research papers
In the framework of expanding the range of copper-based compounds in the pyroxene family, we have synthesized at high pressure and high temperature a powder containing a mixture of a new phase with stoichiometry Sr5CuGe9O24 having two identified impurity phases. Electron crystallography showed that the new phase crystallizes in the monoclinic space group P2/c, with unit-cell parameters a = 11.8 Å, b = 8.1 Å, c = 10.3 Å and β = 101.3°. We applied the recently developed low-dose electron diffraction tomography method to solve the structure by direct methods. The obtained structure model contains all 9 independent cation positions and all 13 oxygen positions. A subsequent refinement against powder X-ray diffraction data ascertained the high quality of the structure solution, in particular, the unusual structural arrangement that there are three different environments for Ge in this phase.
Keywords: electron crystallography; structure determination; high pressure; high temperature; pyroxene.
Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S2052520620008914/je5030sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S2052520620008914/je5030Isup2.hkl |
CCDC reference: 2013451
Computing details top
(I) top
Crystal data top
CuGe9O24·5(Sr) | β = 101.5972 (13)° |
Mr = 1538.9 | V = 984.44 (4) Å3 |
Monoclinic, P2/c | Z = 2 |
Hall symbol: -P 2yc | F(000) = 488 |
a = 11.8817 (3) Å | Dx = 5.192 Mg m−3 |
b = 8.19277 (17) Å | Cu Kα1 radiation |
c = 10.3237 (2) Å | T = 293 K |
Data collection top
Bruker D5000 diffractometer | Ge 111 monochromator |
Radiation source: sealed X-ray tube | 2θmin = 10°, 2θmax = 90.317°, 2θstep = 0.032° |
Refinement top
Rp = 0.028 | 0 restraints |
Rwp = 0.038 | 14 constraints |
Rexp = 0.024 | Weighting scheme based on measured s.u.'s |
R(F) = 0.028 | (Δ/σ)max = 0.024 |
2515 data points | Background function: 19 Legendre polynoms |
Profile function: Pseudo-Voigt | Preferred orientation correction: none |
110 parameters |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
x | y | z | Uiso*/Ueq | ||
Sr1 | 1 | −0.6469 (8) | 0.75 | 0.007 (2)* | |
Sr2 | 0.7559 (4) | 0.0316 (5) | 0.6837 (4) | 0.0047 (16)* | |
Sr3 | 0.6505 (4) | −0.5151 (5) | 0.6817 (5) | 0.0080 (15)* | |
Ge1 | 0.8529 (5) | −0.2890 (6) | 0.9356 (5) | 0.0054 (17)* | |
Ge2 | 0.5889 (4) | 0.1750 (7) | 0.3708 (6) | 0.0119 (19)* | |
Ge3 | 0.7896 (5) | −0.3288 (7) | 0.4766 (5) | 0.0072 (16)* | |
Ge4 | 0.5412 (4) | −0.1599 (7) | 0.4122 (6) | 0.0095 (18)* | |
Ge5 | 1 | −0.2199 (9) | 0.75 | 0.008 (2)* | |
Cu1 | 1 | 0 | 1 | 0.006 (3)* | |
O1 | 0.797 (2) | −0.305 (3) | 0.315 (3) | 0.011 (2)* | |
O2 | 0.544 (2) | −0.036 (3) | 0.630 (3) | 0.011 (2)* | |
O3 | 0.944 (2) | −0.407 (3) | 0.827 (3) | 0.011 (2)* | |
O4 | 0.647 (2) | −0.325 (3) | 0.489 (3) | 0.011 (2)* | |
O5 | 0.415 (2) | −0.264 (3) | 0.469 (3) | 0.011 (2)* | |
O6 | 0.671 (2) | −0.023 (3) | 0.421 (3) | 0.011 (2)* | |
O7 | 0.5 | 0.344 (5) | 0.25 | 0.011 (2)* | |
O8 | 0.909 (2) | −0.182 (3) | 1.065 (3) | 0.011 (2)* | |
O9 | 0.869 (2) | −0.216 (3) | 0.595 (3) | 0.011 (2)* | |
O10 | 0.716 (2) | −0.276 (3) | 0.836 (3) | 0.011 (2)* | |
O11 | 0.817 (2) | −0.473 (3) | 1.026 (2) | 0.011 (2)* | |
O12 | 0.5 | −0.260 (4) | 0.25 | 0.011 (2)* | |
O13 | 0.909 (2) | −0.079 (3) | 0.820 (3) | 0.011 (2)* |
Geometric parameters (Å, º) top
Sr1—O1i | 2.66 (3) | Ge2—O2vii | 1.95 (3) |
Sr1—O1ii | 2.66 (3) | Ge2—O2viii | 2.69 (3) |
Sr1—O3 | 2.28 (2) | Ge2—O5vii | 1.82 (3) |
Sr1—O3iii | 2.28 (2) | Ge2—O6 | 1.91 (3) |
Sr1—O8iv | 2.44 (3) | Ge2—O7 | 2.02 (3) |
Sr1—O8v | 2.44 (3) | Ge2—O10viii | 1.83 (3) |
Sr1—O11iv | 3.01 (2) | Ge3—O1 | 1.70 (3) |
Sr1—O11v | 3.01 (2) | Ge3—O4 | 1.73 (3) |
Sr2—O1vi | 2.61 (3) | Ge3—O6 | 2.87 (3) |
Sr2—O2 | 2.52 (3) | Ge3—O9 | 1.67 (3) |
Sr2—O5vii | 2.99 (2) | Ge3—O11v | 1.71 (3) |
Sr2—O6 | 2.74 (3) | Ge4—O2 | 2.46 (3) |
Sr2—O6vi | 2.83 (3) | Ge4—O2vii | 1.90 (3) |
Sr2—O8viii | 2.69 (3) | Ge4—O4 | 1.90 (3) |
Sr2—O9 | 2.69 (3) | Ge4—O5 | 1.92 (3) |
Sr2—O10 | 3.06 (3) | Ge4—O6 | 1.89 (3) |
Sr2—O13 | 2.25 (2) | Ge4—O12 | 1.841 (17) |
Sr3—O1ii | 2.47 (2) | Ge5—O3 | 1.91 (3) |
Sr3—O4 | 2.52 (3) | Ge5—O3iii | 1.91 (3) |
Sr3—O5ix | 2.41 (3) | Ge5—O9 | 1.99 (2) |
Sr3—O7vii | 2.48 (2) | Ge5—O9iii | 1.99 (2) |
Sr3—O10 | 2.54 (3) | Ge5—O13 | 1.83 (3) |
Sr3—O11v | 2.79 (3) | Ge5—O13iii | 1.83 (3) |
Sr3—O12ix | 2.76 (2) | Cu1—O8 | 2.03 (3) |
Ge1—O3 | 1.96 (3) | Cu1—O8x | 2.03 (3) |
Ge1—O8 | 1.62 (3) | Cu1—O9iii | 2.67 (3) |
Ge1—O10 | 1.74 (3) | Cu1—O9vi | 2.67 (3) |
Ge1—O11 | 1.87 (3) | Cu1—O13 | 2.05 (2) |
Ge1—O13 | 2.27 (3) | Cu1—O13x | 2.05 (2) |
O1i—Sr1—O1ii | 163.0 (8) | O10—Sr3—O12ix | 119.2 (8) |
O1i—Sr1—O3 | 124.2 (9) | O11v—Sr3—O12ix | 134.2 (8) |
O1i—Sr1—O3iii | 72.2 (9) | O3—Ge1—O8 | 123.4 (12) |
O1i—Sr1—O8iv | 80.3 (9) | O3—Ge1—O10 | 104.2 (13) |
O1i—Sr1—O8v | 89.9 (9) | O3—Ge1—O11 | 95.5 (11) |
O1i—Sr1—O11iv | 71.8 (8) | O3—Ge1—O13 | 79.7 (10) |
O1i—Sr1—O11v | 114.2 (8) | O8—Ge1—O10 | 129.6 (13) |
O1ii—Sr1—O3 | 72.2 (9) | O8—Ge1—O11 | 97.1 (13) |
O1ii—Sr1—O3iii | 124.2 (9) | O8—Ge1—O13 | 84.6 (12) |
O1ii—Sr1—O8iv | 89.9 (9) | O10—Ge1—O11 | 93.6 (11) |
O1ii—Sr1—O8v | 80.3 (9) | O10—Ge1—O13 | 88.9 (11) |
O1ii—Sr1—O11iv | 114.2 (8) | O11—Ge1—O13 | 175.0 (11) |
O1ii—Sr1—O11v | 71.8 (8) | O2vii—Ge2—O2viii | 75.0 (10) |
O3—Sr1—O3iii | 60.2 (10) | O2vii—Ge2—O5vii | 93.9 (12) |
O3—Sr1—O8iv | 109.7 (9) | O2vii—Ge2—O6 | 82.7 (11) |
O3—Sr1—O8v | 131.1 (9) | O2vii—Ge2—O7 | 94.3 (9) |
O3—Sr1—O11iv | 70.4 (8) | O2vii—Ge2—O10viii | 166.0 (12) |
O3—Sr1—O11v | 76.6 (8) | O2viii—Ge2—O5vii | 167.4 (10) |
O3iii—Sr1—O8iv | 131.1 (9) | O2viii—Ge2—O6 | 83.4 (10) |
O3iii—Sr1—O8v | 109.7 (9) | O2viii—Ge2—O7 | 74.8 (9) |
O3iii—Sr1—O11iv | 76.6 (8) | O2viii—Ge2—O10viii | 91.4 (11) |
O3iii—Sr1—O11v | 70.4 (8) | O5vii—Ge2—O6 | 101.6 (12) |
O8iv—Sr1—O8v | 109.9 (9) | O5vii—Ge2—O7 | 100.4 (10) |
O8iv—Sr1—O11iv | 56.5 (8) | O5vii—Ge2—O10viii | 99.9 (12) |
O8iv—Sr1—O11v | 158.2 (8) | O6—Ge2—O7 | 157.9 (11) |
O8v—Sr1—O11iv | 158.2 (8) | O6—Ge2—O10viii | 92.4 (11) |
O8v—Sr1—O11v | 56.5 (8) | O7—Ge2—O10viii | 85.2 (9) |
O11iv—Sr1—O11v | 141.7 (8) | O1—Ge3—O4 | 108.1 (13) |
O1vi—Sr2—O2 | 112.0 (8) | O1—Ge3—O6 | 79.8 (10) |
O1vi—Sr2—O5vii | 76.2 (7) | O1—Ge3—O9 | 121.9 (13) |
O1vi—Sr2—O6 | 130.4 (8) | O1—Ge3—O11v | 111.0 (12) |
O1vi—Sr2—O6vi | 68.5 (8) | O4—Ge3—O6 | 63.2 (11) |
O1vi—Sr2—O8viii | 76.7 (9) | O4—Ge3—O9 | 110.9 (14) |
O1vi—Sr2—O9 | 140.2 (8) | O4—Ge3—O11v | 97.1 (12) |
O1vi—Sr2—O10 | 118.3 (8) | O6—Ge3—O9 | 81.4 (10) |
O1vi—Sr2—O13 | 88.7 (8) | O6—Ge3—O11v | 160.0 (10) |
O2—Sr2—O5vii | 59.0 (8) | O9—Ge3—O11v | 105.0 (12) |
O2—Sr2—O6 | 65.9 (8) | O2—Ge4—O2vii | 76.7 (10) |
O2—Sr2—O6vi | 70.8 (8) | O2—Ge4—O4 | 91.5 (10) |
O2—Sr2—O8viii | 137.4 (8) | O2—Ge4—O5 | 77.0 (10) |
O2—Sr2—O9 | 107.6 (8) | O2—Ge4—O6 | 81.5 (11) |
O2—Sr2—O10 | 71.5 (7) | O2—Ge4—O12 | 165.4 (7) |
O2—Sr2—O13 | 133.8 (9) | O2vii—Ge4—O4 | 166.1 (11) |
O5vii—Sr2—O6 | 60.4 (8) | O2vii—Ge4—O5 | 91.8 (11) |
O5vii—Sr2—O6vi | 98.4 (8) | O2vii—Ge4—O6 | 84.4 (11) |
O5vii—Sr2—O8viii | 85.3 (8) | O2vii—Ge4—O12 | 97.9 (12) |
O5vii—Sr2—O9 | 129.4 (8) | O4—Ge4—O5 | 92.7 (11) |
O5vii—Sr2—O10 | 129.7 (7) | O4—Ge4—O6 | 86.6 (11) |
O5vii—Sr2—O13 | 164.0 (8) | O4—Ge4—O12 | 95.3 (12) |
O6—Sr2—O6vi | 136.7 (7) | O5—Ge4—O6 | 158.4 (12) |
O6—Sr2—O8viii | 76.9 (8) | O5—Ge4—O12 | 89.8 (10) |
O6—Sr2—O9 | 69.6 (8) | O6—Ge4—O12 | 111.8 (10) |
O6—Sr2—O10 | 108.0 (8) | O3—Ge5—O3iii | 73.4 (12) |
O6—Sr2—O13 | 130.2 (9) | O3—Ge5—O9 | 93.7 (11) |
O6vi—Sr2—O8viii | 142.8 (8) | O3—Ge5—O9iii | 87.7 (11) |
O6vi—Sr2—O9 | 124.3 (8) | O3—Ge5—O13 | 93.2 (12) |
O6vi—Sr2—O10 | 54.4 (8) | O3—Ge5—O13iii | 163.3 (11) |
O6vi—Sr2—O13 | 80.4 (9) | O3iii—Ge5—O9 | 87.7 (11) |
O8viii—Sr2—O9 | 76.2 (8) | O3iii—Ge5—O9iii | 93.7 (11) |
O8viii—Sr2—O10 | 143.1 (8) | O3iii—Ge5—O13 | 163.3 (11) |
O8viii—Sr2—O13 | 86.1 (9) | O3iii—Ge5—O13iii | 93.2 (12) |
O9—Sr2—O10 | 71.9 (8) | O9—Ge5—O9iii | 178.3 (11) |
O9—Sr2—O13 | 61.0 (9) | O9—Ge5—O13 | 83.1 (11) |
O10—Sr2—O13 | 62.4 (8) | O9—Ge5—O13iii | 95.8 (11) |
O1ii—Sr3—O4 | 135.0 (9) | O9iii—Ge5—O13 | 95.8 (11) |
O1ii—Sr3—O5ix | 90.6 (8) | O9iii—Ge5—O13iii | 83.1 (11) |
O1ii—Sr3—O7vii | 130.0 (8) | O13—Ge5—O13iii | 101.5 (12) |
O1ii—Sr3—O10 | 91.0 (8) | O8—Cu1—O8x | 180 |
O1ii—Sr3—O11v | 78.5 (9) | O8—Cu1—O9iii | 91.1 (10) |
O1ii—Sr3—O12ix | 83.0 (7) | O8—Cu1—O9vi | 88.9 (10) |
O4—Sr3—O5ix | 90.1 (9) | O8—Cu1—O13 | 81.4 (10) |
O4—Sr3—O7vii | 88.7 (8) | O8—Cu1—O13x | 98.6 (10) |
O4—Sr3—O10 | 88.5 (9) | O8x—Cu1—O9iii | 88.9 (10) |
O4—Sr3—O11v | 57.9 (8) | O8x—Cu1—O9vi | 91.1 (10) |
O4—Sr3—O12ix | 134.8 (6) | O8x—Cu1—O13 | 98.6 (10) |
O5ix—Sr3—O7vii | 116.7 (8) | O8x—Cu1—O13x | 81.4 (10) |
O5ix—Sr3—O10 | 178.4 (9) | O9iii—Cu1—O9vi | 180 |
O5ix—Sr3—O11v | 77.1 (9) | O9iii—Cu1—O13 | 72.5 (9) |
O5ix—Sr3—O12ix | 61.4 (8) | O9iii—Cu1—O13x | 107.5 (9) |
O7vii—Sr3—O10 | 62.5 (8) | O9vi—Cu1—O13 | 107.5 (9) |
O7vii—Sr3—O11v | 144.8 (9) | O9vi—Cu1—O13x | 72.5 (9) |
O7vii—Sr3—O12ix | 76.2 (9) | O13—Cu1—O13x | 180 |
O10—Sr3—O11v | 102.8 (9) |
Symmetry codes: (i) −x+2, −y−1, −z+1; (ii) x, −y−1, z+1/2; (iii) −x+2, y, −z+3/2; (iv) −x+2, −y−1, −z+2; (v) x, −y−1, z−1/2; (vi) x, −y, z+1/2; (vii) −x+1, −y, −z+1; (viii) x, −y, z−1/2; (ix) −x+1, −y−1, −z+1; (x) −x+2, −y, −z+2. |