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Monophosphate tungsten bronze with pentagonal tunnels (PO2)4(WO3)2m are low-dimensional materials with charge density wave (CDW)-type electron instabilities. Two forms of the structure can thus be expected for all the members of the series: a low-temperature form (LT) corresponding to the CDW state and a high-temperature form (HT) corresponding to a normal metallic state. The HT form is described here for m = 9 and compared with that of the m = 5 and m = 7 counterparts. It is shown that a systematic twin phenomenon must be taken into account for HT members because of two possible configurations of the tilting mode of WO6 octahedra. The structure is also compared with that of m = 10, which exhibits the modulated CDW–LT form at room temperature. Owing to two possible polarization directions of the segments built of m WO6 octahedra, a twin phenomenon is also encountered in the LT forms. A review of all the structures known at present (m = 2, 4, 5, 6, 7, 8, 9, 10, 12) leads us to propose a structural law based on the building mode of WO6 octahedra in WO3-type slabs to explain the symmetry changes observed between even and odd members of the series.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108768199016195/lc0016sup1.cif
Contains datablock LC0016

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108768199016195/lc0016sup2.hkl
Supplementary material

Computing details top

Data collection: CAD4 (Enraf Nonius, 1980); cell refinement: SET4 (Enraf Nonius, 1989).

Figures top
[Figure 1]
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[Figure 8]
[Figure 9]
[Figure 10]
[Figure 11]
[Figure 12]
[Figure 13]
[Figure 14]
[Figure 15]
[Figure 16]
[Figure 17]
(LC0016) top
Crystal data top
O62P4W18Z = 1
Mr = 4425.1F(000) = 1888
Triclinic, P1Dx = 6.477 Mg m3
a = 5.2945 (9) ÅMo Kα radiation, λ = 0.71073 Å
b = 6.542 (2) ÅCell parameters from 17 reflections
c = 32.744 (5) Åθ = 5–43°
α = 90.00 (2)°µ = 45.71 mm1
β = 90.20 (2)°T = 293 K
γ = 89.78 (2)°Platelet, dark blue
V = 1134.2 (4) Å3158 × 144 × 4 mm
Data collection top
Enraf Nonius CAD4
diffractometer
θmax = 45°, θmin = 2°
type 2 scansh = 010
Absorption correction: gaussian
?
k = 1212
Tmin = 0.148, Tmax = 0.833l = 6464
20410 measured reflections3 standard reflections every 60 min
20041 independent reflections intensity decay: <4%
4661 reflections with I > 3σ(I)
Refinement top
Refinement on F200 parameters
R[F2 > 2σ(F2)] = 0.057Weighting scheme based on measured s.u.'s w = 1/σ2(F)
wR(F2) = 0.047(Δ/σ)max = 0.001
S = 2.79Δρmax = 1.44 e Å3
4661 reflectionsΔρmin = 1.34 e Å3
Crystal data top
O62P4W18γ = 89.78 (2)°
Mr = 4425.1V = 1134.2 (4) Å3
Triclinic, P1Z = 1
a = 5.2945 (9) ÅMo Kα radiation
b = 6.542 (2) ŵ = 45.71 mm1
c = 32.744 (5) ÅT = 293 K
α = 90.00 (2)°158 × 144 × 4 mm
β = 90.20 (2)°
Data collection top
Enraf Nonius CAD4
diffractometer
20041 independent reflections
Absorption correction: gaussian
?
4661 reflections with I > 3σ(I)
Tmin = 0.148, Tmax = 0.8333 standard reflections every 60 min
20410 measured reflections intensity decay: <4%
Refinement top
R[F2 > 2σ(F2)] = 0.057200 parameters
wR(F2) = 0.047Δρmax = 1.44 e Å3
S = 2.79Δρmin = 1.34 e Å3
4661 reflections
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
W1a0.0038 (2)0.3258 (2)0.81485 (3)0.0084 (3)
W2a0.4992 (2)0.0139 (2)0.86117 (4)0.0092 (3)
W3a0.0040 (2)0.3425 (2)0.90852 (4)0.0107 (3)
W4a0.4996 (2)0.3287 (2)0.04583 (4)0.0110 (4)
W5a0.00.00.00.0120 (5)
W1b0.5061 (2)0.8257 (1)0.68501 (4)0.0071 (3)
W2b0.0083 (2)0.4876 (2)0.63874 (4)0.0097 (3)
W3b0.5021 (2)0.1572 (2)0.59152 (4)0.0104 (3)
W4b0.0023 (2)0.8289 (2)0.54569 (4)0.0115 (4)
W5b1.50.50.50.0115 (4)
Pa0.499 (1)0.3636 (8)0.7832 (2)0.0008 (9)
Pb0.011 (1)0.1369 (9)0.7173 (2)0.004 (1)
O1a0.239 (3)0.531 (2)0.7873 (5)0.018 (4)
O2a0.7320.4890.79270.013
O3a0.0130.2080.75960.013
O4a0.998 (4)0.497 (3)0.8578 (7)0.021 (5)
O5a0.783 (3)0.142 (2)0.8367 (5)0.008 (3)
O6a0.276 (4)0.175 (3)0.8321 (6)0.023 (4)
O7a0.511 (4)0.169 (3)0.8088 (7)0.019 (5)
O8a0.501 (3)0.163 (2)0.9041 (6)0.008 (4)
O9a0.721 (3)0.192 (2)0.8836 (5)0.008 (3)
O10a0.214 (3)0.147 (2)0.8797 (5)0.016 (3)
O11a0.998 (3)0.166 (3)0.9519 (6)0.010 (4)
O12a0.789 (3)0.533 (2)0.9330 (4)0.007 (2)
O13a0.287 (3)0.474 (2)0.9253 (4)0.008 (3)
O14a0.50.50.00.021 (7)
O15a0.215 (3)0.192 (2)0.9734 (5)0.008 (3)
O16a0.287 (3)0.137 (2)0.0197 (5)0.007 (3)
O1b0.275 (3)0.028 (2)0.7126 (5)0.015 (3)
O2b0.8090.9820.70740.013
O3b0.4980.6900.73860.013
O4b0.518 (3)0.991 (2)0.6403 (6)0.010 (4)
O5b0.233 (3)0.679 (2)0.6714 (4)0.007 (3)
O6b0.733 (3)0.641 (2)0.6650 (5)0.010 (3)
O7b0.995 (4)0.323 (3)0.6897 (7)0.018 (5)
O8b0.005 (3)0.662 (3)0.5957 (7)0.011 (5)
O9b0.790 (3)0.305 (2)0.6159 (5)0.013 (3)
O10b0.291 (3)0.351 (2)0.6236 (4)0.006 (2)
O11b0.506 (3)0.329 (3)0.5470 (6)0.011 (5)
O12b0.718 (2)0.973 (2)0.5682 (4)0.005 (3)
O13b0.214 (2)0.022 (2)0.5749 (4)0.003 (2)
O14b0.00.00.50.014 (6)
O15b0.787 (3)0.637 (2)0.5219 (5)0.013 (3)
O16b0.286 (3)0.688 (2)0.5288 (4)0.006 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
W1a0.0110 (5)0.0092 (5)0.0051 (5)0.0033 (4)0.0002 (4)0.0019 (4)
W2a0.0141 (5)0.0068 (4)0.0066 (4)0.0016 (4)0.0017 (4)0.0025 (4)
W3a0.0128 (6)0.0100 (5)0.0093 (6)0.0042 (5)0.0037 (5)0.0040 (4)
W4a0.0135 (7)0.0106 (5)0.0088 (7)0.0030 (5)0.0028 (5)0.0046 (5)
W5a0.0126 (8)0.0130 (7)0.0103 (8)0.0040 (6)0.0028 (7)0.0055 (7)
W1b0.0079 (5)0.0067 (4)0.0067 (5)0.0004 (4)0.0029 (4)0.0004 (4)
W2b0.0111 (5)0.0082 (5)0.0096 (5)0.0035 (4)0.0037 (4)0.0044 (4)
W3b0.0144 (6)0.0093 (5)0.0074 (6)0.0030 (5)0.0041 (5)0.0030 (4)
W4b0.0137 (7)0.0124 (6)0.0084 (7)0.0064 (5)0.0048 (5)0.0053 (4)
W5b0.0165 (9)0.0135 (8)0.0045 (7)0.0079 (7)0.0040 (6)0.0058 (6)
Bond lengths (Å) top
W1a—O1a2.05 (1)W1b—O5bii1.79 (1)
W1a—O2ai2.01 (2)W1b—O6b1.82 (1)
W1a—O3a1.97 (3)W2b—O5b2.03 (1)
W1a—O4ai1.82 (2)W2b—O6b1.97 (2)
W1a—O5aii1.83 (1)W2b—O7b1.99 (2)
W1a—O6a1.83 (2)W2b—O8b1.81 (2)
W2a—O5a1.99 (2)W2b—O9bvii1.82 (1)
W2a—O6a1.95 (2)W2b—O10bviii1.81 (2)
W2a—O7a1.99 (2)W3b—O4b1.93 (2)
W2a—O8a1.82 (2)W3b—O9b1.97 (2)
W2a—O9a1.81 (1)W3b—O10b1.99 (1)
W2a—O10aii1.85 (2)W3b—O11bi1.84 (2)
W3a—O4a1.94 (2)W3b—O12b1.83 (1)
W3a—O9a1.96 (2)W3b—O13b1.85 (1)
W3a—O10a1.94 (1)W4b—O8b1.97 (2)
W3a—O11a1.83 (2)W4b—O12b1.92 (1)
W3a—O12a1.87 (1)W4b—O13bix1.94 (1)
W3a—O13a1.81 (2)W4b—O14b1.868 (1)
W4a—O8aiii1.97 (2)W4b—O15bii1.87 (1)
W4a—O12aiv1.91 (1)W4b—O16b1.85 (1)
W4a—O13av1.95 (1)W5b—O11b1.90 (2)
W4a—O14a1.873 (1)W5b—O11bx1.90 (2)
W4a—O15avi1.87 (2)W5b—O15b1.91 (2)
W4a—O16aii1.89 (1)W5b—O15bx1.91 (2)
W5a—O11a1.91 (2)W5b—O16b1.92 (1)
W5a—O11avi1.91 (2)W5b—O16bx1.92 (1)
W5a—O15a1.91 (1)Pa—O1avii1.55 (2)
W5a—O15avi1.91 (1)Pa—O2a1.51 (2)
W5a—O16a1.87 (2)Pa—O7a1.53 (2)
W5a—O16avi1.87 (2)Pa—O3bvii1.50 (1)
W1b—O1bi2.02 (1)Pb—O3aix1.47 (3)
W1b—O2b2.04 (2)Pb—O1b1.57 (2)
W1b—O3b1.97 (1)Pb—O2bvii1.51 (2)
W1b—O4b1.82 (2)Pb—O7b1.52 (2)
Symmetry codes: (i) x1, y+1, z; (ii) x1, y, z; (iii) x+1, y, z+2; (iv) x+1, y1, z+2; (v) x+2, y1, z+2; (vi) x+2, y, z+2; (vii) x, y1, z; (viii) x+1, y1, z; (ix) x+1, y, z; (x) x+3, y+1, z+1.

Experimental details

Crystal data
Chemical formulaO62P4W18
Mr4425.1
Crystal system, space groupTriclinic, P1
Temperature (K)293
a, b, c (Å)5.2945 (9), 6.542 (2), 32.744 (5)
α, β, γ (°)90.00 (2), 90.20 (2), 89.78 (2)
V3)1134.2 (4)
Z1
Radiation typeMo Kα
µ (mm1)45.71
Crystal size (mm)158 × 144 × 4
Data collection
DiffractometerEnraf Nonius CAD4
diffractometer
Absorption correctionGaussian
Tmin, Tmax0.148, 0.833
No. of measured, independent and
observed [I > 3σ(I)] reflections
20410, 20041, 4661
Rint?
(sin θ/λ)max1)0.995
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.057, 0.047, 2.79
No. of reflections4661
No. of parameters200
No. of restraints?
Δρmax, Δρmin (e Å3)1.44, 1.34

Computer programs: CAD4 (Enraf Nonius, 1980), SET4 (Enraf Nonius, 1989).

 

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