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The binary phase diagram of Cu–Si is unexpectedly complex in the vicinity of Cu3+xSi. The low-temperature region contains three closely related incommensurately modulated phases denoted, in order of increasing temperature of stability, η′′′, η′′ and η′. The structure analysis of η′ has been reported previously [Palatinus et al. (2011). Inorg. Chem. 50, 3743]. Here the structure model for the phases η′′ and η′′′ is reported. The structures could be solved in superspace, but no superspace structure model could be constructed due to the complexity of the modulation functions. Therefore, the structures were described in a supercell approximation, which involved a 4 × 4 × 3 supercell for the η′′ phase and a 14 × 14 × 3 supercell for the η′′′ phase. Both structures are very similar and differ only by a subtle symmetry lowering from η′′ to η′′′. A comparison of the structure models of η′′ and η′′′ with the reported structure of η′ suggests that the reported structure model of η′ contains an incorrect assignment of atomic types.
Supporting information
CCDC references: 1545784; 1545785
For both structures, data collection: Bruker SAINT, v. 8.34A; cell refinement: Bruker SAINT, v. 8.34A; data reduction: Bruker SAINT, v. 8.34A, SADABS (Sheldrick 1996); program(s) used to solve structure: Supeflip (Palatinus and Chapuis, 2007); program(s) used to refine structure: Jana2006 (Petricek et al., 2014).
Crystal data top
Cu3.313Si | Dx = 7.563 Mg m−3 |
Mr = 238.6 | Mo Kα radiation, λ = 0.71073 Å |
Trigonal, P31c | Cell parameters from 1361 reflections |
Hall symbol: -P 3;-2c | θ = 5.6–28.9° |
a = 16.2448 (4) Å | µ = 33.35 mm−1 |
c = 44.017 (8) Å | T = 743 K |
V = 10060 (2) Å3 | Irregular, metallic gray |
Z = 192 | 0.16 × 0.13 × 0.09 mm |
F(000) = 21132 | |
Data collection top
KappaCCD (Bruker-Nonius) diffractometer | 624 reflections with I > 3σ(I) |
Graphite monochromator | Rint = 0.240 |
phi–scan | θmax = 30.4°, θmin = 2.7° |
Absorption correction: multi-scan SADABS (J.Appl.Cryst.48 (2015). ) | h = −23→22 |
Tmin = 0.420, Tmax = 0.746 | k = −23→23 |
25292 measured reflections | l = −62→61 |
4996 independent reflections | |
Refinement top
Refinement on F | 0 restraints |
R[F2 > 2σ(F2)] = 0.150 | 282 constraints |
wR(F2) = 0.159 | Weighting scheme based on measured s.u.'s w = 1/(σ2(F) + 0.0001F2) |
S = 2.35 | (Δ/σ)max = 0.003 |
4996 reflections | Δρmax = 13.76 e Å−3 |
6 parameters | Δρmin = −14.71 e Å−3 |
Special details top
Refinement. In reality incommensurately modulated structure.
Model obtained by solution of a large supercell. Coordinates fixed to values
from solution, isotropic displacement parameters refined, but fixed to be
constant in each crystallographicaly independent layer. Reflections limited
only to main reflections and satellites of the incommensurate structure. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
Cu02001 | 0.330488 | 0.420553 | 0.021641 | 0.0264 (4)* | |
Cu02002 | 0.350199 | 0.147312 | 0.024788 | 0.0264 (4)* | |
Cu02003 | 0.670782 | 0.090332 | 0.023323 | 0.0264 (4)* | |
Cu02004 | 0.829669 | 0.916623 | 0.024926 | 0.0264 (4)* | |
Cu02005 | 0.552851 | 0.152952 | 0.02612 | 0.0264 (4)* | |
Cu02006 | 0.333333 | 0.666667 | 0.024115 | 0.0264 (4)* | |
Cu02007 | 0.148419 | 0.355504 | 0.027323 | 0.0264 (4)* | |
Cu02008 | 0.376704 | 0.004008 | 0.027971 | 0.0264 (4)* | |
Cu02009 | 0.15083 | 0.551475 | 0.029966 | 0.0264 (4)* | |
Cu02010 | 0.908029 | 0.081561 | 0.03121 | 0.0264 (4)* | |
Cu02011 | 0.666667 | 0.333333 | 0.030443 | 0.0264 (4)* | |
Cu03001 | 0 | 0 | 0.053569 | 0.0190 (3)* | |
Cu03002 | 0.252709 | 0.259815 | 0.054954 | 0.0190 (3)* | |
Cu03003 | 0.503812 | 0.258787 | 0.055481 | 0.0190 (3)* | |
Cu03004 | 0.266695 | 0.510891 | 0.054993 | 0.0190 (3)* | |
Cu03005 | 0.510899 | 0.002051 | 0.055946 | 0.0190 (3)* | |
Cu03006 | 0.242529 | 1.000112 | 0.056445 | 0.0190 (3)* | |
Cu04001 | 0.085396 | 0.419295 | 0.0794 | 0.0184 (4)* | |
Cu04002 | 0.329906 | 0.16564 | 0.082023 | 0.0184 (4)* | |
Cu04003 | 0.332862 | 0.418198 | 0.083294 | 0.0184 (4)* | |
Cu04004 | 0.086941 | 0.169049 | 0.085457 | 0.0184 (4)* | |
Cu04005 | 0.580291 | 0.165754 | 0.084993 | 0.0184 (4)* | |
Cu04006 | 0.333333 | 0.666667 | 0.087867 | 0.0184 (4)* | |
Cu05001 | 0 | 0 | 0.110209 | 0.0190 (3)* | |
Cu05002 | 0.242312 | 0.487496 | 0.110366 | 0.0190 (3)* | |
Cu05003 | 0.753774 | 0.243312 | 0.110687 | 0.0190 (3)* | |
Cu05004 | 0.741411 | 0.003101 | 0.111305 | 0.0190 (3)* | |
Cu05005 | 0.492342 | 0.499552 | 0.111525 | 0.0190 (3)* | |
Cu05006 | 0.26031 | 1.000511 | 0.112133 | 0.0190 (3)* | |
Cu06001 | 0.431454 | 0.088662 | 0.135467 | 0.0264 (4)* | |
Cu06002 | 0.215952 | 0.609382 | 0.13746 | 0.0264 (4)* | |
Cu06003 | 0.155029 | 0.312704 | 0.139101 | 0.0264 (4)* | |
Cu06004 | 0.610446 | 0.217592 | 0.140302 | 0.0264 (4)* | |
Cu06005 | 0.089034 | 0.42884 | 0.141128 | 0.0264 (4)* | |
Cu06006 | 0.319242 | 0.156851 | 0.142699 | 0.0264 (4)* | |
Cu06007 | 0.663512 | 0.089342 | 0.142678 | 0.0264 (4)* | |
Cu06008 | 0.335895 | 0.428034 | 0.144527 | 0.0264 (4)* | |
Cu08001 | 0.666667 | 0.333333 | 0.189642 | 0.0264 (4)* | |
Cu08002 | 0.180621 | 0.085933 | 0.189741 | 0.0264 (4)* | |
Cu08003 | 0.333333 | 0.666667 | 0.190937 | 0.0264 (4)* | |
Cu08004 | 0.410102 | 0.561712 | 0.189282 | 0.0264 (4)* | |
Cu08005 | 0.082127 | 0.172119 | 0.190433 | 0.0264 (4)* | |
Cu08006 | 0.414749 | 0.087143 | 0.192505 | 0.0264 (4)* | |
Cu08007 | 0.209613 | 0.357023 | 0.19302 | 0.0264 (4)* | |
Cu08008 | 0.596519 | 0.150357 | 0.193481 | 0.0264 (4)* | |
Cu08009 | 0.619849 | 0.996459 | 0.194364 | 0.0264 (4)* | |
Cu08010 | 0.791224 | 0.145781 | 0.196653 | 0.0264 (4)* | |
Cu08011 | 0.091353 | 0.4131 | 0.1986 | 0.0264 (4)* | |
Cu09001 | 0.252089 | 0.005236 | 0.220901 | 0.0190 (3)* | |
Cu09002 | 0 | 0 | 0.221725 | 0.0190 (3)* | |
Cu09003 | 0.508636 | 0.245179 | 0.222373 | 0.0190 (3)* | |
Cu09004 | 0.251688 | 0.509733 | 0.222295 | 0.0190 (3)* | |
Cu09005 | 0.487196 | −0.000996 | 0.222368 | 0.0190 (3)* | |
Cu09006 | 0.755764 | −0.002912 | 0.222933 | 0.0190 (3)* | |
Cu10001 | 0.162238 | 0.081119 | 0.25 | 0.0184 (4)* | |
Cu10002 | 0.166464 | 0.583232 | 0.25 | 0.0184 (4)* | |
Cu10003 | 0.666667 | 0.333333 | 0.25 | 0.0184 (4)* | |
Cu10004 | 0.167464 | 0.334928 | 0.25 | 0.0184 (4)* | |
Cu10005 | 0.415734 | 0.084171 | 0.253736 | 0.0184 (4)* | |
Si01001 | 0.247476 | 0.999989 | 0.999102 | 0.034 (9)* | |
Si01002 | 0.741725 | 0.250617 | 0.999076 | 0.034 (9)* | |
Si01003 | 0.5 | 0 | 0 | 0.034 (9)* | |
Si01004 | 0 | 0 | 0 | 0.034 (9)* | |
Si04001 | 0.417857 | 0.081404 | 0.078661 | 0.007 (3)* | |
Si04002 | 0.162522 | 0.331268 | 0.081425 | 0.007 (3)* | |
Si04003 | 0.670239 | 0.083253 | 0.084013 | 0.007 (3)* | |
Si04004 | 0.918313 | 0.081666 | 0.084644 | 0.007 (3)* | |
Si04005 | 0.167356 | 0.584488 | 0.085588 | 0.007 (3)* | |
Si04006 | 0.666667 | 0.333333 | 0.089863 | 0.007 (3)* | |
Si07001 | 0.75241 | 1.001434 | 0.166893 | 0.007 (3)* | |
Si07002 | 0.495708 | 0.00157 | 0.165441 | 0.007 (3)* | |
Si07003 | 0.253651 | 1.992831 | 0.167731 | 0.007 (3)* | |
Si07004 | 0.247227 | 0.499751 | 0.167169 | 0.007 (3)* | |
Si07005 | 0.494207 | 0.243647 | 0.165664 | 0.007 (3)* | |
Si07006 | 0 | 0 | 0.168619 | 0.007 (3)* | |
Si10001 | 0.582914 | 0.165828 | 0.25 | 0.034 (9)* | |
Si10002 | 0.08296 | 0.16592 | 0.25 | 0.034 (9)* | |
Si10003 | 0.333333 | 0.666667 | 0.25 | 0.034 (9)* | |
Si10004 | 0.332432 | 0.166216 | 0.25 | 0.034 (9)* | |
Si10005 | 0.081915 | 0.416604 | 0.254474 | 0.034 (9)* | |
Cur1a | 0.004825 | −0.127275 | 0.135 | 0.0264 (4)* | 0.1667 |
Cur1/1a | 0.143912 | 0.035854 | 0.135 | 0.0264 (4)* | 0.1667 |
Cur1/2a | 0.084117 | 0.149434 | 0.135 | 0.0264 (4)* | 0.1667 |
Cur1/3a | −0.091925 | 0.056501 | 0.135 | 0.0264 (4)* | 0.1667 |
Cur1/4a | −0.14093 | −0.114515 | 0.135 | 0.0264 (4)* | 0.1667 |
Cur1b | −0.004825 | 0.127275 | 0.135 | 0.0264 (4)* | 0.1667 |
Cur1/1b | −0.143912 | −0.035854 | 0.135 | 0.0264 (4)* | 0.1667 |
Cur1/2b | −0.084117 | −0.149434 | 0.135 | 0.0264 (4)* | 0.1667 |
Cur1/3b | 0.091925 | −0.056501 | 0.135 | 0.0264 (4)* | 0.1667 |
Cur1/4b | 0.14093 | 0.114515 | 0.135 | 0.0264 (4)* | 0.1667 |
Crystal data top
Cu3.311Si | Dx = 7.519 Mg m−3 |
Mr = 238.5 | Mo Kα radiation, λ = 0.71073 Å |
Trigonal, P3 | Cell parameters from 2251 reflections |
Hall symbol: -P 3 | θ = 5.6–28.2° |
a = 56.9800 (3) Å | µ = 33.35 mm−1 |
c = 44.055 (2) Å | T = 393 K |
V = 123870 (6) Å3 | Irregular, metallic gray |
Z = 2352 | 0.16 × 0.13 × 0.09 mm |
F(000) = 258780 | |
Data collection top
KappaCCD (Bruker-Nonius) diffractometer | 1471 reflections with I > 3σ(I) |
Graphite monochromator | Rint = 0.139 |
phi–scan | θmax = 29.3°, θmin = 2.0° |
Absorption correction: multi-scan SADABS (J.Appl.Cryst.48 (2015). ) | h = −77→77 |
Tmin = 0.420, Tmax = 0.746 | k = −77→77 |
25518 measured reflections | l = −60→59 |
4920 independent reflections | |
Refinement top
Refinement on F | 0 restraints |
R[F2 > 2σ(F2)] = 0.119 | 6777 constraints |
wR(F2) = 0.137 | Weighting scheme based on measured s.u.'s w = 1/(σ2(F) + 0.0001F2) |
S = 2.93 | (Δ/σ)max = 0.001 |
4920 reflections | Δρmax = 12.91 e Å−3 |
6 parameters | Δρmin = −17.54 e Å−3 |
Special details top
Refinement. In reality incommensurately modulated structure.
Model obtained by solution of a large supercell. Coordinates fixed to values
from solution, isotropic displacement parameters refined, but fixed to be
constant in each crystallographicaly independent layer. Reflections limited
only to main reflections and satellites of the incommensurate structure. |
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