Structure of a high-pressure phase of vanadium pentoxide, β-V₂O₅

A high-pressure phase of vanadium pentoxide, denoted β-V₂O₅, has been prepared at P = 6.0 GPa and T = 1073 K. The crystal structure of β-V₂O₅ has been studied by X-ray and neutron powder diffraction, and high-resolution transmission electron microscopy. The V atoms are six-coordinated within distorted VO₆ octahedra. The structure is built up of quadruple units of edge-sharing VO₆ octahedra linked by sharing edges along [010] and mutually connected by sharing corners along [001]. This arrangement forms layers of V₄O₁₀ composition in planes parallel to (100). The layers are mutually held together by weak forces. β-V₂O₅ is metastable and transforms to α-V₂O₅ at 643–653 K under ambient pressure. Structural relationships between β- and α-V₂O₅, and between β-V₂O₅ and B-Ta₂O₅-type structures are discussed. The high-pressure β-V₂O₅ layer structure can be considered as the parent of a new series of vanadium oxide bronzes with cations intercalated between the layers.

Computing details

For both compounds, program(s) used to refine structure: GSAS.

Figures

(I) divanadium pentoxide

Crystal data

O5V2	V = 159.69 (1) Å^3
Mr = 181.88	Z = 2
Monoclinic, P21/m	Dx = 3.783 (1) Mg m^−3 Dm = 3.603 (7) Mg m^−3 Dm measured by pycnometrical
Hall symbol: -P 2yb	Neutron radiation, λ = 1.47 Å
a = 7.1140 (2) Å	T = 293 K
b = 3.57177 (10) Å	dark red
c = 6.28460 (17) Å	cylindrical diameter 9 mm, ? × ? × ? mm
β = 90.069 (3)°	Specimen preparation: Prepared at 1073 K and 6(10^6) kPa, cooled at 6000 K min−1

Data collection

Neutron powder diffractometer, NPD	Data collection mode: Debye Sherrer
Radiation source: nuclear reactor	Scan method: step
Specimen mounting: packed powder pellet	2θmin = 8.153°, 2θmax = 133.433°, 2θstep = 0.08°

Refinement

Refinement on Inet	χ^2 = 1.145
Rp = 0.030	1567 data points
Rwp = 0.040	42 parameters
Rexp = 0.024	(Δ/σ)max = 0.04

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
V1	0.0998 (7)	0.25	0.8103 (8)	0.014 (3)*
V2	0.2773 (5)	0.25	0.2557 (11)	0.015 (2)*
O1	0.8241 (5)	0.75	0.4374 (7)	0.0053 (9)*
O2	0.9693 (5)	0.25	0.1464 (7)	0.0127 (10)*
O3	0.4914 (6)	0.25	0.3248 (7)	0.0136 (11)*
O4	0.3012 (5)	0.25	0.9576 (7)	0.0084 (9)*
O5	0.1992 (5)	0.75	0.2627 (7)	0.0048 (8)*

Geometric parameters (Å, º)

V1—O1^i	1.649 (6)	V2—O1^i	2.060 (8)
V1—O2^ii	2.308 (6)	V2—O2^v	2.295 (6)
V1—O2^i	1.8724 (18)	V2—O3	1.583 (6)
V1—O2^iii	1.8724 (18)	V2—O4^vi	1.882 (8)
V1—O4	1.704 (7)	V2—O5^vii	1.8708 (15)
V1—O5^iv	2.176 (6)	V2—O5	1.8708 (15)
O1^i—V1—O2^ii	175.5 (4)	O1^i—V2—O2^v	86.9 (2)
O1^i—V1—O2^i	102.9 (2)	O1^i—V2—O3	94.7 (4)
O1^i—V1—O2^iii	102.9 (2)	O1^i—V2—O4^vi	164.7 (3)
O1^i—V1—O4	103.7 (3)	O1^i—V2—O5^vii	82.8 (2)
O1^i—V1—O5^iv	97.1 (3)	O1^i—V2—O5	82.8 (2)
O2^ii—V1—O2^i	76.2 (2)	O2^v—V2—O3	178.5 (5)
O2^ii—V1—O2^iii	76.2 (2)	O2^v—V2—O4^vi	77.8 (3)
O2^ii—V1—O4	80.9 (3)	O2^v—V2—O5^vii	73.95 (17)
O2^ii—V1—O5^iv	78.4 (2)	O2^v—V2—O5	73.95 (17)
O2^i—V1—O2^iii	145.0 (4)	O3—V2—O4^vi	100.7 (3)
O2^i—V1—O4	98.2 (2)	O3—V2—O5^vii	106.21 (18)
O2^i—V1—O5^iv	76.91 (19)	O3—V2—O5	106.21 (18)
O2^iii—V1—O4	98.2 (2)	O4^vi—V2—O5^vii	92.9 (3)
O2^iii—V1—O5^iv	76.91 (19)	O4^vi—V2—O5	92.9 (3)
O4—V1—O5^iv	159.3 (4)	O5^vii—V2—O5	145.3 (3)

Symmetry codes: (i) −x+1, y−1/2, −z+1; (ii) x−1, y, z+1; (iii) −x+1, y+1/2, −z+1; (iv) −x, y−1/2, −z+1; (v) x−1, y, z; (vi) x, y, z−1; (vii) x, y−1, z.

(II) divanadium pentoxide

Crystal data

O5V2	Z = 2
Mr = 181.88	F(000) = 172.0
Monoclinic, P21/m	Dx = 3.783 (1) Mg m^−3 Dm = 3.603 (7) Mg m^−3 Dm measured by pycnometrical
Hall symbol: -P 2yb	Cu Kα radiation, λ = 1.54056 Å
a = 7.1140 (2) Å	µ = 48.24 mm^−1
b = 3.57177 (10) Å	T = 293 K
c = 6.28460 (17) Å	dark red
β = 90.069 (3)°	flat sheet, ? × ? × ? mm
V = 159.69 (1) Å^3	Specimen preparation: Prepared at 1073 K and 6(10^6) kPa, cooled at 6000 K min−1

Data collection

Stoe Stadi/P diffractometer	Data collection mode: transmission
Radiation source: sealed X-ray tube	Scan method: step
Ge (111) monochromator	2θmin = 5.0°, 2θmax = 88.94°, 2θstep = 0.02°
Specimen mounting: drifted powder on Kapton film

Refinement

Refinement on Inet	χ^2 = 1.145
Rp = 0.015	4198 data points
Rwp = 0.020	49 parameters
Rexp = 0.029	(Δ/σ)max = 0.04

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
V1	0.0998 (7)	0.25	0.8103 (8)	0.014 (3)*
V2	0.2773 (5)	0.25	0.2557 (11)	0.015 (2)*
O1	0.8241 (5)	0.75	0.4374 (7)	0.0053 (9)*
O2	0.9693 (5)	0.25	0.1464 (7)	0.0127 (10)*
O3	0.4914 (6)	0.25	0.3248 (7)	0.0136 (11)*
O4	0.3012 (5)	0.25	0.9576 (7)	0.0084 (9)*
O5	0.1992 (5)	0.75	0.2627 (7)	0.0048 (8)*

Geometric parameters (Å, º)

V1—O1^i	1.649 (6)	V2—O1^i	2.060 (8)
V1—O2^ii	2.308 (6)	V2—O2^v	2.295 (6)
V1—O2^i	1.8724 (18)	V2—O3	1.583 (6)
V1—O2^iii	1.8724 (18)	V2—O4^vi	1.882 (8)
V1—O4	1.704 (7)	V2—O5^vii	1.8708 (15)
V1—O5^iv	2.176 (6)	V2—O5	1.8708 (15)
O1^i—V1—O2^ii	175.5 (4)	O1^i—V2—O2^v	86.9 (2)
O1^i—V1—O2^i	102.9 (2)	O1^i—V2—O3	94.7 (4)
O1^i—V1—O2^iii	102.9 (2)	O1^i—V2—O4^vi	164.7 (3)
O1^i—V1—O4	103.7 (3)	O1^i—V2—O5^vii	82.8 (2)
O1^i—V1—O5^iv	97.1 (3)	O1^i—V2—O5	82.8 (2)
O2^ii—V1—O2^i	76.2 (2)	O2^v—V2—O3	178.5 (5)
O2^ii—V1—O2^iii	76.2 (2)	O2^v—V2—O4^vi	77.8 (3)
O2^ii—V1—O4	80.9 (3)	O2^v—V2—O5^vii	73.95 (17)
O2^ii—V1—O5^iv	78.4 (2)	O2^v—V2—O5	73.95 (17)
O2^i—V1—O2^iii	145.0 (4)	O3—V2—O4^vi	100.7 (3)
O2^i—V1—O4	98.2 (2)	O3—V2—O5^vii	106.21 (18)
O2^i—V1—O5^iv	76.91 (19)	O3—V2—O5	106.21 (18)
O2^iii—V1—O4	98.2 (2)	O4^vi—V2—O5^vii	92.9 (3)
O2^iii—V1—O5^iv	76.91 (19)	O4^vi—V2—O5	92.9 (3)
O4—V1—O5^iv	159.3 (4)	O5^vii—V2—O5	145.3 (3)

Symmetry codes: (i) −x+1, y−1/2, −z+1; (ii) x−1, y, z+1; (iii) −x+1, y+1/2, −z+1; (iv) −x, y−1/2, −z+1; (v) x−1, y, z; (vi) x, y, z−1; (vii) x, y−1, z.