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The title compound, caesium aluminium dimolybdate(VI), CsAl(MoO4)2, belongs to the glaserite type family of double molybdates and tungstates. The crystal structure was studied by in situ X-ray single-crystal and powder diffraction at room temperature. The temperature dependence of the lattice parameters at low temperatures is also presented.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536802020950/br6069sup1.cif
Contains datablocks Tomaszewski-bis, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536802020950/br6069Isup2.hkl
Contains datablock I

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](Al-O) = 0.002 Å
  • R factor = 0.015
  • wR factor = 0.043
  • Data-to-parameter ratio = 13.8

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes

FORMU_01 There is a discrepancy between the atom counts in the _chemical_formula_sum and _chemical_formula_moiety. This is usually due to the moiety formula being in the wrong format. Atom count from _chemical_formula_sum: Al1 Cs1 Mo2 O8 Atom count from _chemical_formula_moiety:Al1 Cs1 Mo1 O4

Comment top

Double molybdates and tungstates with the general formula MIMIII(MVIO4)2, where MI = alkali metal, MIII = Al, In, Cr, Bi, Fe, RE (rare earths) and MVI = Mo or W, exhibit interesting structural and physicochemical properties and are used as acousto-optic filters, second-harmonic generators and laser crystals. They exhibit ferroelectric, ferroelastic or even ferromagnetic properties and have been extensively studied for the last 40 years. CsAl(MoO4)2 belongs to this family.

The room temperature phase of CsAl(MoO4)2 was refined in the trigonal space group P3m1 (No. 164), as for many other double molybdates and tungstates of glaserite structure (Efremov et al., 1971, Klevtsov et al., 1972, Klevtsova & Klevtsov, 1970, Klevtsova et al., 1995, Lii et al., 1989, Tomaszewski et al. 2002). The structure consists of [AlMo2O8]n layers perpendicular to the trigonal c axis, with the caesium cations between the layers. Each layer is built up from MoO4 tetrahedra and AlO6 octahedra sharing its six corners with six MoO4 tetrahedra.

The supplementary low-temperature experiments do not show any changes in the powder-diffraction diagram, thus indicating no symmetry changes and the absence of a phase transition. The low-temperature lattice parameters are as follows: a = 5.525 (2), c = 7.966 (3) Å at 110 K and a = 5.513 (3), c = 7.954 (4) Å at 40 K. The lattice parameter a changes linearly with the temperature, while the temperature dependence of the parameter c is quadratic.

Experimental top

Single crystals of CsAl(MoO4)2, were grown by cooling of a molten mixture containing CsAl(MoO4)2 and solvent (Cs2Mo2O7) in a 1:1 ratio. The cooling rate was 2 °K/h. The hexagonal single crystals obtained were colourless and of good optical quality.

Refinement top

Complementary studies on thermal dependence of lattice parameters were performed on a Siemens D5000 diffractometer working in θθ Bragg-Brentano geometry with Cu Kα radiation. The powder diagrams were recorded at temperatures 295, 110 and 40 K in a 2θ range of 10–55°, with a step size of 0.02°. The temperature was set and stabilized by an Anton Paar circulated-gaseous-helium low-temperature attachment.

Computing details top

Data collection: KM-4 CCD Software (Kuma, 1998); cell refinement: KM-4 CCD Software; data reduction: KM4CCD Data Reduction Software (Kuma, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 1991); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures top
[Figure 1] Fig. 1. View of CsAl(MoO4)2, nearly down the c axis
caesium aluminium bimolybdate(VI) top
Crystal data top
CsAl(MoO4)2Dx = 3.715 Mg m3
Mr = 479.77Mo Kα radiation, λ = 0.71073 Å
Trigonal, P3m1Cell parameters from all reflections
Hall symbol: -P 3 2"θ = 4.2–29.0°
a = 5.551 (1) ŵ = 7.21 mm1
c = 8.037 (2) ÅT = 293 K
V = 214.47 (8) Å3Plate, colourless
Z = 10.20 × 0.20 × 0.10 mm
F(000) = 216
Data collection top
Kuma KM-4 CCD
diffractometer
249 independent reflections
Radiation source: fine-focus sealed tube248 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.045
Detector resolution: 1024x1024 with blocs 2x2 pixels mm-1θmax = 29.0°, θmin = 4.2°
CCD scansh = 75
Absorption correction: numerical
as in XEMP by Sheldrick
k = 77
Tmin = 0.068, Tmax = 0.155l = 1010
2447 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.015 w = 1/[σ2(Fo2) + (0.017P)2 + 0.220P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.043(Δ/σ)max = 0.027
S = 1.37Δρmax = 0.65 e Å3
249 reflectionsΔρmin = 0.36 e Å3
18 parametersExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.253 (6)
Crystal data top
CsAl(MoO4)2Z = 1
Mr = 479.77Mo Kα radiation
Trigonal, P3m1µ = 7.21 mm1
a = 5.551 (1) ÅT = 293 K
c = 8.037 (2) Å0.20 × 0.20 × 0.10 mm
V = 214.47 (8) Å3
Data collection top
Kuma KM-4 CCD
diffractometer
249 independent reflections
Absorption correction: numerical
as in XEMP by Sheldrick
248 reflections with I > 2σ(I)
Tmin = 0.068, Tmax = 0.155Rint = 0.045
2447 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.01518 parameters
wR(F2) = 0.0430 restraints
S = 1.37Δρmax = 0.65 e Å3
249 reflectionsΔρmin = 0.36 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.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cs0.00000.00000.00000.02029 (11)
Al0.00000.00000.50000.0104 (3)
Mo0.33330.66670.70401 (4)0.01026 (11)
O10.33330.66670.9182 (4)0.0213 (7)
O20.1585 (2)0.3170 (4)0.6377 (3)0.0244 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cs0.02162 (14)0.02162 (14)0.0176 (2)0.01081 (7)0.0000.000
Al0.0084 (5)0.0084 (5)0.0145 (8)0.0042 (2)0.0000.000
Mo0.00938 (13)0.00938 (13)0.0120 (2)0.00469 (6)0.0000.000
O10.0257 (11)0.0257 (11)0.0126 (14)0.0128 (6)0.0000.000
O20.0265 (8)0.0141 (9)0.0284 (9)0.0070 (5)0.0036 (4)0.0073 (8)
Geometric parameters (Å, º) top
Cs—O1i3.2716 (9)Al—O2xi1.883 (2)
Cs—O1ii3.2716 (9)Al—O2vii1.883 (2)
Cs—O1iii3.2716 (9)Al—O2xii1.883 (2)
Cs—O1iv3.2716 (9)Al—Csxiii4.0185 (10)
Cs—O1v3.2716 (9)Mo—O11.721 (4)
Cs—O1vi3.2716 (9)Mo—O2xiv1.763 (2)
Cs—O2vii3.287 (2)Mo—O21.763 (2)
Cs—O2viii3.287 (2)Mo—O2xv1.763 (2)
Cs—O2ix3.287 (2)Mo—Csxvi3.9913 (6)
Cs—O2x3.287 (2)Mo—Csxvii3.9913 (6)
Cs—O2vi3.287 (2)Mo—Csxiii3.9913 (6)
Cs—O2v3.287 (2)O1—Csxvi3.2716 (9)
Al—O21.883 (2)O1—Csxvii3.2716 (9)
Al—O2vi1.883 (2)O1—Csxiii3.2716 (9)
Al—O2ix1.883 (2)O2—Csxiii3.287 (2)
O1i—Cs—O1ii180.0O1vi—Cs—O2vi50.78 (7)
O1i—Cs—O1iii63.93 (4)O2vii—Cs—O2vi47.35 (6)
O1ii—Cs—O1iii116.07 (4)O2viii—Cs—O2vi132.65 (6)
O1i—Cs—O1iv116.07 (4)O2ix—Cs—O2vi47.35 (6)
O1ii—Cs—O1iv63.93 (4)O2x—Cs—O2vi132.65 (6)
O1iii—Cs—O1iv180.0O1i—Cs—O2v87.19 (6)
O1i—Cs—O1v63.93 (4)O1ii—Cs—O2v92.81 (6)
O1ii—Cs—O1v116.07 (4)O1iii—Cs—O2v92.81 (6)
O1iii—Cs—O1v116.07 (4)O1iv—Cs—O2v87.19 (6)
O1iv—Cs—O1v63.93 (4)O1v—Cs—O2v50.78 (7)
O1i—Cs—O1vi116.07 (4)O1vi—Cs—O2v129.22 (7)
O1ii—Cs—O1vi63.93 (4)O2vii—Cs—O2v132.65 (6)
O1iii—Cs—O1vi63.93 (4)O2viii—Cs—O2v47.35 (6)
O1iv—Cs—O1vi116.07 (4)O2ix—Cs—O2v132.65 (6)
O1v—Cs—O1vi180.0O2x—Cs—O2v47.35 (6)
O1i—Cs—O2vii92.81 (6)O2vi—Cs—O2v180.0
O1ii—Cs—O2vii87.19 (6)O2—Al—O2vi180.0
O1iii—Cs—O2vii129.22 (7)O2—Al—O2ix91.02 (10)
O1iv—Cs—O2vii50.78 (7)O2vi—Al—O2ix88.98 (10)
O1v—Cs—O2vii87.19 (6)O2—Al—O2xi88.98 (10)
O1vi—Cs—O2vii92.81 (6)O2vi—Al—O2xi91.02 (10)
O1i—Cs—O2viii87.19 (6)O2ix—Al—O2xi180.0
O1ii—Cs—O2viii92.81 (6)O2—Al—O2vii91.02 (10)
O1iii—Cs—O2viii50.78 (7)O2vi—Al—O2vii88.98 (10)
O1iv—Cs—O2viii129.22 (7)O2ix—Al—O2vii88.98 (10)
O1v—Cs—O2viii92.81 (6)O2xi—Al—O2vii91.02 (10)
O1vi—Cs—O2viii87.19 (6)O2—Al—O2xii88.98 (10)
O2vii—Cs—O2viii180.0O2vi—Al—O2xii91.02 (10)
O1i—Cs—O2ix50.78 (7)O2ix—Al—O2xii91.02 (10)
O1ii—Cs—O2ix129.22 (7)O2xi—Al—O2xii88.98 (10)
O1iii—Cs—O2ix87.19 (6)O2vii—Al—O2xii180.0
O1iv—Cs—O2ix92.81 (6)O1—Mo—O2xiv107.60 (8)
O1v—Cs—O2ix87.19 (6)O1—Mo—O2107.60 (8)
O1vi—Cs—O2ix92.81 (6)O2xiv—Mo—O2111.28 (7)
O2vii—Cs—O2ix47.35 (6)O1—Mo—O2xv107.60 (8)
O2viii—Cs—O2ix132.65 (6)O2xiv—Mo—O2xv111.28 (7)
O1i—Cs—O2x129.22 (7)O2—Mo—O2xv111.28 (7)
O1ii—Cs—O2x50.78 (7)Csxvi—Mo—Csxvii88.117 (14)
O1iii—Cs—O2x92.81 (6)Csxvi—Mo—Csxiii88.117 (14)
O1iv—Cs—O2x87.19 (6)Csxvii—Mo—Csxiii88.117 (14)
O1v—Cs—O2x92.81 (6)Mo—O1—Csxvi101.59 (6)
O1vi—Cs—O2x87.19 (6)Mo—O1—Csxvii101.59 (6)
O2vii—Cs—O2x132.65 (6)Csxvi—O1—Csxvii116.07 (4)
O2viii—Cs—O2x47.35 (6)Mo—O1—Csxiii101.59 (6)
O2ix—Cs—O2x180.0Csxvi—O1—Csxiii116.07 (4)
O1i—Cs—O2vi92.81 (6)Csxvii—O1—Csxiii116.07 (4)
O1ii—Cs—O2vi87.19 (6)Mo—O2—Al161.61 (14)
O1iii—Cs—O2vi87.19 (6)Mo—O2—Csxiii100.03 (9)
O1iv—Cs—O2vi92.81 (6)Al—O2—Csxiii98.36 (8)
O1v—Cs—O2vi129.22 (7)
Symmetry codes: (i) x, y+1, z+1; (ii) x, y1, z1; (iii) x1, y1, z1; (iv) x+1, y+1, z+1; (v) x, y, z1; (vi) x, y, z+1; (vii) y, x+y, z+1; (viii) y, xy, z1; (ix) xy, x, z+1; (x) x+y, x, z1; (xi) x+y, x, z; (xii) y, xy, z; (xiii) x, y, z+1; (xiv) x+y, x+1, z; (xv) y+1, xy+1, z; (xvi) x, y+1, z+1; (xvii) x+1, y+1, z+1.

Experimental details

Crystal data
Chemical formulaCsAl(MoO4)2
Mr479.77
Crystal system, space groupTrigonal, P3m1
Temperature (K)293
a, c (Å)5.551 (1), 8.037 (2)
V3)214.47 (8)
Z1
Radiation typeMo Kα
µ (mm1)7.21
Crystal size (mm)0.20 × 0.20 × 0.10
Data collection
DiffractometerKuma KM-4 CCD
diffractometer
Absorption correctionNumerical
as in XEMP by Sheldrick
Tmin, Tmax0.068, 0.155
No. of measured, independent and
observed [I > 2σ(I)] reflections
2447, 249, 248
Rint0.045
(sin θ/λ)max1)0.682
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.015, 0.043, 1.37
No. of reflections249
No. of parameters18
Δρmax, Δρmin (e Å3)0.65, 0.36

Computer programs: KM-4 CCD Software (Kuma, 1998), KM-4 CCD Software, KM4CCD Data Reduction Software (Kuma, 1998), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Sheldrick, 1991).

Selected geometric parameters (Å, º) top
Cs—O1i3.2716 (9)Mo—O11.721 (4)
Cs—O2ii3.287 (2)Mo—O21.763 (2)
Al—O21.883 (2)
O2—Al—O2iii88.98 (10)O2—Mo—O2iv111.28 (7)
O1—Mo—O2107.60 (8)
Symmetry codes: (i) x, y+1, z+1; (ii) x, y, z1; (iii) y, xy, z; (iv) y+1, xy+1, z.
 

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