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The crystal structure of pyrochlore-related NaCdZn2F7 (sodium cadmium dizinc heptafluoride) has been determined via synchrotron diffraction. Zn is octahedrally coordinated by fluorine. Na and Cd are both coordinated by eight anions. Despite the different chemical characteristics and valences, no indication of ordering of Na and Cd was observed.
Supporting information
Key indicators
- Single-crystal synchrotron study
- T = 293 K
- Mean (Wave) = 0.000 Å
- R factor = 0.032
- wR factor = 0.039
- Data-to-parameter ratio = 36.7
checkCIF/PLATON results
No syntax errors found
Alert level C
CELLV02_ALERT_1_C The supplied cell volume s.u. differs from that
calculated from the cell parameter s.u.'s by > 2
Calculated cell volume su = 5.56
Cell volume su given = 3.00
DIFMX01_ALERT_2_C The maximum difference density is > 0.1*ZMAX*0.75
_refine_diff_density_max given = 3.970
Test value = 3.600
DIFMX02_ALERT_1_C The minimum difference density is > 0.1*ZMAX*0.75
The relevant atom site should be identified.
GOODF01_ALERT_2_C The least squares goodness of fit parameter lies
outside the range 0.80 <> 2.00
Goodness of fit given = 2.300
Alert level G
ABSMU_01 Radiation type not identified. Calculation of
_exptl_absorpt_correction_mu not performed.
ABSTM02_ALERT_3_G The ratio of expected to reported Tmax/Tmin(RR') is < 0.90
Tmin and Tmax reported: 0.265 0.497
Tmin' and Tmax expected: 0.586 0.903
RR' = 0.822
Please check that your absorption correction is appropriate.
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
correct. If it is not, please give the correct count in the
_publ_section_exptl_refinement section of the submitted CIF.
From the CIF: _diffrn_reflns_theta_max 31.80
From the CIF: _reflns_number_total 404
Count of symmetry unique reflns 0
Completeness (_total/calc) +++++++++++++%
TEST3: Check Friedels for noncentro structure
Estimate of Friedel pairs measured 404
Fraction of Friedel pairs measured++++++++++
Are heavy atom types Z>Si present yes
0 ALERT level A = In general: serious problem
0 ALERT level B = Potentially serious problem
4 ALERT level C = Check and explain
2 ALERT level G = General alerts; check
2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
2 ALERT type 2 Indicator that the structure model may be wrong or deficient
1 ALERT type 3 Indicator that the structure quality may be low
1 ALERT type 4 Improvement, methodology, query or suggestion
Data collection: DIF4 (Eichhorn & Lippmann, 2001); cell refinement: LeBail fit of synchrotron powder data (JANA2000; Petřiček & Dušek,
2000); data reduction: REDUCE (Eichhorn, 1995) and AVSORT (Eichhorn, 1992); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: JANA2000; molecular graphics: ATOMS (Dowty, 1999); software used to prepare material for publication: JANA2000'.
sodium cadmium dizinc heptafluoride
top
Crystal data top
NaCdZn2F7 | Dx = 4.786 Mg m−3 |
Mr = 399.13 | Synchrotron radiation, λ = 0.45 Å |
Cubic, Fd3m | Cell parameters from 67 reflections |
Hall symbol: -F 4vw 2vw 3 | θ = 3–35.0° |
a = 10.34657 (3) Å | µ = 8.90 mm−1 |
V = 1107.62 (1) Å3 | T = 293 K |
Z = 8 | Irregular, colourless |
F(000) = 1456 | 0.06 × 0.04 × 0.01 mm |
LeBail fit of powder data | |
Data collection top
Beamline D3 four-circle diffractometer | 324 reflections with I > 3σ(I) |
Radiation source: Hasylab, Hamburg, Germany | Rint = 0.054 |
Double crystal Si (111) monochromator | θmax = 31.8°, θmin = 1.5° |
ω scans | h = −7→24 |
Absorption correction: numerical (JANA2000; Petřiček & Dušek, 2000) | k = −24→24 |
Tmin = 0.265, Tmax = 0.497 | l = −24→23 |
8160 measured reflections | 2 standard reflections every 45 min min |
404 independent reflections | intensity decay: none |
Refinement top
Refinement on F | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F > 3σ(F)] = 0.032 | w = 1/[σ2(Fo) + (0.01Fo)2] |
wR(F) = 0.039 | (Δ/σ)max = −0.014 |
S = 2.30 | Δρmax = 3.97 e Å−3 |
404 reflections | Δρmin = −1.18 e Å−3 |
11 parameters | Extinction correction: Gaussian Type I (Becker & Coppens, 1974) |
3 restraints | Extinction coefficient: 0.21 (2) |
Special details top
Refinement. We therefore give the results based on these data. For the refinement, an
instability factor of 0.01 was used. This instrument-dependent value was
extrapolated on the basis of the fluctuations of the integrated intensities of
the two standard reflections and their corresponding standard deviations. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
Na | 0 | 0 | 0 | 0.01952 (5) | 0.5 |
Cd | 0 | 0 | 0 | 0.01952 (5) | 0.5 |
Zn | 0.5 | 0.5 | 0.5 | 0.01159 (3) | |
F1 | 0.125 | 0.125 | 0.125 | 0.0198 (2) | |
F2 | 0.125 | 0.125 | 0.41728 (12) | 0.0267 (2) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Na | 0.01952 (8) | 0.01952 (8) | 0.01952 (8) | −0.00344 (5) | −0.00344 (5) | −0.00344 (5) |
Cd | 0.01952 (8) | 0.01952 (8) | 0.01952 (8) | −0.00368 (7) | −0.00368 (7) | −0.00368 (7) |
Zn | 0.01159 (7) | 0.01159 (7) | 0.01159 (7) | −0.00036 (3) | −0.00036 (3) | −0.00036 (3) |
F1 | 0.0198 (4) | 0.0198 (4) | 0.0198 (4) | 0 | 0 | 0 |
F2 | 0.0250 (3) | 0.0250 (3) | 0.0302 (6) | −0.0131 (4) | 0 | 0 |
Geometric parameters (Å, º) top
Na—F1 | 2.2401 | Cd—Naii | 3.6581 |
Na—F1i | 2.2401 | Cd—Naix | 3.6581 |
Na—F2ii | 2.5176 (9) | Zn—F2x | 2.0197 (5) |
Na—F2iii | 2.5176 (9) | Zn—F2xi | 2.0197 (5) |
Na—F2iv | 2.5176 (9) | Zn—F2xii | 2.0197 (5) |
Na—F2v | 2.5176 (9) | Zn—F2xiii | 2.0197 (5) |
Na—F2vi | 2.5176 (9) | Zn—F2xiv | 2.0197 (5) |
Na—F2vii | 2.5176 (9) | Zn—F2xv | 2.0197 (5) |
Na—Naviii | 3.6581 | Zn—Naxvi | 3.6581 |
Na—Cdviii | 3.6581 | Zn—Naxvii | 3.6581 |
Na—Cdii | 3.6581 | Zn—Naxviii | 3.6581 |
Na—Cdix | 3.6581 | F1—F2ii | 3.0233 (13) |
Cd—F1 | 2.2401 | F2—F2xix | 3.0406 (13) |
Cd—F1i | 2.2401 | F2—F2xx | 2.6593 (3) |
Cd—F2ii | 2.5176 (9) | F2—F2xxi | 2.6593 (3) |
Cd—F2iii | 2.5176 (9) | F2—F2xxii | 3.0406 (13) |
Cd—F2iv | 2.5176 (9) | F2—F2xxiii | 3.0406 (13) |
Cd—F2v | 2.5176 (9) | F2—F2xxiv | 2.6593 (3) |
Cd—F2vi | 2.5176 (9) | F2—F2xxv | 2.6593 (3) |
Cd—F2vii | 2.5176 (9) | F2—F2 | 3.0406 (13) |
Cd—Naviii | 3.6581 | | |
| | | |
F1—Na—F1i | 180.0 | F2iii—Cd—F2v | 116.25 (1) |
F1—Na—F2iii | 78.67 (2) | F2iii—Cd—F2vi | 116.25 (1) |
F1—Na—F2ii | 101.33 (2) | F2iii—Cd—F2vii | 63.75 (1) |
F1—Na—F2iv | 101.33 (2) | F1i—Cd—F2vii | 78.67 (2) |
F1—Na—F2v | 78.67 (2) | F2x—Zn—F2xi | 180.0 |
F2ii—Na—F2iii | 180.0 | F2x—Zn—F2xiii | 82.35 (3) |
F1—Na—F2vii | 101.33 (2) | F2x—Zn—F2xii | 97.65 (3) |
F1—Na—F2vi | 78.67 (2) | F2x—Zn—F2xv | 97.65 (3) |
F2ii—Na—F2v | 63.75 (1) | F2x—Zn—F2xiv | 82.35 (3) |
F2ii—Na—F2iv | 116.25 (1) | F2xi—Zn—F2xiii | 97.65 (3) |
F1i—Na—F2ii | 78.67 (2) | F2xi—Zn—F2xii | 82.35 (3) |
F1i—Na—F2iii | 101.33 (2) | F2xi—Zn—F2xv | 82.35 (3) |
F2ii—Na—F2vi | 63.75 (1) | F2xi—Zn—F2xiv | 97.65 (3) |
F2iii—Na—F2ii | 180.0 | F2xii—Zn—F2xiv | 82.35 (3) |
F1i—Na—F2v | 101.33 (2) | F2xii—Zn—F2xv | 97.65 (3) |
F1i—Na—F2iv | 78.67 (2) | F2xii—Zn—F2xiii | 180.0 |
F2iii—Na—F2iv | 63.75 (1) | Cd—F1—Cdviii | 109.471 |
F2iii—Na—F2v | 116.25 (1) | Na—F1—Naviii | 109.471 |
F2iii—Na—F2vi | 116.25 (1) | Na—F1—Naix | 109.471 |
F2iii—Na—F2vii | 63.75 (1) | Cd—F1—Cdix | 109.471 |
F1i—Na—F2vii | 78.67 (2) | Na—F1—Naxxvi | 109.471 |
F1—Na—F1i | 180.0 | Cd—F1—Cdxxvi | 109.471 |
F1—Cd—F2iii | 78.67 (2) | Naviii—F1—Naix | 109.471 |
F1—Cd—F2ii | 101.33 (2) | Cdviii—F1—Cdix | 109.471 |
F1—Cd—F2iv | 101.33 (2) | Naviii—F1—Naxxvi | 109.471 |
F1—Cd—F2v | 78.67 (2) | Cdviii—F1—Cdxxvi | 109.471 |
F2ii—Cd—F2iii | 180.0 | Naix—F1—Naxxvi | 109.471 |
F1—Cd—F2vii | 101.33 (2) | Cdix—F1—Cdxxvi | 109.471 |
F1—Cd—F2vi | 78.67 (2) | Znxxvii—F2—Znxxviii | 129.80 (6) |
F2ii—Cd—F2v | 63.75 (1) | Znxxvii—F2—Naviii | 106.946 (14) |
F2ii—Cd—F2iv | 116.25 (1) | Znxxvii—F2—Cdviii | 106.946 (14) |
F1i—Cd—F2ii | 78.67 (2) | Znxxvii—F2—Naxxvi | 106.946 (14) |
F1i—Cd—F2iii | 101.33 (2) | Znxxvii—F2—Cdxxvi | 106.946 (14) |
F2ii—Cd—F2vi | 63.75 (1) | Znxxviii—F2—Naviii | 106.946 (14) |
F2iii—Cd—F2ii | 180.0 | Znxxviii—F2—Cdviii | 106.946 (14) |
F1i—Cd—F2v | 101.33 (2) | Znxxviii—F2—Naxxvi | 106.946 (14) |
F1i—Cd—F2iv | 78.67 (2) | Znxxviii—F2—Cdxxvi | 106.946 (14) |
F2iii—Cd—F2iv | 63.75 (1) | | |
Symmetry codes: (i) −x, −y, −z; (ii) −y, x−1/4, z−1/4; (iii) y, −x+1/4, −z+1/4; (iv) −x, z−1/4, y−1/4; (v) x, −z+1/4, −y+1/4; (vi) −z+1/4, −x+1/4, y; (vii) z−1/4, x−1/4, −y; (viii) −y, x+1/4, z+1/4; (ix) −x+1/4, −y+1/4, z; (x) x+1/2, y+1/2, z; (xi) −x+1/2, −y+1/2, −z+1; (xii) z, x+1/2, y+1/2; (xiii) −z+1, −x+1/2, −y+1/2; (xiv) x+1/4, −z+1, y+1/4; (xv) −x+3/4, z, −y+3/4; (xvi) −y+1/2, x+1/4, z+3/4; (xvii) −y+1/2, x+3/4, z+1/4; (xviii) −x+1/4, −y+3/4, z+1/2; (xix) z−1/2, x, y+1/2; (xx) −z+1/2, −x, −y+1/2; (xxi) −x+1/2, z−1/4, y+1/4; (xxii) x, −z+3/4, −y+3/4; (xxiii) −z+3/4, −x+1/4, y+1/2; (xxiv) z−1/4, x+1/4, −y+1/2; (xxv) x−1/4, −z+1/2, y+1/4; (xxvi) y+1/4, −x, z+1/4; (xxvii) x−1/2, y−1/2, z; (xxviii) −x+3/4, −y+3/4, z. |
Bond valence sums calculated using the parameters of Brese & O'Keeffe
(1991) for NaCdZn2F7, NaCaMg2F7 (Oliveira et al.,
2004) and NaSrMg2F7 (Kubel & Dundjerski, 2001). Numbers in
parentheses refer to calculated bond valence sums assuming that the A site is
occupied by the mono- or divalent cation only. topatom | NaCdZn2F7 | NaCaMg2F7 | NaSrMg2F7 |
A (Na,Cd/Ca/Sr) | 1.28 (1.05,1.51) | 1.34 (1.05,1.63) | 1.56 (0.88,2.23) |
B (Zn/Mg) | 2.04 | 2.05 | 1.98 |
F1 | 1.06 | 1.18 | 1.46 |
F2 | 0.96 | 0.93 | 0.93 |
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