research papers
The single-crystal structure of a β′-copper vanadium bronze, Cu0.63V2O5, has been studied at room temperature and 9.6 K, and compared with that of the β-sodium vanadium bronze, Na0.33V2O5, structure. No convincing evidence to oppose an assignment of centrosymmetric C2/m symmetry to the structure was identified using the X-ray data. A subsequent convergent beam electron diffraction (CBED) experiment was performed and confirmed the C2/m space group. The oxygen–vanadium atom framework of Cu0.63V2O5 is close to that of Na0.33V2O5. However, in the copper compound the Cu atoms are located in two positions: Cu1 in the 4(i) position with x = 0.541, y = 0 and z = 0.345, and Cu2 in the 8(j) position with x = 0.529, y = 0.038 and z = 0.357. The crystal structure changes little with temperature. Disorder of the Cu ion over two sites is seen at 9.6 K. This suggests that distribution of the Cu atoms over two sites is of a more static than dynamic nature.
Keywords: oxygen vanadium bronzes; X-ray diffraction; convergent beam electron diffraction; electron density distribution.
Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108768104027739/av5018sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108768104027739/av5018sup2.hkl |
Computing details top
Data reduction: Xtal DIFDAT ADDREF ABSORB SORTRF; program(s) used to solve structure: Xtal; program(s) used to refine structure: Xtal CRYLSQ; molecular graphics: Xtal; software used to prepare material for publication: Xtal CIFIO.
(ozcult) top
Crystal data top
Cu0.63O5V2 | F(000) = 624.8 |
Mr = 221.59 | Dx = 4.147 Mg m−3 |
Monoclinic, C2/m | Mo Kα radiation, λ = 0.7093 Å |
Hall symbol: -c 2y | Cell parameters from 16 reflections |
a = 15.100 (1) Å | θ = 2.1–50.1° |
b = 3.6382 (2) Å | µ = 8.79 mm−1 |
c = 10.0595 (7) Å | T = 10 K |
β = 105.585 (6)° | Rectangular, black |
V = 532.32 (6) Å3 | 0.27 × 0.18 × 0.17 mm |
Z = 6 |
Data collection top
HUBER 512 diffractometer | 3041 reflections with F > .00 sig(F ) |
ω/2θ scans | Rint = 0.021 |
Absorption correction: analytical ? | θmax = 50.0°, θmin = 2.1° |
Tmin = 0.268, Tmax = 0.381 | h = −32→32 |
11127 measured reflections | k = −7→7 |
3051 independent reflections | l = −21→21 |
Refinement top
Refinement on F | 0 constraints |
Least-squares matrix: full | Weighting scheme based on measured s.u.'s |
R[F2 > 2σ(F2)] = 0.018 | (Δ/σ)max = 1.956 |
wR(F2) = 0.019 | Δρmax = 0.77 (7) e Å−3 |
S = 2.65 | Δρmin = −1.78 (7) e Å−3 |
3041 reflections | Extinction correction: Zachariasen, Eq22 p292 "Cryst. Comp." Munksgaard 1970 |
83 parameters | Extinction coefficient: 23300 (300) |
0 restraints |
Crystal data top
Cu0.63O5V2 | V = 532.32 (6) Å3 |
Mr = 221.59 | Z = 6 |
Monoclinic, C2/m | Mo Kα radiation |
a = 15.100 (1) Å | µ = 8.79 mm−1 |
b = 3.6382 (2) Å | T = 10 K |
c = 10.0595 (7) Å | 0.27 × 0.18 × 0.17 mm |
β = 105.585 (6)° |
Data collection top
HUBER 512 diffractometer | 3051 independent reflections |
Absorption correction: analytical ? | 3041 reflections with F > .00 sig(F ) |
Tmin = 0.268, Tmax = 0.381 | Rint = 0.021 |
11127 measured reflections |
Refinement top
R[F2 > 2σ(F2)] = 0.018 | 0 restraints |
wR(F2) = 0.019 | (Δ/σ)max = 1.956 |
S = 2.65 | Δρmax = 0.77 (7) e Å−3 |
3041 reflections | Δρmin = −1.78 (7) e Å−3 |
83 parameters |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
x | y | z | Uiso*/Ueq | Occ. (<1) | |
CU1 | 0.5412 (3) | 0.00000 | 0.3446 (3) | 0.0052 (3) | .429 (14) |
CU2 | 0.5286 (4) | −0.0379 (19) | 0.3575 (4) | 0.0104 (5) | .254 (7) |
V1 | 0.332203 (10) | 0.00000 | 0.089222 (15) | 0.00281 (4) | |
V2 | 0.113648 (12) | 0.00000 | 0.121234 (17) | 0.00556 (5) | |
V3 | 0.287002 (10) | 0.00000 | 0.406261 (15) | 0.00321 (4) | |
O1 | 0.00000 | 0.00000 | 0.00000 | 0.0065 (3) | |
O2 | 0.18862 (5) | 0.00000 | −0.04394 (7) | 0.00472 (19) | |
O3 | 0.36765 (5) | 0.00000 | −0.08718 (7) | 0.00475 (19) | |
O4 | 0.43233 (5) | 0.00000 | 0.20060 (7) | 0.0062 (2) | |
O5 | 0.26029 (5) | 0.00000 | 0.22253 (7) | 0.0049 (2) | |
O6 | 0.09558 (5) | 0.00000 | 0.27665 (7) | 0.0058 (2) | |
O7 | 0.24449 (5) | 0.00000 | 0.57618 (7) | 0.0051 (2) | |
O8 | 0.39945 (5) | 0.00000 | 0.45988 (7) | 0.0065 (2) |
Atomic displacement parameters (Å2) top
U11 | U22 | U33 | U12 | U13 | U23 | |
CU1 | 0.0047 (4) | 0.0070 (3) | 0.0032 (2) | 0.00000 | −0.0004 (2) | 0.00000 |
CU2 | 0.0072 (5) | 0.0181 (9) | 0.0038 (3) | 0.0044 (6) | −0.0019 (3) | −0.0022 (4) |
V1 | 0.00296 (4) | 0.00238 (5) | 0.00293 (4) | 0.00000 | 0.00054 (3) | 0.00000 |
V2 | 0.01055 (6) | 0.00232 (5) | 0.00586 (5) | 0.00000 | 0.00573 (4) | 0.00000 |
V3 | 0.00421 (4) | 0.00255 (5) | 0.00278 (4) | 0.00000 | 0.00078 (3) | 0.00000 |
O1 | 0.0036 (3) | 0.0049 (3) | 0.0103 (4) | 0.00000 | 0.0007 (3) | 0.00000 |
O2 | 0.0051 (2) | 0.0034 (2) | 0.0054 (2) | 0.00000 | 0.00106 (16) | 0.00000 |
O3 | 0.0067 (2) | 0.0031 (2) | 0.0052 (2) | 0.00000 | 0.00283 (17) | 0.00000 |
O4 | 0.0045 (2) | 0.0070 (3) | 0.0061 (2) | 0.00000 | −0.00027 (17) | 0.00000 |
O5 | 0.0063 (2) | 0.0044 (2) | 0.0041 (2) | 0.00000 | 0.00174 (16) | 0.00000 |
O6 | 0.0065 (2) | 0.0070 (3) | 0.0043 (2) | 0.00000 | 0.00206 (17) | 0.00000 |
O7 | 0.0076 (2) | 0.0035 (2) | 0.0045 (2) | 0.00000 | 0.00242 (17) | 0.00000 |
O8 | 0.0056 (2) | 0.0081 (3) | 0.0049 (2) | 0.00000 | 0.00011 (17) | 0.00000 |
Experimental details
Crystal data | |
Chemical formula | Cu0.63O5V2 |
Mr | 221.59 |
Crystal system, space group | Monoclinic, C2/m |
Temperature (K) | 10 |
a, b, c (Å) | 15.100 (1), 3.6382 (2), 10.0595 (7) |
β (°) | 105.585 (6) |
V (Å3) | 532.32 (6) |
Z | 6 |
Radiation type | Mo Kα |
µ (mm−1) | 8.79 |
Crystal size (mm) | 0.27 × 0.18 × 0.17 |
Data collection | |
Diffractometer | HUBER 512 diffractometer |
Absorption correction | Analytical |
Tmin, Tmax | 0.268, 0.381 |
No. of measured, independent and observed [F > .00 sig(F )] reflections | 11127, 3051, 3041 |
Rint | 0.021 |
(sin θ/λ)max (Å−1) | 1.080 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.018, 0.019, 2.65 |
No. of reflections | 3041 |
No. of parameters | 83 |
(Δ/σ)max | 1.956 |
Δρmax, Δρmin (e Å−3) | 0.77 (7), −1.78 (7) |
Computer programs: Xtal DIFDAT ADDREF ABSORB SORTRF, Xtal CRYLSQ, Xtal CIFIO.