The alluaudite-type crystal structures of Na2(Fe/Co)2Co(VO4)3 and Ag2(Fe/Co)2Co(VO4)3

Hadouchi, M.; Assani, A.; Saadi, M.; El Ammari, L.

doi:10.1107/S2056989016009981

research communications

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 72| Part 7| July 2016| Pages 1017-1020

https://doi.org/10.1107/S2056989016009981

Open

access

The alluaudite-type crystal structures of Na₂(Fe/Co)₂Co(VO₄)₃ and Ag₂(Fe/Co)₂Co(VO₄)₃

Mohammed Hadouchi,^a ^* Abderrazzak Assani,^a Mohamed Saadi ^a and Lahcen El Ammari ^a

^aLaboratoire de Chimie du Solide Appliquée, Faculty of Sciences, Mohammed V University in Rabat, Avenue Ibn Battouta, BP 1014, Rabat, Morocco
^*Correspondence e-mail: mhadouchi@yahoo.com

Edited by M. Weil, Vienna University of Technology, Austria (Received 7 May 2016; accepted 19 June 2016; online 24 June 2016)

Single crystals of the title compounds, disodium di(cobalt/iron) cobalt tris(orthovanadate), Na₂(Fe/Co)₂Co(VO₄)₃, and disilver di(cobalt/iron) cobalt tris(orthovanadate), Ag₂(Fe/Co)₂Co(VO₄)₃, were grown from a melt consisting of stoichiometric mixtures of three metallic cation precursors and vanadium pentoxide. The difficulty to distinguish between cobalt and iron by using X-ray diffraction alone forced us to explore several models, assuming an oxidation state of +II for Co and +III for Fe and a partial cationic disorder in the Wyckoff site 8f containing a mixture of Co and Fe with a statistical distribution for the Na compound and an occupancy ratio of 0.4875:0.5125 (Co:Fe) for the Ag compound. The alluaudite-type structure is made up from [10-1] chains of [(Co,Fe)₂O₁₀] double octahedra linked by highly distorted [CoO₆] octahedra via a common edge. The chains are linked through VO₄ tetrahedra, forming polyhedral sheets perpendicular to [010]. The stacking of the sheets defines two types of channels parallel to [001] where the Na⁺ cations (both with full occupancy) or Ag⁺ cations (one with occupancy 0.97) are located.

Keywords: crystal structure; transition metal vanadates; solid-state reaction synthesis; alluaudite-like structure.

CCDC references: 1486597; 1486596

1. Chemical context

The needs of the society on the `energy front' is one of the greatest challenges for present and future times. Materials with three-dimensional framework structures delimiting channels, as built of transition metal cations and polyanions (XO₄)ⁿ⁻, have become a subject of very intensive research worldwide since the discovery of the electrochemical activity of LiFePO₄ (Padhi et al., 1997a ,b ). Hence, new transition metal-based materials adopting open three-dimensional framework structures have been synthesized and investigated by us over the last years. Thereby our attention has focused on the synthesis and characterization of new materials belonging to the family of alluaudites that, according to Moore (1971 ), has the general formula A(1)A(2)M(1)M(2)₂(XO₄)₃. The A sites may be occupied by larger mono- and/or divalent cations, while the M sites correspond to bi- or trivalent transition metal cations in an octahedral environment. Alluaudite-like compounds, having open-framework structures, allow a certain prediction of physical properties and promising practical applications in several fields. For instance, alluaudite-like compounds exhibit electronic and/or ionic conductivity, as has been shown by Warner et al. (1993 , 1994 ), which make them worthy of investigating their electrochemical performance. Mainly, several alluaudite-like phosphates have been tested as anode and/or cathode materials in Li-ion and/or Na-ion batteries. For example, Li_0.78Na_0.22MnPO₄ was proposed by Kim et al. (2014 ) as a promising new positive electrode for Li-ion batteries. The sulfates Na_2.44Mn_1.79(SO₄)₃ (Dwibedi et al., 2015 ) and Na_2+2xFe_2−x(SO₄)₃ (Dwibedi et al., 2016 ) were tested as electroactive materials for Na-ion batteries. In this context, we have investigated pseudo-ternary A₂O/MO/P₂O₅, pseudo-quaternary A₂O/MO/Fe₂O₃/P₂O₅, and more recently, A₂O/MO/Fe₂O₃/V₂O₅ systems synthesized via hydrothermal or solid-state routes, resulting in new alluaudite-like phosphates AgMg₃(HPO₄)₂PO₄ (Assani et al., 2011 ), NaMg₃(HPO₄)₂PO₄ (Ould Saleck et al., 2015 ), Na₂Co₂Fe(PO₄)₃ (Bouraima et al., 2015 ), Na_1.67Zn_1.67Fe_1.33(PO₄)₃ (Khmiyas et al., 2015 ), and most lately, the first alluaudite-like vanadate (Na_0.70)(Na_0.70Mn_0.30)(Fe³⁺/Fe²⁺)₂Fe²⁺(VO₄)₃ (Benhsina et al., 2016 ). As a continuation of our studies of phases with alluaudite-like structures, the present work reports details of the synthesis and crystal structures of the compounds M₂(Fe/Co)₂Co(VO₄)₃ (M = Na, Ag).

2. Structural commentary

The two alluaudite-like vanadates, Na₂(Fe/Co)₂Co(VO₄)₃ and Ag₂(Fe/Co)₂Co(VO₄)₃, are isotypic. In the structure of Na₂(Fe/Co)₂Co(VO₄)₃ all sites are fully occupied and only the cationic site on Wyckoff position 8f shows disorder with a statistical distribution of Co and Fe, assuming oxidation state +II for Co and +III for Fe. In the structure of Ag₂(Fe/Co)₂Co(VO₄)₃ a small deficit in the Ag2 site was considered (occupancy 0.97) that is compensated by a slight excess of Fe (occupancy 0.51) compared with Co (occupancy 0.49) in the 8f mixed site, again under the assumption of oxidation state +II for Co and +III for Fe. The (Fe1,Co1) and Co2 sites have octahedral environments while the vanadium atoms are located in tetrahedral environments. The sequence of different polyhedra forming the principal building units are shown in Figs. 1 and 2. The mixed-occupied sites containing the (Fe1,Co1) atoms form [(Co,Fe)₂O₁₀] dimers through edge-sharing of a single octahedron and are linked by highly distorted [CoO₆] octahedra. The linkage of alternating [CoO₆] octahedra and [(Co,Fe)₂O₁₀] double octahedra leads to the formation of infinite chains along the [10 $[\overline{1}]$ ] direction (Fig. 3). The connection of these chains through VO₄ tetrahedra makes up sheets perpendicular to [010], as shown in Fig. 4. The stacking of these sheets defines an open three-dimensional framework delimiting two types of channels parallel to [001] where the M⁺ cations (M = Na, Ag) are situated (Fig. 5). In the sodium compound, the Na1 site is coordinated by eight oxygen atoms with Na1—O distances in the range between 2.4118 (14) and 2.8820 (15) Å, while Na2 is surrounded by six oxygen atoms in a range between 2.4347 (14) and 2.780 (2) Å. In the silver compound, the Ag1 site is coordinated by six oxygen atoms in a range between 2.4244 (12) and 2.5960 (13) Å, whereas the Ag2 site is surrounded by four oxygen atoms in a range between 2.4708 (14) and 2.4779 (14) Å.

Figure 1
The principal building units in the structure of Na₂(Fe/Co)₂Co(VO₄)₃. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) x, −y + 1, z + $[{1\over 2}]$ ; (ii) −x + $[{3\over 2}]$ , −y + $[{3\over 2}]$ , −z + 2; (iii) x, y, z + 1; (iv) −x + $[{3\over 2}]$ , −y + $[{3\over 2}]$ , −z + 1; (v) −x + 1, y, −z + $[{3\over 2}]$ ; (vi) x, y, z − 1; (vii) −x + 1, y, −z + $[{1\over 2}]$ ; (viii) x − $[{1\over 2}]$ , −y + $[{3\over 2}]$ , z − $[{1\over 2}]$ ; (ix) −x + 1, −y + 1, −z + 1; (x) x, −y + 1, z − $[{1\over 2}]$ ; (xi) −x + 2, y, −z + $[{3\over 2}]$ ; (xii) −x + 2, −y + 1, −z + 1.]

Figure 2
The principal building units in the structure of Ag₂(Fe/Co)₂Co(VO₄)₃. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) x, −y + 1, z + $[{1\over 2}]$ ; (ii) −x + $[{3\over 2}]$ , −y + $[{3\over 2}]$ , −z + 2; (iii) x, y, z + 1; (iv) −x + $[{3\over 2}]$ , −y + $[{3\over 2}]$ , −z + 1; (v) −x + 1, y, −z + $[{3\over 2}]$ ; (vi) x, y, z − 1; (vii) −x + 1, y, −z + $[{1\over 2}]$ ; (viii) x − $[{1\over 2}]$ , −y + $[{3\over 2}]$ , z − $[{1\over 2}]$ ; (ix) −x + 1, −y + 1, −z + 1; (x) x, −y + 1, z − $[{1\over 2}]$ ; (xi) −x + 2, y, −z + $[{3\over 2}]$ ; (xii) −x + 2, −y + 1, −z + 1.]

Figure 3
Edge-sharing octahedra forming an infinite zigzag chain running along [10 $[\overline{1}]$ ]. Data from Na₂(Fe/Co)₂Co(VO₄)₃.

Figure 4
A sheet perpendicular to [010], resulting from the connection of individual chains via VO₄ tetrahedra. Data from Na₂(Fe/Co)₂Co(VO₄)₃.

Figure 5
Polyhedral representation of Na₂(Fe/Co)₂Co(VO₄)₃ showing sodium cations in the channels extending along [001].

3. Synthesis and crystallization

The target compounds were obtained by solid-state reactions. A starting mixture of metallic iron (+ a few drops of HNO₃), Co(CH₃COO)₂·4H₂O, NH₄VO₃ and NaNO₃ or AgNO₃ was mixed in molar ratios M: Co: Fe: V = 2: 2: 1: 3 (M = Na or Ag). The mixture was placed in a platinum crucible and then heated gradually until melting (1253 K). Single crystals were obtained by cooling the molten product to room temperature at rate of 5 Kh⁻¹. The resulting mixtures contained pink crystals (for M = Na) or green crystals (for M = Ag) of a suitable size for the X-ray diffraction study. The powder X-ray diffraction patterns are in good agreement with the simulated patterns, generated from the final structure models of the two compounds (see supplementary material).

4. Refinement

Crystal data, data collection and structure refinement details for both structures are summarized in Table 1.

Table 1
Experimental details

	(I)	(II)
Crystal data
Chemical formula	Na₂(Co_0.5Fe_0.5)₂Co(VO₄)₃	Ag_1.97(Co_0.49Fe_0.51)₂Co(VO₄)₃
M_r	564.51	730.96
Crystal system, space group	Monoclinic, C2/c	Monoclinic, C2/c
Temperature (K)	296	296
a, b, c (Å)	11.7258 (2), 12.7819 (2), 6.8264 (1)	11.7846 (4), 12.8314 (4), 6.8064 (2)
β (°)	111.069 (1)	111.001 (1)
V (Å³)	954.73 (3)	960.85 (5)
Z	4	4
Radiation type	Mo Kα	Mo Kα
μ (mm⁻¹)	7.85	11.60
Crystal size (mm)	0.32 × 0.25 × 0.19	0.34 × 0.22 × 0.17

Data collection
Diffractometer	Bruker X8 APEX	Bruker X8 APEX
Absorption correction	Multi-scan (SADABS; Bruker, 2009 )	Multi-scan (SADABS; Bruker, 2009)
T_min, T_max	0.572, 0.747	0.439, 0.747
No. of measured, independent and observed [I > 2σ(I)] reflections	17675, 2094, 1893	15366, 2113, 1987
R_int	0.047	0.039
(sin θ/λ)_max (Å⁻¹)	0.806	0.806

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.022, 0.054, 1.10	0.018, 0.041, 1.14
No. of reflections	2094	2113
No. of parameters	95	104
Δρ_max, Δρ_min (e Å⁻³)	0.88, −1.00	0.80, −1.66
Computer programs: APEX2 and SAINT (Bruker, 2009), SHELXT2014 (Sheldrick, 2015a ), SHELXL2014 (Sheldrick, 2015b ), ORTEP-3 for Windows (Farrugia, 2012 ), DIAMOND (Brandenburg, 2006 ) and publCIF (Westrip, 2010 ).

As a matter of fact, the distinction between cobalt and iron by X-ray diffraction is nearly impossible. Therefore we have examined several crystallographic models during crystal structure refinements of the title compounds. Based on the stoichiometric ratio of 1:2 for iron and cobalt in the starting materials, we assumed the same ratio in the crystal structures with oxidation states of +II for cobalt and and +III for iron. In the final model, Fe1 and Co1 atoms are constrained to share the same general position 8f of the space group C2/c. Electrical neutrality and bond valence sum calculations of all atoms (Brown & Altermatt, 1985 ) in the structures are in reasonable agreement with the final models. Bond valence sums (in valence units) for Na₂(Fe/Co)₂Co(VO₄)₃ are 1.07 for Na1, 0.86 for Na2, 2.24 for Co1, 1.97 for Co2, 2.69 for Fe1, 5.01 for V1, and 4.99 for V2. Values of the bond valence sums calculated for all oxygen atoms are between 1.90 and 2.07. Bond valence sums for Ag₂(Fe/Co)₂Co(VO₄)₃ are 1.01 for Ag1, O.72 for Ag2, 2.27 for Co1, 1.98 for Co2, 2.72 for Fe1, 4.99 for V1, and 4.94 for V2. The values of the O atoms are in the range 1.94 to 2.03. A very similar cationic distribution was observed by Yakubovich et al. (1977 ) in the alluaudite-type phosphate Na₂(Fe³⁺/Fe²⁺)₂Fe²⁺(PO₄)₃.

Refinement of Na₂(Fe/Co)₂Co(VO₄)₃: Co1 and Fe1 were constrained to share the same site in a statistical occupation with common displacement parameters. Reflection (132) probably was affected by the beam-stop and was omitted from the refinement. The remaining electron densities (max/min) in the final Fourier map were 0.46 Å and 0.71 Å away from atoms Na1 and Na2, respectively.

Refinement of Ag₂(Fe/Co)₂Co(VO₄)₃: The coordinates and displacement factors of Co1 and Fe1 atoms were refined independent from each other. An underoccupation of the Ag2 site was modelled with an occupancy of 0.97 which made it necessary to constrain the occupancies of the Co1 site (0.4875) and Fe1 site (0.5125) for electroneutrality. The remaining electron densities (max/min) in the final Fourier map were 0.61 Å and 0.66 Å away from Ag2.

Supporting information

CCDC references: 1486597; 1486596

Crystal structure: contains datablocks I, II, global. DOI: https://doi.org/10.1107/S2056989016009981/wm5292sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989016009981/wm5292Isup2.hkl

Structure factors: contains datablock II. DOI: https://doi.org/10.1107/S2056989016009981/wm5292IIsup3.hkl

checkCIF report

Computing details top

For both compounds, data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

(I) Disodium di(cobalt/iron) cobalt tris(orthovanadate) top

Crystal data top

Na₂(Co·Fe)₂Co(VO₄)₃	F(000) = 1068
M_r = 564.51	D_x = 3.927 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 11.7258 (2) Å	Cell parameters from 2094 reflections
b = 12.7819 (2) Å	θ = 2.5–35.0°
c = 6.8264 (1) Å	µ = 7.85 mm⁻¹
β = 111.069 (1)°	T = 296 K
V = 954.73 (3) Å³	Block, pink
Z = 4	0.32 × 0.25 × 0.19 mm

Data collection top

Bruker X8 APEX diffractometer	2094 independent reflections
Radiation source: fine-focus sealed tube	1893 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.047
φ and ω scans	θ_max = 35.0°, θ_min = 2.5°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −17→18
T_min = 0.572, T_max = 0.747	k = −20→20
17675 measured reflections	l = −10→10

Refinement top

Refinement on F²	95 parameters
Least-squares matrix: full	0 restraints
R[F² > 2σ(F²)] = 0.022	w = 1/[σ²(F_o²) + (0.0186P)² + 2.754P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.054	(Δ/σ)_max = 0.001
S = 1.10	Δρ_max = 0.88 e Å⁻³
2094 reflections	Δρ_min = −1.00 e Å⁻³

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Fe1	0.79142 (2)	0.66131 (2)	0.88043 (4)	0.00595 (6)	0.5
Co1	0.79142 (2)	0.66131 (2)	0.88043 (4)	0.00595 (6)	0.5
Co2	0.5000	0.73184 (3)	0.2500	0.00727 (7)
V1	0.77138 (3)	0.61298 (2)	0.38340 (4)	0.00555 (6)
V2	0.5000	0.70722 (3)	0.7500	0.00629 (8)
Na1	0.5000	0.5000	0.5000	0.0123 (2)
Na2	1.0000	0.50245 (14)	0.7500	0.0257 (3)
O1	0.84286 (13)	0.67273 (11)	0.6264 (2)	0.0102 (2)
O2	0.62045 (12)	0.60248 (11)	0.3329 (2)	0.0116 (2)
O3	0.78619 (13)	0.68309 (11)	0.1758 (2)	0.0113 (2)
O6	0.61413 (13)	0.62261 (11)	0.7671 (2)	0.0120 (2)
O5	0.53637 (12)	0.77735 (11)	0.9853 (2)	0.0104 (2)
O4	0.84074 (13)	0.49296 (11)	0.4032 (2)	0.0108 (2)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Fe1	0.00562 (10)	0.00715 (11)	0.00541 (10)	−0.00056 (7)	0.00237 (7)	−0.00051 (7)
Co1	0.00562 (10)	0.00715 (11)	0.00541 (10)	−0.00056 (7)	0.00237 (7)	−0.00051 (7)
Co2	0.00669 (14)	0.00821 (15)	0.00752 (13)	0.000	0.00330 (11)	0.000
V1	0.00559 (12)	0.00635 (12)	0.00449 (11)	−0.00001 (9)	0.00155 (9)	−0.00011 (8)
V2	0.00700 (17)	0.00647 (17)	0.00459 (15)	0.000	0.00113 (12)	0.000
Na1	0.0208 (6)	0.0070 (5)	0.0074 (4)	−0.0057 (4)	0.0030 (4)	−0.0015 (3)
Na2	0.0097 (5)	0.0565 (10)	0.0105 (5)	0.000	0.0031 (4)	0.000
O1	0.0115 (6)	0.0116 (6)	0.0074 (5)	−0.0037 (5)	0.0031 (4)	−0.0016 (4)
O2	0.0077 (5)	0.0107 (6)	0.0158 (6)	−0.0008 (4)	0.0035 (5)	0.0004 (5)
O3	0.0138 (6)	0.0126 (6)	0.0080 (5)	−0.0004 (5)	0.0043 (4)	0.0006 (4)
O6	0.0092 (6)	0.0098 (6)	0.0148 (6)	0.0012 (4)	0.0015 (5)	−0.0019 (5)
O5	0.0075 (5)	0.0156 (6)	0.0082 (5)	−0.0017 (5)	0.0028 (4)	−0.0025 (4)
O4	0.0102 (6)	0.0092 (6)	0.0129 (6)	0.0002 (4)	0.0042 (5)	−0.0015 (4)

Geometric parameters (Å, º) top

Fe1—O6	2.0021 (14)	V2—O6^v	1.6917 (14)
Fe1—O1	2.0359 (14)	V2—O5	1.7531 (13)
Fe1—O4ⁱ	2.0451 (14)	V2—O5^v	1.7531 (13)
Fe1—O5ⁱⁱ	2.0497 (14)	Na1—O6	2.4118 (14)
Fe1—O3ⁱⁱⁱ	2.0581 (14)	Na1—O6^ix	2.4119 (14)
Fe1—O3^iv	2.1633 (14)	Na1—O2^ix	2.4841 (14)
Co2—O5^v	2.0831 (14)	Na1—O2	2.4841 (14)
Co2—O5^vi	2.0831 (14)	Na1—O2ⁱ	2.5626 (14)
Co2—O2	2.1153 (14)	Na1—O2^vii	2.5626 (14)
Co2—O2^vii	2.1153 (14)	Na1—O6^x	2.8820 (15)
Co2—O1^iv	2.1159 (13)	Na1—O6^v	2.8820 (15)
Co2—O1^viii	2.1159 (13)	Na2—O4^xi	2.4347 (14)
V1—O2	1.6823 (14)	Na2—O4	2.4347 (14)
V1—O4	1.7188 (14)	Na2—O4ⁱ	2.4472 (15)
V1—O3	1.7374 (14)	Na2—O4^xii	2.4472 (15)
V1—O1	1.7428 (13)	Na2—O1	2.780 (2)
V2—O6	1.6917 (14)	Na2—O1^xi	2.780 (2)

O6—Fe1—O1	105.84 (6)	O6—Na1—O2^ix	104.36 (5)
O6—Fe1—O4ⁱ	90.98 (6)	O6^ix—Na1—O2^ix	75.63 (5)
O1—Fe1—O4ⁱ	88.38 (6)	O6—Na1—O2	75.64 (5)
O6—Fe1—O5ⁱⁱ	170.54 (6)	O6^ix—Na1—O2	104.37 (5)
O1—Fe1—O5ⁱⁱ	78.91 (5)	O2^ix—Na1—O2	180.0
O4ⁱ—Fe1—O5ⁱⁱ	97.39 (6)	O6—Na1—O2ⁱ	71.50 (5)
O6—Fe1—O3ⁱⁱⁱ	91.12 (6)	O6^ix—Na1—O2ⁱ	108.50 (5)
O1—Fe1—O3ⁱⁱⁱ	161.29 (6)	O2^ix—Na1—O2ⁱ	63.02 (6)
O4ⁱ—Fe1—O3ⁱⁱⁱ	99.39 (6)	O2—Na1—O2ⁱ	116.98 (6)
O5ⁱⁱ—Fe1—O3ⁱⁱⁱ	83.21 (5)	O6—Na1—O2^vii	108.50 (5)
O6—Fe1—O3^iv	81.17 (6)	O6^ix—Na1—O2^vii	71.50 (5)
O1—Fe1—O3^iv	91.00 (5)	O2^ix—Na1—O2^vii	116.98 (6)
O4ⁱ—Fe1—O3^iv	171.64 (6)	O2—Na1—O2^vii	63.02 (6)
O5ⁱⁱ—Fe1—O3^iv	90.67 (6)	O2ⁱ—Na1—O2^vii	180.0
O3ⁱⁱⁱ—Fe1—O3^iv	83.72 (5)	O6—Na1—O6^x	121.93 (6)
O5^v—Co2—O5^vi	147.57 (8)	O6^ix—Na1—O6^x	58.07 (6)
O5^v—Co2—O2	108.15 (5)	O2^ix—Na1—O6^x	114.84 (4)
O5^vi—Co2—O2	97.18 (6)	O2—Na1—O6^x	65.16 (4)
O5^v—Co2—O2^vii	97.18 (6)	O2ⁱ—Na1—O6^x	89.66 (4)
O5^vi—Co2—O2^vii	108.15 (5)	O2^vii—Na1—O6^x	90.34 (4)
O2—Co2—O2^vii	77.17 (8)	O6—Na1—O6^v	58.07 (6)
O5^v—Co2—O1^iv	85.04 (5)	O6^ix—Na1—O6^v	121.93 (6)
O5^vi—Co2—O1^iv	76.38 (5)	O2^ix—Na1—O6^v	65.16 (4)
O2—Co2—O1^iv	86.67 (5)	O2—Na1—O6^v	114.84 (4)
O2^vii—Co2—O1^iv	163.59 (6)	O2ⁱ—Na1—O6^v	90.34 (4)
O5^v—Co2—O1^viii	76.38 (5)	O2^vii—Na1—O6^v	89.66 (4)
O5^vi—Co2—O1^viii	85.04 (5)	O6^x—Na1—O6^v	180.0
O2—Co2—O1^viii	163.59 (6)	O4^xi—Na2—O4	174.29 (11)
O2^vii—Co2—O1^viii	86.67 (5)	O4^xi—Na2—O4ⁱ	91.26 (5)
O1^iv—Co2—O1^viii	109.60 (8)	O4—Na2—O4ⁱ	88.87 (5)
O2—V1—O4	112.22 (7)	O4^xi—Na2—O4^xii	88.87 (5)
O2—V1—O3	106.27 (7)	O4—Na2—O4^xii	91.26 (5)
O4—V1—O3	109.96 (7)	O4ⁱ—Na2—O4^xii	177.25 (11)
O2—V1—O1	109.92 (7)	O4^xi—Na2—O1	121.82 (7)
O4—V1—O1	105.32 (7)	O4—Na2—O1	63.31 (5)
O3—V1—O1	113.29 (7)	O4ⁱ—Na2—O1	65.58 (5)
O6—V2—O6^v	100.53 (10)	O4^xii—Na2—O1	112.08 (6)
O6—V2—O5	109.75 (7)	O4^xi—Na2—O1^xi	63.31 (5)
O6^v—V2—O5	108.41 (7)	O4—Na2—O1^xi	121.82 (7)
O6—V2—O5^v	108.42 (7)	O4ⁱ—Na2—O1^xi	112.08 (6)
O6^v—V2—O5^v	109.75 (7)	O4^xii—Na2—O1^xi	65.58 (5)
O5—V2—O5^v	118.49 (10)	O1—Na2—O1^xi	76.92 (7)
O6—Na1—O6^ix	180.0

Symmetry codes: (i) x, −y+1, z+1/2; (ii) −x+3/2, −y+3/2, −z+2; (iii) x, y, z+1; (iv) −x+3/2, −y+3/2, −z+1; (v) −x+1, y, −z+3/2; (vi) x, y, z−1; (vii) −x+1, y, −z+1/2; (viii) x−1/2, −y+3/2, z−1/2; (ix) −x+1, −y+1, −z+1; (x) x, −y+1, z−1/2; (xi) −x+2, y, −z+3/2; (xii) −x+2, −y+1, −z+1.

(II) Disilver di(cobalt/iron) cobalt tris(orthovanadate) top

Crystal data top

Ag_1.97(Co_0.49Fe_0.51)₂Co(VO₄)₃	F(000) = 1350
M_r = 730.96	D_x = 5.053 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 11.7846 (4) Å	Cell parameters from 2113 reflections
b = 12.8314 (4) Å	θ = 2.4–35.0°
c = 6.8064 (2) Å	µ = 11.60 mm⁻¹
β = 111.001 (1)°	T = 296 K
V = 960.85 (5) Å³	Block, green
Z = 4	0.34 × 0.22 × 0.17 mm

Data collection top

Bruker X8 APEX diffractometer	2113 independent reflections
Radiation source: fine-focus sealed tube	1987 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.039
φ and ω scans	θ_max = 35.0°, θ_min = 2.4°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −18→18
T_min = 0.439, T_max = 0.747	k = −20→20
15366 measured reflections	l = −9→10

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	w = 1/[σ²(F_o²) + (0.0093P)² + 2.3975P] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.018	(Δ/σ)_max = 0.001
wR(F²) = 0.041	Δρ_max = 0.80 e Å⁻³
S = 1.14	Δρ_min = −1.66 e Å⁻³
2113 reflections	Extinction correction: SHELXL2014 (Sheldrick, 2015b), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
104 parameters	Extinction coefficient: 0.00190 (7)

Special details top

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Ag1	0.0000	0.5000	0.0000	0.02187 (6)
Ag2	0.5000	0.50840 (2)	0.7500	0.02578 (6)	0.97
Co1	0.2919 (4)	0.6616 (4)	0.3791 (8)	0.0066 (12)	0.4875
Fe1	0.2923 (4)	0.6620 (4)	0.3814 (8)	0.0061 (12)	0.5125
Co2	0.0000	0.73364 (2)	0.7500	0.00755 (6)
V1	0.27106 (2)	0.38672 (2)	0.38255 (4)	0.00573 (5)
V2	0.0000	0.70581 (3)	0.2500	0.00609 (6)
O1	0.34160 (11)	0.32595 (9)	0.62391 (19)	0.0103 (2)
O2	0.28472 (11)	0.31626 (10)	0.17435 (19)	0.0109 (2)
O3	0.12124 (11)	0.39463 (10)	0.3352 (2)	0.0121 (2)
O4	0.33731 (12)	0.50845 (9)	0.3988 (2)	0.0123 (2)
O5	0.03699 (11)	0.77654 (10)	0.48520 (19)	0.0100 (2)
O6	0.11558 (11)	0.62338 (9)	0.2663 (2)	0.0114 (2)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ag1	0.03724 (13)	0.01563 (9)	0.01248 (9)	−0.01172 (8)	0.00860 (8)	−0.00330 (6)
Ag2	0.01181 (9)	0.04845 (15)	0.01618 (10)	0.000	0.00390 (8)	0.000
Co1	0.0072 (18)	0.0061 (17)	0.0085 (18)	0.0017 (12)	0.0052 (12)	−0.0004 (12)
Fe1	0.0059 (17)	0.0082 (18)	0.0032 (15)	−0.0027 (12)	0.0007 (11)	−0.0007 (11)
Co2	0.00710 (12)	0.00870 (12)	0.00779 (13)	0.000	0.00380 (10)	0.000
V1	0.00651 (10)	0.00586 (10)	0.00488 (10)	0.00018 (7)	0.00212 (8)	0.00004 (7)
V2	0.00679 (14)	0.00648 (13)	0.00465 (14)	0.000	0.00161 (11)	0.000
O1	0.0119 (5)	0.0111 (5)	0.0081 (5)	0.0027 (4)	0.0038 (4)	0.0013 (4)
O2	0.0129 (5)	0.0121 (5)	0.0083 (5)	−0.0007 (4)	0.0045 (4)	−0.0007 (4)
O3	0.0094 (5)	0.0113 (5)	0.0156 (6)	0.0007 (4)	0.0045 (4)	−0.0005 (4)
O4	0.0132 (5)	0.0087 (5)	0.0156 (6)	−0.0002 (4)	0.0060 (5)	0.0010 (4)
O5	0.0091 (5)	0.0136 (5)	0.0078 (5)	−0.0018 (4)	0.0036 (4)	−0.0019 (4)
O6	0.0088 (5)	0.0103 (5)	0.0137 (5)	0.0000 (4)	0.0024 (4)	−0.0021 (4)

Geometric parameters (Å, º) top

Ag1—O6ⁱ	2.4244 (12)	Fe1—O1ⁱⁱ	2.040 (6)
Ag1—O6	2.4244 (12)	Fe1—O5^vii	2.045 (5)
Ag1—O3ⁱⁱ	2.5051 (13)	Fe1—O2^v	2.047 (5)
Ag1—O3ⁱⁱⁱ	2.5051 (13)	Fe1—O2^viii	2.154 (5)
Ag1—O3	2.5960 (13)	Co2—O5^ix	2.0747 (12)
Ag1—O3ⁱ	2.5960 (13)	Co2—O5	2.0748 (12)
Ag2—O4	2.4708 (14)	Co2—O1^x	2.1156 (12)
Ag2—O4^iv	2.4709 (14)	Co2—O1^xi	2.1156 (12)
Ag2—O4^v	2.4779 (14)	Co2—O3^xii	2.1197 (13)
Ag2—O4^vi	2.4779 (14)	Co2—O3^v	2.1197 (13)
Co1—O6	2.001 (5)	V1—O3	1.6804 (13)
Co1—O1ⁱⁱ	2.028 (6)	V1—O4	1.7319 (12)
Co1—O4	2.028 (5)	V1—O2	1.7363 (12)
Co1—O5^vii	2.053 (5)	V1—O1	1.7375 (12)
Co1—O2^v	2.061 (5)	V2—O6	1.6965 (12)
Co1—O2^viii	2.157 (5)	V2—O6ⁱⁱⁱ	1.6965 (12)
Fe1—O6	2.007 (5)	V2—O5ⁱⁱⁱ	1.7539 (12)
Fe1—O4	2.033 (5)	V2—O5	1.7539 (12)

O6ⁱ—Ag1—O6	180.0	O6—Fe1—O5^vii	170.5 (3)
O6ⁱ—Ag1—O3ⁱⁱ	105.99 (4)	O4—Fe1—O5^vii	98.8 (2)
O6—Ag1—O3ⁱⁱ	74.01 (4)	O1ⁱⁱ—Fe1—O5^vii	79.3 (2)
O6ⁱ—Ag1—O3ⁱⁱⁱ	74.01 (4)	O6—Fe1—O2^v	90.7 (2)
O6—Ag1—O3ⁱⁱⁱ	105.99 (4)	O4—Fe1—O2^v	100.2 (2)
O3ⁱⁱ—Ag1—O3ⁱⁱⁱ	180.0	O1ⁱⁱ—Fe1—O2^v	162.1 (3)
O6ⁱ—Ag1—O3	107.57 (4)	O5^vii—Fe1—O2^v	83.95 (17)
O6—Ag1—O3	72.43 (4)	O6—Fe1—O2^viii	81.09 (17)
O3ⁱⁱ—Ag1—O3	116.87 (5)	O4—Fe1—O2^viii	170.3 (2)
O3ⁱⁱⁱ—Ag1—O3	63.13 (5)	O1ⁱⁱ—Fe1—O2^viii	90.6 (2)
O6ⁱ—Ag1—O3ⁱ	72.43 (4)	O5^vii—Fe1—O2^viii	90.5 (2)
O6—Ag1—O3ⁱ	107.57 (4)	O2^v—Fe1—O2^viii	83.31 (18)
O3ⁱⁱ—Ag1—O3ⁱ	63.13 (5)	O5^ix—Co2—O5	149.23 (7)
O3ⁱⁱⁱ—Ag1—O3ⁱ	116.87 (5)	O5^ix—Co2—O1^x	85.91 (5)
O3—Ag1—O3ⁱ	180.0	O5—Co2—O1^x	76.96 (5)
O4—Ag2—O4^iv	179.97 (6)	O5^ix—Co2—O1^xi	76.96 (5)
O4—Ag2—O4^v	87.12 (4)	O5—Co2—O1^xi	85.91 (5)
O4^iv—Ag2—O4^v	92.89 (4)	O1^x—Co2—O1^xi	111.91 (7)
O4—Ag2—O4^vi	92.89 (4)	O5^ix—Co2—O3^xii	96.48 (5)
O4^iv—Ag2—O4^vi	87.12 (4)	O5—Co2—O3^xii	107.40 (5)
O4^v—Ag2—O4^vi	169.99 (6)	O1^x—Co2—O3^xii	162.94 (5)
O6—Co1—O1ⁱⁱ	105.6 (2)	O1^xi—Co2—O3^xii	85.03 (5)
O6—Co1—O4	90.1 (2)	O5^ix—Co2—O3^v	107.40 (5)
O1ⁱⁱ—Co1—O4	89.02 (19)	O5—Co2—O3^v	96.48 (5)
O6—Co1—O5^vii	170.0 (3)	O1^x—Co2—O3^v	85.03 (5)
O1ⁱⁱ—Co1—O5^vii	79.4 (2)	O1^xi—Co2—O3^v	162.94 (5)
O4—Co1—O5^vii	98.73 (19)	O3^xii—Co2—O3^v	78.12 (7)
O6—Co1—O2^v	90.4 (2)	O3—V1—O4	112.11 (6)
O1ⁱⁱ—Co1—O2^v	161.7 (3)	O3—V1—O2	105.86 (6)
O4—Co1—O2^v	99.9 (2)	O4—V1—O2	110.50 (6)
O5^vii—Co1—O2^v	83.40 (18)	O3—V1—O1	108.79 (6)
O6—Co1—O2^viii	81.15 (16)	O4—V1—O1	107.01 (6)
O1ⁱⁱ—Co1—O2^viii	90.9 (2)	O2—V1—O1	112.65 (6)
O4—Co1—O2^viii	170.8 (3)	O6—V2—O6ⁱⁱⁱ	102.86 (8)
O5^vii—Co1—O2^viii	90.3 (2)	O6—V2—O5ⁱⁱⁱ	108.27 (6)
O2^v—Co1—O2^viii	82.90 (17)	O6ⁱⁱⁱ—V2—O5ⁱⁱⁱ	109.38 (6)
O6—Fe1—O4	89.8 (2)	O6—V2—O5	109.37 (6)
O6—Fe1—O1ⁱⁱ	105.0 (2)	O6ⁱⁱⁱ—V2—O5	108.27 (6)
O4—Fe1—O1ⁱⁱ	88.6 (2)	O5ⁱⁱⁱ—V2—O5	117.68 (8)

Symmetry codes: (i) −x, −y+1, −z; (ii) x, −y+1, z−1/2; (iii) −x, y, −z+1/2; (iv) −x+1, y, −z+3/2; (v) x, −y+1, z+1/2; (vi) −x+1, −y+1, −z+1; (vii) −x+1/2, −y+3/2, −z+1; (viii) −x+1/2, y+1/2, −z+1/2; (ix) −x, y, −z+3/2; (x) −x+1/2, y+1/2, −z+3/2; (xi) x−1/2, y+1/2, z; (xii) −x, −y+1, −z+1.

Acknowledgements

This work was done with the support of CNRST in the Excellence Research Scholarships Program. The authors thank the Unit of Support for Technical and Scientific Research (UATRS, CNRST) for the X-ray measurements and Mohammed V University in Rabat, Morocco, for the financial support.

References

Assani, A., Saadi, M., Zriouil, M. & El Ammari, L. (2011). Acta Cryst. E67, i5. Web of Science CrossRef IUCr Journals Google Scholar
Benhsina, E., Assani, A., Saadi, M. & El Ammari, L. (2016). Acta Cryst. E72, 220–222. CSD CrossRef IUCr Journals Google Scholar
Bouraima, A., Assani, A., Saadi, M., Makani, T. & El Ammari, L. (2015). Acta Cryst. E71, 558–560. Web of Science CSD CrossRef IUCr Journals Google Scholar
Brandenburg, K. (2006). DIAMOND. Crystal Impact GbR, Bonn, Germany. Google Scholar
Brown, I. D. & Altermatt, D. (1985). Acta Cryst. B41, 244–247. CrossRef CAS Web of Science IUCr Journals Google Scholar
Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Dwibedi, D., Araujo, R. B., Chakraborty, S., Shanbogh, P. P., Sundaram, N. G., Ahuja, R. & Barpanda, P. (2015). J. Mater. Chem. A, 3, 18564–18571. CrossRef CAS Google Scholar
Dwibedi, D., Ling, C. D., Araujo, R. B., Chakraborty, S., Duraisamy, S., Munichandraiah, N., Ahuja, R. & Barpanda, P. (2016). Appl. Mater. Interfaces, 8, 6982–6991. CrossRef CAS Google Scholar
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854. Web of Science CrossRef CAS IUCr Journals Google Scholar
Khmiyas, J., Assani, A., Saadi, M. & El Ammari, L. (2015). Acta Cryst. E71, 690–692. Web of Science CSD CrossRef IUCr Journals Google Scholar
Kim, J., Kim, H., Park, K.-Y., Park, Y.-U., Lee, S., Kwon, H.-S., Yoo, H.-I. & Kang, K. (2014). J. Mater. Chem. A, 2, 8632–8636. Web of Science CrossRef CAS Google Scholar
Moore, P. B. (1971). Am. Mineral. 56, 1955–1975. CAS Google Scholar
Ould Saleck, A., Assani, A., Saadi, M., Mercier, C., Follet, C. & El Ammari, L. (2015). Acta Cryst. E71, 813–815. Web of Science CSD CrossRef IUCr Journals Google Scholar
Padhi, A. K., Nanjundaswamy, K. S. & Goodenough, J. B. (1997a). J. Electrochem. Soc. 144, 1188–1194. CrossRef CAS Google Scholar
Padhi, A. K., Nanjundaswamy, K. S., Masquelier, C., Okada, S. & Goodenough, J. B. (1997b). J. Electrochem. Soc. 144, 1609–1613. CrossRef CAS Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Warner, T. E., Milius, W. & Maier, J. (1993). J. Solid State Chem. 106, 301–309. CrossRef CAS Web of Science Google Scholar
Warner, T. E., Milius, W. & Maier, J. (1994). Solid State Ionics, 74, 119–123. CrossRef CAS Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar
Yakubovich, O. V., Simonov, M. A., Egorov-Tismenko, Yu. K. & belov, N. V. (1977). Sov. Phys. Dokl. 22, 550–552. Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.