxxv172.9 (13)
O2x—Mg—Ki53.8 (9)Kxxvii—O1—Kxxv120.000 (3)
O2vi—Mg—Ki58.9 (6)Kii—O1—Kxxv67.1 (13)
O2xii—Mg—Ki121.2 (5)Sixx—O2—Mgxxviii126.12 (7)
O2xiii—Mg—Ki126.5 (9)Sixx—O2—Mgxxix126.12 (7)
O2v—Mg—Ki54.6 (4)Mgxxviii—O2—Mgxxix87.31 (7)
Mgxiv—Mg—Ki87.0 (8)Sixx—O2—Kxxx98.8 (5)
Mgxv—Mg—Ki92.34 (19)Mgxxviii—O2—Kxxx127.2 (3)
Mgxvi—Mg—Ki90.7 (8)Mgxxix—O2—Kxxx86.6 (9)
Kxvii—Mg—Ki178.7 (16)Sixx—O2—Kxxv98.8 (5)
O2xi—Mg—Kxviii54.6 (4)Mgxxviii—O2—Kxxv86.6 (9)
O2x—Mg—Kxviii121.2 (5)Mgxxix—O2—Kxxv127.2 (3)
O2vi—Mg—Kxviii126.5 (9)Kxxx—O2—Kxxv57.4 (16)
O2xii—Mg—Kxviii53.8 (9)Sixx—O2—Kxxi93.9 (6)
O2xiii—Mg—Kxviii58.9 (6)Mgxxviii—O2—Kxxi133.6 (10)
O2v—Mg—Kxviii125.0 (5)Mgxxix—O2—Kxxi85.8 (4)
Mgxiv—Mg—Kxviii87.0 (8)Kxxx—O2—Kxxi6.7 (13)
Mgxv—Mg—Kxviii90.7 (8)Kxxv—O2—Kxxi62.5 (2)
Mgxvi—Mg—Kxviii92.34 (19)Sixx—O2—Kiii93.9 (6)
Kxvii—Mg—Kxviii5.5 (11)Mgxxviii—O2—Kiii85.8 (4)
Ki—Mg—Kxviii174.0 (17)Mgxxix—O2—Kiii133.6 (10)
O2xix—Si—O2vi113.01 (6)Kxxx—O2—Kiii62.5 (2)
O2xix—Si—O2xx113.01 (6)Kxxv—O2—Kiii6.7 (13)
O2vi—Si—O2xx113.01 (6)Kxxi—O2—Kiii67.1 (18)
O2xix—Si—O1105.65 (7)Sixx—O2—Kxxxi99.5 (10)
O2vi—Si—O1105.65 (7)Mgxxviii—O2—Kxxxi129.0 (9)
O2xx—Si—O1105.65 (7)Mgxxix—O2—Kxxxi81.9 (5)
O2xix—Si—K150.6 (9)Kxxx—O2—Kxxxi5.3 (9)
O2vi—Si—K56.2 (6)Kxxv—O2—Kxxxi62.6 (10)
O2xx—Si—K95.9 (9)Kxxi—O2—Kxxxi5.6 (14)
O1—Si—K58.94 (10)Kiii—O2—Kxxxi67.7 (8)
O2xix—Si—Kiii150.6 (9)Sixx—O2—Kviii99.5 (10)
O2vi—Si—Kiii95.9 (9)Mgxxviii—O2—Kviii81.9 (5)
O2xx—Si—Kiii56.2 (6)Mgxxix—O2—Kviii129.0 (9)
O1—Si—Kiii58.94 (10)Kxxx—O2—Kviii62.6 (10)
K—Si—Kiii46.6 (18)Kxxv—O2—Kviii5.3 (9)
O2xix—Si—Kxxi95.9 (9)Kxxi—O2—Kviii67.7 (9)
O2vi—Si—Kxxi150.6 (9)Kiii—O2—Kviii5.6 (14)
O2xx—Si—Kxxi56.2 (6)Kxxxi—O2—Kviii67.7 (6)
Symmetry codes: (i) y+1, xy+1, z; (ii) x+y, x+1, z+1/2; (iii) y, x, z; (iv) x+1, x+y+1, z; (v) x+1, x+y+1, z+1/2; (vi) y, x, z+1/2; (vii) xy, y+1, z+1/2; (viii) xy+1, y+1, z+1/2; (ix) x, y+1, z; (x) x, y+1, z+1/2; (xi) y, x+1, z1/2; (xii) x+1, y+1, z1/2; (xiii) x, xy, z1/2; (xiv) x+1, y+2, z; (xv) x, y+1, z; (xvi) x+1, y+1, z; (xvii) x+y, y, z1/2; (xviii) x, xy+1, z; (xix) x, x+y, z+1/2; (xx) x, y, z+1/2; (xxi) x+y, x, z+1/2; (xxii) x, x+y, z; (xxiii) y, xy, z; (xxiv) xy, y, z+1/2; (xxv) x+1, x+y, z; (xxvi) x1, y1, z; (xxvii) y1, x1, z; (xxviii) x+1, y+1, z+1/2; (xxix) x, y1, z+1/2; (xxx) y+1, xy, z; (xxxi) x, y1, z.
 
(I) top
Crystal data top
H0K1.5Mg2O7Si2Z = 4
Mr = 275.4F(000) = 546
Orthorhombic, Cmcm(0β0)s00†Dx = 3.108 Mg m3
q = 0.750000b*Mo Kα radiation, λ = 0.71069 Å
a = 8.7623 (10) ŵ = 1.87 mm1
b = 5.0703 (7) ÅT = 293 K
c = 13.2505 (11) ÅPlate, colourless
V = 588.69 (12) Å30.24 × 0.18 × 0.06 mm
† Symmetry operations: (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.

Data collection top
Xcalibur
diffractometer
2500 reflections with I > 3σ(I)
Radiation source: X-ray tubeh = 1111
Graphite monochromatork = 77
19703 measured reflectionsl = 1716
6596 independent reflections
Refinement top
Refinement on F0 restraints
R[F2 > 2σ(F2)] = 0.0690 constraints
wR(F2) = 0.107H-atom parameters constrained
S = 1.59Weighting scheme based on measured s.u.'s w = 1/(σ2(F) + 0.0001F2)
6596 reflections(Δ/σ)max = 0.028
98 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Si100.0047 (2)0.12332 (5)0.0042 (4)
K10.16177 (9)0.48790 (16)0.250.0104 (2)0.75
Mg10.1650 (2)0.500.0063 (4)
O100.0068 (7)0.250.0060 (6)*
O20.1559 (2)0.1517 (5)0.40896 (13)0.0059 (4)*
O300.3092 (5)0.41202 (18)0.0061 (7)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Si10.0069 (8)0.0051 (9)0.0007 (5)000.0008 (4)
K10.0124 (4)0.0137 (5)0.0051 (4)0.0011 (3)00
Mg10.0073 (8)0.0063 (8)0.0053 (6)000.0009 (5)
 

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