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The title compound, γ-vanadium germanium oxide, was prepared as polycrystalline material by conventional solid-state reactions starting from α-quartz-type GeO2 and V2O5 in a K2CO3 flux at 1123 K. Some of the Ge4+ cations were replaced by V5+, leading to a rutile-type phase where charge neutrality is accomplished by the presence of vacancies. X-ray photoelectron spectroscopy (XPS) confirms the presence of V5+ in this compound. Its crystal structure was refined from laboratory X-ray powder data using the Rietveld method and is composed of corner- and edge-sharing MO6 octahedra where the metal positions M are statistically occupied by Ge and V. The four equatorial MO bonds lying in the (110) plane are 0.023Å shorter than the two axial bonds.
Supporting information
Key indicators
- Powder X-ray study
- T = 295 K
- Mean () = 0.000 Å
- Disorder in main residue
- R factor = 0.000
- wR factor = 0.000
- Data-to-parameter ratio = 0.0
checkCIF/PLATON results
No syntax errors found
Alert level B
PLAT301_ALERT_3_B Main Residue Disorder ......................... 29.00 Perc.
Alert level C
REFI015_ALERT_1_C _refine_ls_shift/su_max is missing
Maximum shift/s.u. ratio after final refinement cycle.
The following tests will not be performed
SHFSU_01
REFI023_ALERT_1_C _refine_diff_density_max is missing
Maximum value of final difference map (e A-3).
The following tests will not be performed
DIFMN_01,DIFMX_01,DIFMX_02
REFI024_ALERT_1_C _refine_diff_density_min is missing
Minimum value of final difference map (e A-3).
The following tests will not be performed
DIFMN_01,DIFMN_02,DIFMN_03
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings Differ .... ?
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ .... ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............ 0.50 Ratio
PLAT077_ALERT_4_C Unitcell contains non-integer number of atoms .. ?
PLAT180_ALERT_3_C Check Cell Rounding: # of Values Ending with 0 = 3
PLAT799_ALERT_4_C Numeric Label on Displacement Par. Record ...... ?
0 ALERT level A = In general: serious problem
1 ALERT level B = Potentially serious problem
9 ALERT level C = Check and explain
0 ALERT level G = General alerts; check
6 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
0 ALERT type 2 Indicator that the structure model may be wrong or deficient
2 ALERT type 3 Indicator that the structure quality may be low
2 ALERT type 4 Improvement, methodology, query or suggestion
0 ALERT type 5 Informative message, check
Data collection: DIFFRAC/AT (Siemens, 1993); cell refinement: FULLPROF (Rodríguez-Carvajal, 2001; data reduction: FULLPROF; program(s) used to solve structure: coordinates taken from an isotypic compound; program(s) used to refine structure: FULLPROF; molecular graphics: DIAMOND (Crystal Impact, 2005); software used to prepare material for publication: FULLPROF.
γ-vanadium germanium oxide
top
Crystal data top
Ge0.74V0.21O2 | Z = 2 |
Mr = 96.43 | F(000) = 88.1 |
Tetragonal, P42/mnm | Dx = 5.77 Mg m−3 |
Hall symbol: -P 4n 2n | Cu Kα radiation, λ = 1.54175 Å |
a = 4.4001 (1) Å | T = 295 K |
c = 2.8670 (1) Å | brown |
V = 55.51 (1) Å3 | flat_sheet, 20 × 20 mm |
Data collection top
Bruker Advance D8 diffractometer | Data collection mode: reflection |
Radiation source: sealed X-ray tube, Cu Kα | Scan method: step |
Graphite monochromator | 2θmin = 5°, 2θmax = 110°, 2θstep = 0.02° |
Specimen mounting: packed powder sample container | |
Refinement top
Least-squares matrix: full with fixed elements per cycle | 5251 data points |
Rp = 0.05 | Profile function: pseudo-Voigt modified by Thompson et al. (1987) |
Rwp = 0.07 | 18 parameters |
Rexp = 0.03 | Weighting scheme based on measured s.u.'s |
RBragg = 0.02 | Background function: The background was refined first by means of a linear interpolation
between 100 background points with refinable heights. At the end of the
refinement, the values for all of these heights of the background were
fixed. |
R(F2) = 0.02 | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
V | 0.00000 | 0.00000 | 0.00000 | 0.0053 (1) | 0.21 (2) |
Ge | 0.00000 | 0.00000 | 0.00000 | 0.0053 (1) | 0.74 (2) |
O | 0.3054 (3) | 0.3054 (3) | 0.00000 | 0.0025 (1) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
? | ? | ? | ? | ? | ? | ? |
Geometric parameters (Å, º) top
Ge—O | 1.900 (1) | Ge—Oi | 1.877 (1) |
| | | |
O—Ge—Oi | 90.00 (8) | | |
Symmetry code: (i) −y+1/2, x−1/2, z−1/2. |
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