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Single crystals of lithium iron tungstate, LiFe(WO4)2, were obtained using a high-temperature solution growth method. The analysis was conducted using the monoclinic space group C2/c, with β = 90.597 (2)°, giving R1 = 0.0177. The Li and Fe atoms lie on twofold axes. The structure can also be refined using the ortho­rhom­bic space group Cmcm, giving slightly higher residuals. The experimental value of β and the residuals mitigate in favour of the monoclinic description of the structure. Calculated bond-valence sums for the present results are closer to expected values than those obtained using the results of a previously reported analysis of this structure.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270111053832/fa3264sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270111053832/fa3264Isup2.hkl
Contains datablock I

Comment top

Cation distributions in the A+B3+(WO4)2 compounds of the wolframite structure [(Fe,Mn)WO4] have been studied by Le Flem et al. (1969, 1970) and Salmon et al. (1970). The analyses performed on this family of compounds, known as `double tungstates', showed that the distribution of cations in the wolframite structure depends on their relative sizes. Indeed, both homogeneous chains, encompassing a unique cation, and chains with alternating cations are encountered. Among these materials, LiFe(WO4)2 was previously obtained as single crystals and its structure was refined to R = 0.149 (Klevtsova & Belov, 1970; Klevtsov & Klevtsova, 1970; Klevtsov et al., 1971).

When the previously reported structure of LiFe(WO4)2 is analysed using the bond-valence model (Brese & O'Keeffe, 1991), some inconsistencies arise regarding the iron–tungsten network. Though values of the oxygen and lithium valences are in good agreement with the expected values, the average cationic bond-valence sums (BVS) calculated for Fe and W are considerably different from what is expected, viz. νFe = 3.90 and νW = 5.32 (Table 1). A possible explanation of these results could involve partial disorder of the iron and tungsten cations over their six-coordinate sites in the octahedral framework. Such a statistical Fe/W distribution between two distinct B sites is actually observed in perovskites with composition A3Fe2WO9 and A = Sr (Viola et al., 2003), A = Ca (Ivanov et al., 2005) and Ba (Ivanov et al., 2006). But the structural model presented by Klevtsov et al. (1971) does not indicate any disorder. So, one could speculate that the refined structure was idealized while the real sample was not perfectly ordered.

It is worth mentioning that our description of the LiFe(WO4)2 crystal structure could appear, at a first glance, compatible with higher symmetry, namely with the orthorhombic space group Cmcm (No. 63). However, the value of the cell angle β [90.597 (2)°] cannot be assigned as 90° within experimental error. Furthermore, the refinement using Cmcm yields poorer values of the reliability factors: R1 = 0.0362 and wR2 = 0.1488 for Cmcm compared to R1 = 0.017 and wR2 = 0.0413 for C2/c. The orthorhombic model requires disorder of the O atoms, which is neither required nor observed in the C2/c model. Further, refinement with Cmcm gives unreasonable displacement parameters and is not, in any event, compatible with the observed lithium iron tungstate, LiFe(WO4)2, unit-cell angle β. The Li, Fe and W atoms, as refined with the space group C2/c, do adhere quite well to Cmcm symmetry, and the O atoms are the only ones that clearly require the lower-symmetry description.

According to the bond-valence analysis of the results of our refinement (Tables 2 and 3), the structure of LiFe(WO4)2 displays full order as far as the Fe and W ions are concerned. This time the values of the BVS calculation for all ions are in very good agreement with the theoretical ones.

LiFe(WO4)2 is based on a distorted hexagonal packing of O atoms and is closely related to the wolframite structure. The structure is built of two kind of chains of edge-sharing octahedra, which are propagated along [010] (Fig. 1). The first type of chain contains Li+ and Fe3+ ions (both on twofold axes, Wyckoff sites 4e, formula [Li0.5Fe0.5O4]6-). The second chain is composed of tungstate units on general positions (formula [WO4]2-). The overall structure is the union of these two types of chains by corner sharing. All cations have octahedral coordination with bond lengths (Table 3) very close to the values expected on the basis of ionic radii (Shannon, 1976).

No structural data have been reported for LiFe(WO4)2 since 1970, although a recent work on positive electrode materials for rechargeable lithium batteries (Li & Fu, 2008) reported the electrochemical characterization of LiFe(WO4)2. Our present structural study of this double tungstate provides a more accurate description of its crystal structure than has been available up to now.

Related literature top

Brese & O'Keeffe (1991); Klevtsova & Belov (1970); Le Flem, Salmon & Hagenmuller (1969, 1970); Li & Fu (2008); Salmon et al. (1970); Shannon (1976); Viola et al. (2003).

Experimental top

Monoclinic crystals of LiFe(WO4)2 were obtained using a classical high-temperature solution growth procedure (Elwell & Scheel, 1975), in an attempt to grow an iron tungstate using LiBO2 as solvent. During this experiment, the flux reacted with the iron tungstate to form LiFe(WO4)2.

Computing details top

Data collection: COLLECT (Bruker, 2008); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg 1999); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. (a) The octahedral layers of Li, Fe and W in the crystal structure of LiFeW2O8, viewed along [100], and (b) a representation of the alternating zigzag cation chains.
lithium iron tungstate top
Crystal data top
LiFe(WO4)2F(000) = 964
Mr = 558.46Dx = 7.136 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 6452 reflections
a = 9.2884 (3) Åθ = 2.9–32.0°
b = 11.4181 (3) ŵ = 46.90 mm1
c = 4.9018 (1) ÅT = 293 K
β = 90.597 (2)°Needle, yellow
V = 519.84 (2) Å30.15 × 0.03 × 0.02 mm
Z = 4
Data collection top
Nonius KappaCCD
diffractometer
906 independent reflections
Radiation source: Enraf Nonius FR590, fine-focus sealed X-ray tube827 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.081
ϕ scans, and ω scansθmax = 32.0°, θmin = 3.6°
Absorption correction: gaussian
a grid of 8 x 8 x 52 = 3328 sampling points
h = 1313
Tmin = 0.090, Tmax = 0.630k = 1616
11306 measured reflectionsl = 77
Refinement top
Refinement on F20 restraints
Least-squares matrix: full w = 1/[σ2(Fo2) + (0.0165P)2 + 1.2747P]
where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.018(Δ/σ)max = 0.002
wR(F2) = 0.041Δρmax = 1.67 e Å3
S = 1.12Δρmin = 2.57 e Å3
906 reflectionsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
57 parametersExtinction coefficient: 0.0091 (2)
Crystal data top
LiFe(WO4)2V = 519.84 (2) Å3
Mr = 558.46Z = 4
Monoclinic, C2/cMo Kα radiation
a = 9.2884 (3) ŵ = 46.90 mm1
b = 11.4181 (3) ÅT = 293 K
c = 4.9018 (1) Å0.15 × 0.03 × 0.02 mm
β = 90.597 (2)°
Data collection top
Nonius KappaCCD
diffractometer
906 independent reflections
Absorption correction: gaussian
a grid of 8 x 8 x 52 = 3328 sampling points
827 reflections with I > 2σ(I)
Tmin = 0.090, Tmax = 0.630Rint = 0.081
11306 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.01857 parameters
wR(F2) = 0.0410 restraints
S = 1.12Δρmax = 1.67 e Å3
906 reflectionsΔρmin = 2.57 e Å3
Special details top

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

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Li10.50.3428 (7)0.250.011 (2)
Fe10.50.16523 (6)0.750.00640 (17)
W10.247439 (12)0.091398 (11)0.24612 (2)0.00444 (8)
O10.3633 (3)0.0591 (2)0.9242 (5)0.0065 (4)
O20.3805 (3)0.1822 (3)0.4110 (5)0.0077 (5)
O30.1449 (3)0.0483 (2)0.5542 (5)0.0064 (5)
O40.1226 (3)0.1942 (2)0.1080 (5)0.0072 (5)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Li10.009 (5)0.020 (6)0.003 (4)00.001 (4)0
Fe10.0062 (4)0.0063 (4)0.0066 (4)00.0002 (3)0
W10.00575 (10)0.00383 (10)0.00374 (11)0.00030 (4)0.00002 (6)0.00011 (3)
O10.0076 (11)0.0054 (10)0.0066 (11)0.0012 (9)0.0006 (9)0.0004 (9)
O20.0082 (12)0.0077 (10)0.0070 (11)0.0002 (10)0.0011 (9)0.0003 (9)
O30.0073 (11)0.0059 (11)0.0061 (11)0.0005 (9)0.0000 (9)0.0008 (8)
O40.0075 (11)0.0066 (11)0.0075 (11)0.0008 (9)0.0006 (9)0.0003 (9)
Geometric parameters (Å, º) top
Li1—O3i2.075 (6)O1—O2v2.873 (4)
Li1—O4ii2.124 (3)O2—O2iv2.738 (5)
Li1—O4iii2.124 (3)O2—O4vi2.748 (3)
Li1—O22.288 (7)O2—O1viii2.760 (3)
Li1—O2iv2.288 (7)O2—O32.766 (4)
Fe1—O11.958 (3)O2—O1vii2.773 (4)
Fe1—O1v1.958 (3)O2—O42.808 (5)
Fe1—O21.998 (3)O2—O4iii2.817 (5)
Fe1—O2v1.998 (3)O2—O1v2.873 (4)
Fe1—O4vi2.091 (3)O3—Li1vi2.075 (6)
Fe1—O4iii2.091 (3)O3—W1x2.078 (3)
W1—O41.779 (3)O3—O1viii2.460 (4)
W1—O21.799 (3)O3—O3viii2.688 (2)
W1—O31.860 (2)O3—O3x2.688 (2)
W1—O1vii1.954 (2)O3—O42.756 (4)
W1—O3viii2.078 (3)O3—O4x2.790 (3)
W1—O1viii2.203 (3)O3—O3xi2.953 (5)
O1—W1ix1.954 (2)O3—O4xii3.089 (4)
O1—W1x2.203 (3)O4—Fe1vi2.091 (3)
O1—O3x2.460 (4)O4—Li1ii2.124 (3)
O1—O32.710 (4)O4—O4xii2.682 (5)
O1—O2x2.760 (3)O4—O2vi2.748 (3)
O1—O2ix2.773 (4)O4—O3viii2.790 (3)
O1—O1viii2.798 (3)O4—O2xiii2.817 (5)
O1—O1x2.798 (3)O4—O1vi2.824 (3)
O1—O4vi2.824 (3)O4—O1vii2.869 (4)
O1—O4ix2.869 (4)O4—O4ii2.897 (5)
O3vi—Li1—O3i106.4 (4)O3—O2—O4iii145.17 (15)
O3vi—Li1—O4ii99.00 (15)O1vii—O2—O4iii125.97 (14)
O3i—Li1—O4ii94.71 (14)O4—O2—O4iii146.12 (11)
O3vi—Li1—O4iii94.71 (14)W1—O2—O1v114.04 (15)
O3i—Li1—O4iii99.00 (15)Li1—O2—O1v94.91 (14)
O4ii—Li1—O4iii157.0 (5)O2iv—O2—O1v59.17 (10)
O3vi—Li1—O290.05 (11)O4vi—O2—O1v91.50 (9)
O3i—Li1—O2163.5 (3)O1viii—O2—O1v63.43 (12)
O4ii—Li1—O282.4 (2)O3—O2—O1v108.26 (13)
O4iii—Li1—O279.2 (2)O1vii—O2—O1v91.93 (13)
O3vi—Li1—O2iv163.5 (3)O4—O2—O1v150.68 (12)
O3i—Li1—O2iv90.05 (11)O4iii—O2—O1v59.51 (10)
O4ii—Li1—O2iv79.2 (2)W1—O2—O193.84 (12)
O4iii—Li1—O2iv82.4 (2)Li1—O2—O1136.22 (13)
O2—Li1—O2iv73.5 (3)O2iv—O2—O1123.69 (14)
O1—Fe1—O1v103.50 (16)O4vi—O2—O160.09 (8)
O1—Fe1—O293.76 (11)O1viii—O2—O159.33 (8)
O1v—Fe1—O293.13 (11)O3—O2—O157.23 (10)
O1—Fe1—O2v93.13 (11)O1vii—O2—O1119.97 (15)
O1v—Fe1—O2v93.76 (11)O4—O2—O1115.47 (13)
O2—Fe1—O2v168.85 (17)O4iii—O2—O189.80 (11)
O1—Fe1—O4vi88.39 (10)O1v—O2—O164.53 (11)
O1v—Fe1—O4vi168.01 (12)W1—O3—Li1vi123.9 (2)
O2—Fe1—O4vi84.40 (10)W1—O3—W1x109.54 (12)
O2v—Fe1—O4vi87.05 (11)Li1vi—O3—W1x123.16 (17)
O1—Fe1—O4iii168.01 (12)W1—O3—O1viii59.40 (10)
O1v—Fe1—O4iii88.39 (10)Li1vi—O3—O1viii163.57 (17)
O2—Fe1—O4iii87.05 (11)W1x—O3—O1viii50.15 (9)
O2v—Fe1—O4iii84.40 (10)W1—O3—O3viii50.46 (5)
O4vi—Fe1—O4iii79.77 (15)Li1vi—O3—O3viii132.37 (8)
O4—W1—O2103.45 (15)W1x—O3—O3viii95.34 (13)
O4—W1—O398.42 (12)O1viii—O3—O3viii63.34 (11)
O2—W1—O398.20 (11)W1—O3—O3x148.62 (9)
O4—W1—O1vii100.34 (11)Li1vi—O3—O3x79.52 (14)
O2—W1—O1vii95.18 (12)O1viii—O3—O3x92.25 (13)
O3—W1—O1vii153.71 (13)O3viii—O3—O3x131.5 (2)
O4—W1—O3viii92.33 (11)W1—O3—O198.37 (13)
O2—W1—O3viii162.85 (12)Li1vi—O3—O198.51 (11)
O3—W1—O3viii85.90 (8)W1x—O3—O152.80 (8)
O1vii—W1—O3viii75.12 (11)O1viii—O3—O165.31 (11)
O4—W1—O1viii168.33 (12)O3viii—O3—O1128.44 (9)
O2—W1—O1viii86.62 (11)O3x—O3—O154.22 (8)
O3—W1—O1viii73.99 (11)Li1vi—O3—O487.79 (17)
O1vii—W1—O1viii84.36 (9)W1x—O3—O4148.62 (12)
O3viii—W1—O1viii78.48 (12)O1viii—O3—O498.69 (13)
Fe1—O1—W1ix126.89 (14)O3viii—O3—O461.65 (8)
Fe1—O1—W1x128.78 (12)O3x—O3—O4166.25 (15)
W1ix—O1—W1x101.33 (11)O1—O3—O4123.61 (12)
Fe1—O1—O3x164.12 (17)Li1vi—O3—O2107.8 (2)
W1ix—O1—O3x54.73 (9)W1x—O3—O2100.33 (11)
W1x—O1—O3x46.61 (8)O1viii—O3—O263.46 (11)
Fe1—O1—O3102.73 (11)O3viii—O3—O289.32 (8)
W1ix—O1—O397.71 (13)O3x—O3—O2117.77 (8)
W1x—O1—O348.72 (7)O1—O3—O263.65 (10)
O3x—O1—O362.44 (10)O4—O3—O261.15 (11)
Fe1—O1—O2x124.74 (13)W1—O3—O4x112.22 (11)
W1ix—O1—O2x103.88 (11)Li1vi—O3—O4x120.1 (2)
O3x—O1—O2x63.67 (11)O1viii—O3—O4x65.91 (11)
O3—O1—O2x88.98 (9)O3viii—O3—O4x71.28 (12)
Fe1—O1—O2ix91.70 (11)O3x—O3—O4x60.37 (12)
W1x—O1—O2ix139.47 (12)O1—O3—O4x92.15 (9)
O3x—O1—O2ix94.02 (12)O4—O3—O4x132.06 (12)
O3—O1—O2ix129.41 (13)O2—O3—O4x129.23 (11)
O2x—O1—O2ix121.57 (13)W1—O3—O3xi115.23 (14)
Fe1—O1—O1viii84.86 (7)Li1vi—O3—O3xi73.29 (17)
W1ix—O1—O1viii143.46 (10)W1x—O3—O3xi101.95 (13)
O3x—O1—O1viii89.66 (14)O1viii—O3—O3xi121.31 (17)
O3—O1—O1viii53.03 (8)O3viii—O3—O3xi72.00 (10)
O2x—O1—O1viii59.85 (12)O3x—O3—O3xi90.11 (12)
O2ix—O1—O1viii176.29 (10)O1—O3—O3xi144.31 (16)
Fe1—O1—O1x133.36 (8)O4—O3—O3xi91.27 (12)
W1ix—O1—O1x51.59 (5)O2—O3—O3xi152.03 (15)
W1x—O1—O1x88.09 (13)O4x—O3—O3xi65.00 (11)
O3x—O1—O1x61.65 (11)W1—O3—O4xii93.77 (10)
O3—O1—O1x123.90 (9)W1x—O3—O4xii153.40 (13)
O2x—O1—O1x62.60 (12)O1viii—O3—O4xii149.95 (14)
O2ix—O1—O1x59.41 (7)O3viii—O3—O4xii89.68 (7)
O1viii—O1—O1x122.35 (19)O3x—O3—O4xii116.65 (8)
Fe1—O1—O4vi47.74 (8)O1—O3—O4xii137.95 (11)
W1ix—O1—O4vi83.28 (11)O4—O3—O4xii54.27 (11)
W1x—O1—O4vi141.11 (12)O2—O3—O4xii105.85 (12)
O3x—O1—O4vi123.40 (15)O4x—O3—O4xii119.96 (11)
O3—O1—O4vi92.43 (9)O3xi—O3—O4xii54.95 (9)
O2x—O1—O4vi172.46 (14)W1—O4—Fe1vi137.28 (14)
O2ix—O1—O4vi62.61 (9)W1—O4—Li1ii121.6 (2)
O1viii—O1—O4vi115.56 (11)Fe1vi—O4—Li1ii98.0 (2)
O1x—O1—O4vi122.02 (12)W1—O4—O4xii110.85 (13)
Fe1—O1—O4ix108.35 (13)Fe1vi—O4—O4xii50.12 (8)
W1x—O1—O4ix99.49 (11)Li1ii—O4—O4xii88.74 (13)
O3x—O1—O4ix62.58 (10)W1—O4—O2vi91.42 (10)
O3—O1—O4ix69.76 (10)Fe1vi—O4—O2vi46.36 (9)
O2x—O1—O4ix126.12 (11)Li1ii—O4—O2vi143.19 (18)
O2ix—O1—O4ix59.68 (11)O4xii—O4—O2vi62.49 (10)
O1viii—O1—O4ix122.78 (8)Fe1vi—O4—O3103.66 (11)
O1x—O1—O4ix88.70 (7)Li1ii—O4—O3124.8 (2)
O4vi—O1—O4ix61.17 (11)O4xii—O4—O369.21 (10)
W1ix—O1—O2v98.18 (11)O2vi—O4—O368.32 (8)
W1x—O1—O2v153.25 (14)W1—O4—O3viii48.10 (8)
O3x—O1—O2v148.67 (15)Fe1vi—O4—O3viii146.55 (14)
O3—O1—O2v145.33 (12)Li1ii—O4—O3viii76.4 (2)
O2x—O1—O2v116.57 (12)O4xii—O4—O3viii96.51 (8)
O2ix—O1—O2v57.99 (11)O2vi—O4—O3viii126.30 (13)
O1viii—O1—O2v118.34 (7)O3—O4—O3viii57.98 (8)
O1x—O1—O2v89.85 (7)Fe1vi—O4—O2109.01 (11)
O4vi—O1—O2v59.26 (10)Li1ii—O4—O2150.94 (18)
O4ix—O1—O2v107.13 (13)O4xii—O4—O2116.71 (17)
W1—O2—Fe1133.70 (15)O2vi—O4—O265.64 (10)
W1—O2—Li1129.83 (13)O3—O4—O259.60 (9)
Fe1—O2—Li195.58 (11)O3viii—O4—O286.43 (9)
W1—O2—O2iv107.36 (13)W1—O4—O2xiii167.37 (18)
Fe1—O2—O2iv91.86 (14)Fe1vi—O4—O2xiii45.10 (8)
Li1—O2—O2iv53.26 (14)Li1ii—O4—O2xiii52.95 (19)
W1—O2—O4vi131.95 (12)O4xii—O4—O2xiii59.90 (11)
Fe1—O2—O4vi49.24 (7)O2vi—O4—O2xiii91.23 (14)
Li1—O2—O4vi83.92 (15)O3—O4—O2xiii128.89 (14)
O2iv—O2—O4vi120.70 (12)O3viii—O4—O2xiii121.64 (14)
W1—O2—O1viii52.81 (9)O2—O4—O2xiii151.53 (11)
Fe1—O2—O1viii85.14 (11)W1—O4—O1vi130.47 (14)
Li1—O2—O1viii146.74 (18)Li1ii—O4—O1vi100.2 (2)
O2iv—O2—O1viii93.49 (8)O4xii—O4—O1vi93.96 (7)
O4vi—O2—O1viii119.42 (12)O2vi—O4—O1vi62.41 (11)
Fe1—O2—O399.76 (12)O3—O4—O1vi130.10 (12)
Li1—O2—O3156.70 (17)O3viii—O4—O1vi168.89 (13)
O2iv—O2—O3142.64 (10)O2—O4—O1vi92.21 (9)
O4vi—O2—O392.91 (9)O2xiii—O4—O1vi61.23 (10)
O1viii—O2—O352.87 (10)Fe1vi—O4—O1vii161.09 (14)
Fe1—O2—O1vii133.85 (15)Li1ii—O4—O1vii92.66 (16)
Li1—O2—O1vii97.66 (13)O4xii—O4—O1vii146.27 (9)
O2iv—O2—O1vii62.84 (10)O2vi—O4—O1vii124.09 (10)
O4vi—O2—O1vii176.09 (11)O3—O4—O1vii82.63 (11)
O1viii—O2—O1vii60.74 (9)O3viii—O4—O1vii51.51 (9)
O3—O2—O1vii84.23 (11)O2—O4—O1vii58.46 (9)
Fe1—O2—O4155.23 (16)O2xiii—O4—O1vii141.61 (14)
Li1—O2—O4101.10 (11)O1vi—O4—O1vii118.83 (11)
O2iv—O2—O4112.78 (16)W1—O4—O4ii84.13 (13)
O4vi—O2—O4114.36 (10)Fe1vi—O4—O4ii103.53 (15)
O1viii—O2—O490.69 (9)Li1ii—O4—O4ii102.63 (16)
O3—O2—O459.25 (10)O4xii—O4—O4ii152.99 (11)
O1vii—O2—O461.87 (9)O2vi—O4—O4ii95.94 (14)
W1—O2—O4iii170.09 (18)O3—O4—O4ii120.05 (15)
Fe1—O2—O4iii47.85 (8)O3viii—O4—O4ii109.89 (14)
Li1—O2—O4iii47.81 (8)O2—O4—O4ii61.28 (11)
O2iv—O2—O4iii63.13 (11)O2xiii—O4—O4ii107.87 (17)
O4vi—O2—O4iii57.61 (12)O1vi—O4—O4ii60.18 (11)
O1viii—O2—O4iii122.54 (14)O1vii—O4—O4ii58.65 (10)
Symmetry codes: (i) x+1/2, y+1/2, z1/2; (ii) x+1/2, y+1/2, z; (iii) x+1/2, y+1/2, z+1/2; (iv) x+1, y, z+1/2; (v) x+1, y, z+3/2; (vi) x+1/2, y+1/2, z+1; (vii) x, y, z1; (viii) x, y, z1/2; (ix) x, y, z+1; (x) x, y, z+1/2; (xi) x, y, z+1; (xii) x, y, z+1/2; (xiii) x1/2, y+1/2, z1/2.

Experimental details

Crystal data
Chemical formulaLiFe(WO4)2
Mr558.46
Crystal system, space groupMonoclinic, C2/c
Temperature (K)293
a, b, c (Å)9.2884 (3), 11.4181 (3), 4.9018 (1)
β (°) 90.597 (2)
V3)519.84 (2)
Z4
Radiation typeMo Kα
µ (mm1)46.90
Crystal size (mm)0.15 × 0.03 × 0.02
Data collection
DiffractometerNonius KappaCCD
diffractometer
Absorption correctionGaussian
a grid of 8 x 8 x 52 = 3328 sampling points
Tmin, Tmax0.090, 0.630
No. of measured, independent and
observed [I > 2σ(I)] reflections
11306, 906, 827
Rint0.081
(sin θ/λ)max1)0.745
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.018, 0.041, 1.12
No. of reflections906
No. of parameters57
Δρmax, Δρmin (e Å3)1.67, 2.57

Computer programs: COLLECT (Bruker, 2008), DENZO and SCALEPACK (Otwinowski & Minor, 1997), SIR92 (Altomare et al., 1994), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg 1999), WinGX (Farrugia, 1999).

Table 1. Bond-valence analysis using interatomic distances reported by Klevtsov & Klevtsova (1970). top
AtomLi1Fe1W1V(O)
O12 × 0.830.741.88
0.31
O22 × 0.162 × 0.681.151.99
O32 × 0.181.031.88
0.67
O42 × 0.182 × 0.441.422.04
V(cation)1.033.905.32
Table 2. Bond-valence parameters derived from the present refinement. top
AtomLi1Fe1W1V(O)
O12 × 0.5840.915(O1iv)1.966
0.467(O1v)
O22 × 0.1082 × 0.5241.3912.023
O32 × 0.1931.1792.026
0.654(O3v)
O42 × 0.1692 × 0.4081.4682.045
V(cation)0.943.0326.073
Symmetry codes: (i) x+1/2, -y+1/2, z-1/2; (ii) -x+1/2, -y+1/2, -z; (iii) -x+1/2, -y+1/2, -z+1; (iv) x, y, z-1; (v) x, -y, z-1/2.
Table 3. Interatomic distances (Å) from the present analysis of LiFe(WO4)2. The shortest M···M and O···O distances are also listed. top
The dcalc values are sums of ionic radii as given by Shannon (1976).
Atoms i,jdijAtoms i,jdij
Li1—O3i,O3iii2.075 (6)Fe1—O1,O1viii1.958 (3)
Li1—O4ii,O4vi2.124 (3)Fe1—O2,O2viii1.998 (3)
Li1—O2,O2vii2.288 (7)Fe1—O4iii,O4vi2.091 (3)
<Li—O>2.163 (5)<Fe—O>2.016 (3)
dcalc(Li+—O2-)2.14dcalc(Fe3+—O2-)2.045
W1—O41.779 (3)
W1—O21.799 (3)Fe1···Li13.181 (5)
W1—O31.860 (3)W1···W1v3.219 (1)
W1—O1iv1.954 (3)Li1···W1ii3.405 (9)
W1—O3v2.078 (3)O1···O3ix2.460 (4)
W1—O1v2.203 (3)
<W—O>1.946 (3)
dcalc(W6+—O2-)1.98
Symmetry codes: (i) x+1/2, -y+1/2, z-1/2; (ii) -x+1/2, -y+1/2, -z; (iii) -x+1/2, -y+1/2, -z+1; (iv) x, y, z-1; (v) x, -y, z-1/2; (vi) x+1/2, -y+1/2, z+1/2; (vii) 1-x, y, -z+1/2; (viii) 1-x, y, -z+3/2; (ix) x, -y, z+1/2.
 

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