Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270110050535/ku3036sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270110050535/ku3036Isup2.hkl |
For related literature, see: Bennouna et al. (1995); Bregiroux et al. (2009); Cetinkol et al. (2009); Chakir et al. (2006); Ettis et al. (2003); Hagman & Kierkegaard (1968); Herbstein (2000); Horchani-Naifer & Férid (2007); Iwata et al. (2008); Kanatzidis & Poeppelmeier (2007); Naïli & Mhiri (2005); Nedic et al. (2008); Ogorodnyk et al. (2006); Orlova et al. (2005); Parreu et al. (2006); Ranmohotti et al. (2006); Shehee et al. (2005); Sljukic et al. (1969); Tordjman et al. (1974); Xiong et al. (2007); Zaripov et al. (2009); Zatovsky et al. (2007); Zhao & Li (2010); Zhao et al. (2009).
Single crystals of CsAlZr2(PO4)4 have been prepared by high-temperature reaction in air. A powder mixture of Cs2CO3 (0.8854 g), Al2O3 (0.1662 g), ZrO2 (0.4018 g) and NH4H2PO4 (3.000 g) in a Cs:Al:Zr:P molar ratio of 1.66:1:1:8 was first ground in an agate mortar and then transferred to a platinum crucible. The sample was gradually heated in air at 1173 K for 20 h. At this stage, the reagents were partially melted. After that, the intermediate product was cooled slowly to 773 K at a rate of 5 K h-1, kept at this temperature for 10 h and then quenched to room temperature. After boiling in NH3 (5%) solution, a transparent prismatic-shaped white crystal with dimensions of 0.16 × 0.10 × 0.10 mm was selected carefully from the mixture for X-ray diffraction analysis.
The orthorhombic unit-cell parameters determined by the diffractometer were a = ????Å, b = ????Å and c = ????Å [authors to supply their original cell parameters and s.u.s]. Given that the standard uncertainties (s.u. values) of unit-cell parameters calculated by the cell determination software on area-detector diffractometers are usually significantly smaller than the reproducibility of the parameters (Herbstein, 2000), the unit-cell s.u. values used in the final refinement and reported here have been set to values estimated to reflect more realistically the precision of the unit-cell parameters. The highest peak in the difference electron-density map is 0.06 Å from the Zr1 site and the deepest hole is 0.56 Å from the Cs1 site.
Data collection: CrystalClear (Rigaku, 2004); cell refinement: CrystalClear (Rigaku, 2004); data reduction: CrystalClear (Rigaku, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXL97 (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).
CsAlZr2(PO4)4 | F(000) = 1344 |
Mr = 722.21 | Dx = 3.246 Mg m−3 |
Orthorhombic, Pbcm | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2c 2b | Cell parameters from 3559 reflections |
a = 8.742 (2) Å | θ = 2.2–27.5° |
b = 9.403 (3) Å | µ = 4.41 mm−1 |
c = 17.979 (3) Å | T = 293 K |
V = 1477.9 (6) Å3 | Prism, white |
Z = 4 | 0.16 × 0.10 × 0.10 mm |
Rigaku Mercury70 CCD diffractometer | 1751 independent reflections |
Radiation source: fine-focus sealed tube | 1696 reflections with I > 2σ(I) |
Graphite Monochromator monochromator | Rint = 0.027 |
Detector resolution: 14.6306 pixels mm-1 | θmax = 27.5°, θmin = 2.3° |
ω scans | h = −10→11 |
Absorption correction: multi-scan (ABSCOR; Higashi, 1995) | k = −9→12 |
Tmin = 0.539, Tmax = 0.667 | l = −23→22 |
10513 measured reflections |
Refinement on F2 | 0 restraints |
Least-squares matrix: full | Primary atom site location: structure-invariant direct methods |
R[F2 > 2σ(F2)] = 0.028 | Secondary atom site location: difference Fourier map |
wR(F2) = 0.068 | w = 1/[σ2(Fo2) + (0.0309P)2 + 5.7964P] where P = (Fo2 + 2Fc2)/3 |
S = 1.15 | (Δ/σ)max = 0.001 |
1751 reflections | Δρmax = 0.49 e Å−3 |
117 parameters | Δρmin = −1.79 e Å−3 |
CsAlZr2(PO4)4 | V = 1477.9 (6) Å3 |
Mr = 722.21 | Z = 4 |
Orthorhombic, Pbcm | Mo Kα radiation |
a = 8.742 (2) Å | µ = 4.41 mm−1 |
b = 9.403 (3) Å | T = 293 K |
c = 17.979 (3) Å | 0.16 × 0.10 × 0.10 mm |
Rigaku Mercury70 CCD diffractometer | 1751 independent reflections |
Absorption correction: multi-scan (ABSCOR; Higashi, 1995) | 1696 reflections with I > 2σ(I) |
Tmin = 0.539, Tmax = 0.667 | Rint = 0.027 |
10513 measured reflections |
R[F2 > 2σ(F2)] = 0.028 | 117 parameters |
wR(F2) = 0.068 | 0 restraints |
S = 1.15 | Δρmax = 0.49 e Å−3 |
1751 reflections | Δρmin = −1.79 e Å−3 |
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. |
x | y | z | Uiso*/Ueq | ||
Cs1 | 0.34872 (5) | 0.75153 (4) | 0.7500 | 0.02454 (12) | |
Zr1 | 0.24879 (4) | 0.46864 (3) | 0.928485 (18) | 0.00506 (10) | |
P1 | 0.09892 (14) | 0.42270 (13) | 0.7500 | 0.0066 (2) | |
Al1 | 0.79989 (17) | 0.60136 (15) | 0.7500 | 0.0063 (3) | |
O1 | 0.1042 (5) | 0.2611 (4) | 0.7500 | 0.0169 (8) | |
P2 | 0.03635 (13) | 0.7500 | 1.0000 | 0.0053 (2) | |
O2 | −0.0711 (4) | 0.4619 (4) | 0.7500 | 0.0171 (8) | |
P3 | 0.60769 (10) | 0.62612 (9) | 0.89837 (5) | 0.00688 (18) | |
O3 | 0.1770 (3) | 0.4834 (3) | 0.81800 (15) | 0.0164 (6) | |
O4 | 0.0641 (3) | 0.3407 (3) | 0.94850 (16) | 0.0159 (6) | |
O5 | 0.1357 (3) | 0.6526 (3) | 0.95246 (16) | 0.0147 (6) | |
O6 | 0.4391 (3) | 0.5871 (3) | 0.89610 (15) | 0.0132 (5) | |
O7 | 0.6852 (3) | 0.5524 (3) | 0.96277 (15) | 0.0163 (6) | |
O8 | 0.6245 (3) | 0.7866 (3) | 0.90189 (17) | 0.0177 (6) | |
O9 | 0.6802 (3) | 0.5740 (3) | 0.82518 (15) | 0.0170 (6) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cs1 | 0.0319 (2) | 0.01503 (19) | 0.0267 (2) | 0.00488 (14) | 0.000 | 0.000 |
Zr1 | 0.00625 (17) | 0.00477 (17) | 0.00416 (17) | −0.00025 (10) | −0.00008 (11) | 0.00026 (11) |
P1 | 0.0068 (6) | 0.0074 (6) | 0.0054 (6) | 0.0013 (4) | 0.000 | 0.000 |
Al1 | 0.0066 (7) | 0.0066 (7) | 0.0057 (7) | 0.0002 (5) | 0.000 | 0.000 |
O1 | 0.020 (2) | 0.0068 (17) | 0.024 (2) | 0.0052 (15) | 0.000 | 0.000 |
P2 | 0.0055 (5) | 0.0032 (5) | 0.0071 (6) | 0.000 | 0.000 | −0.0009 (4) |
O2 | 0.0092 (18) | 0.0111 (18) | 0.031 (2) | 0.0026 (14) | 0.000 | 0.000 |
P3 | 0.0088 (4) | 0.0074 (4) | 0.0044 (4) | −0.0022 (3) | 0.0001 (3) | 0.0003 (3) |
O3 | 0.0211 (14) | 0.0217 (15) | 0.0064 (12) | −0.0059 (11) | −0.0046 (11) | 0.0001 (11) |
O4 | 0.0128 (13) | 0.0167 (13) | 0.0181 (14) | −0.0080 (10) | 0.0013 (11) | 0.0017 (11) |
O5 | 0.0172 (14) | 0.0106 (13) | 0.0163 (13) | 0.0055 (10) | −0.0004 (11) | −0.0030 (10) |
O6 | 0.0101 (12) | 0.0138 (13) | 0.0158 (13) | −0.0042 (10) | 0.0007 (10) | 0.0016 (10) |
O7 | 0.0179 (14) | 0.0214 (14) | 0.0097 (13) | 0.0009 (11) | −0.0044 (11) | 0.0024 (11) |
O8 | 0.0168 (14) | 0.0101 (13) | 0.0261 (16) | −0.0058 (10) | −0.0033 (12) | −0.0006 (11) |
O9 | 0.0225 (14) | 0.0201 (14) | 0.0085 (12) | −0.0031 (11) | 0.0073 (11) | −0.0043 (11) |
Cs1—O2i | 3.131 (4) | P1—O2 | 1.531 (4) |
Cs1—O6 | 3.149 (3) | Al1—O1iii | 1.720 (4) |
Cs1—O6ii | 3.149 (3) | Al1—O9ii | 1.729 (3) |
Cs1—O3ii | 3.178 (3) | Al1—O9 | 1.729 (3) |
Cs1—O3 | 3.178 (3) | Al1—O2vii | 1.729 (4) |
Cs1—O9iii | 3.330 (3) | O1—Al1vi | 1.720 (4) |
Cs1—O9iv | 3.330 (3) | P2—O5viii | 1.525 (3) |
Cs1—O9 | 3.607 (3) | P2—O5 | 1.525 (3) |
Cs1—O9ii | 3.607 (3) | P2—O4i | 1.535 (3) |
Cs1—O8ii | 3.657 (3) | P2—O4ix | 1.535 (3) |
Cs1—O8 | 3.658 (3) | O2—Al1x | 1.729 (4) |
Zr1—O5 | 2.038 (3) | O2—Cs1xi | 3.131 (4) |
Zr1—O4 | 2.045 (3) | P3—O7 | 1.510 (3) |
Zr1—O7v | 2.048 (3) | P3—O8 | 1.517 (3) |
Zr1—O6 | 2.085 (3) | P3—O6 | 1.519 (3) |
Zr1—O3 | 2.088 (3) | P3—O9 | 1.540 (3) |
Zr1—O8vi | 2.095 (3) | O4—P2ix | 1.535 (3) |
P1—O3 | 1.512 (3) | O7—Zr1v | 2.048 (3) |
P1—O3ii | 1.512 (3) | O8—Zr1iii | 2.095 (3) |
P1—O1 | 1.520 (4) | O9—Cs1vi | 3.330 (3) |
O2i—Cs1—O6 | 120.31 (5) | O7v—Zr1—O6 | 95.35 (11) |
O2i—Cs1—O6ii | 120.31 (5) | O5—Zr1—O3 | 89.94 (11) |
O6—Cs1—O6ii | 113.07 (10) | O4—Zr1—O3 | 88.25 (11) |
O2i—Cs1—O3ii | 97.77 (9) | O7v—Zr1—O3 | 177.97 (11) |
O6—Cs1—O3ii | 92.87 (7) | O6—Zr1—O3 | 86.47 (11) |
O6ii—Cs1—O3ii | 53.71 (7) | O5—Zr1—O8vi | 176.76 (11) |
O2i—Cs1—O3 | 97.77 (9) | O4—Zr1—O8vi | 88.67 (11) |
O6—Cs1—O3 | 53.72 (7) | O7v—Zr1—O8vi | 89.43 (12) |
O6ii—Cs1—O3 | 92.86 (7) | O6—Zr1—O8vi | 87.19 (11) |
O3ii—Cs1—O3 | 45.24 (10) | O3—Zr1—O8vi | 89.78 (12) |
O2i—Cs1—O9iii | 50.63 (8) | O3—P1—O3ii | 107.9 (2) |
O6—Cs1—O9iii | 97.33 (7) | O3—P1—O1 | 111.33 (14) |
O6ii—Cs1—O9iii | 143.60 (7) | O3ii—P1—O1 | 111.33 (14) |
O3ii—Cs1—O9iii | 147.42 (7) | O3—P1—O2 | 110.32 (14) |
O3—Cs1—O9iii | 122.03 (7) | O3ii—P1—O2 | 110.32 (14) |
O2i—Cs1—O9iv | 50.63 (8) | O1—P1—O2 | 105.7 (2) |
O6—Cs1—O9iv | 143.60 (7) | O1iii—Al1—O9ii | 115.13 (13) |
O6ii—Cs1—O9iv | 97.33 (7) | O1iii—Al1—O9 | 115.13 (13) |
O3ii—Cs1—O9iv | 122.03 (7) | O9ii—Al1—O9 | 102.9 (2) |
O3—Cs1—O9iv | 147.42 (7) | O1iii—Al1—O2vii | 110.1 (2) |
O9iii—Cs1—O9iv | 47.90 (10) | O9ii—Al1—O2vii | 106.39 (13) |
O2i—Cs1—O9 | 156.22 (5) | O9—Al1—O2vii | 106.39 (13) |
O6—Cs1—O9 | 42.14 (6) | P1—O1—Al1vi | 152.6 (3) |
O6ii—Cs1—O9 | 83.33 (7) | O5viii—P2—O5 | 110.5 (2) |
O3ii—Cs1—O9 | 99.01 (7) | O5viii—P2—O4i | 109.30 (15) |
O3—Cs1—O9 | 82.43 (7) | O5—P2—O4i | 108.76 (15) |
O9iii—Cs1—O9 | 109.28 (6) | O5viii—P2—O4ix | 108.76 (15) |
O9iv—Cs1—O9 | 129.38 (6) | O5—P2—O4ix | 109.30 (15) |
O2i—Cs1—O9ii | 156.22 (5) | O4i—P2—O4ix | 110.2 (2) |
O6—Cs1—O9ii | 83.33 (7) | P1—O2—Al1x | 144.6 (3) |
O6ii—Cs1—O9ii | 42.14 (6) | P1—O2—Cs1xi | 126.88 (19) |
O3ii—Cs1—O9ii | 82.43 (7) | Al1x—O2—Cs1xi | 88.48 (15) |
O3—Cs1—O9ii | 99.01 (7) | O7—P3—O8 | 112.40 (17) |
O9iii—Cs1—O9ii | 129.38 (6) | O7—P3—O6 | 110.18 (16) |
O9iv—Cs1—O9ii | 109.28 (6) | O8—P3—O6 | 109.57 (16) |
O9—Cs1—O9ii | 44.02 (8) | O7—P3—O9 | 108.93 (16) |
O2i—Cs1—O8ii | 117.00 (6) | O8—P3—O9 | 108.18 (17) |
O6—Cs1—O8ii | 120.11 (7) | O6—P3—O9 | 107.42 (16) |
O6ii—Cs1—O8ii | 41.92 (6) | O7—P3—Cs1 | 167.35 (12) |
O3ii—Cs1—O8ii | 95.48 (7) | O8—P3—Cs1 | 76.81 (11) |
O3—Cs1—O8ii | 132.06 (7) | O6—P3—Cs1 | 57.51 (10) |
O9iii—Cs1—O8ii | 105.73 (7) | O9—P3—Cs1 | 74.73 (12) |
O9iv—Cs1—O8ii | 70.42 (6) | P1—O3—Zr1 | 151.60 (18) |
O9—Cs1—O8ii | 77.99 (6) | P1—O3—Cs1 | 101.64 (13) |
O9ii—Cs1—O8ii | 39.86 (6) | Zr1—O3—Cs1 | 106.08 (10) |
O2i—Cs1—O8 | 117.00 (6) | P2ix—O4—Zr1 | 152.20 (18) |
O6—Cs1—O8 | 41.92 (6) | P2—O5—Zr1 | 154.79 (18) |
O6ii—Cs1—O8 | 120.11 (7) | P3—O6—Zr1 | 153.56 (17) |
O3ii—Cs1—O8 | 132.06 (7) | P3—O6—Cs1 | 98.47 (12) |
O3—Cs1—O8 | 95.48 (7) | Zr1—O6—Cs1 | 107.16 (10) |
O9iii—Cs1—O8 | 70.42 (6) | P3—O7—Zr1v | 154.52 (19) |
O9iv—Cs1—O8 | 105.73 (7) | P3—O8—Zr1iii | 150.87 (18) |
O9—Cs1—O8 | 39.86 (6) | P3—O8—Cs1 | 79.37 (11) |
O9ii—Cs1—O8 | 77.99 (6) | Zr1iii—O8—Cs1 | 126.35 (11) |
O8ii—Cs1—O8 | 96.60 (9) | P3—O9—Al1 | 150.4 (2) |
O5—Zr1—O4 | 94.54 (11) | P3—O9—Cs1vi | 127.23 (14) |
O5—Zr1—O7v | 90.96 (11) | Al1—O9—Cs1vi | 82.17 (11) |
O4—Zr1—O7v | 89.87 (11) | P3—O9—Cs1 | 80.94 (12) |
O5—Zr1—O6 | 89.58 (11) | Al1—O9—Cs1 | 97.16 (12) |
O4—Zr1—O6 | 173.30 (11) | Cs1vi—O9—Cs1 | 102.02 (7) |
Symmetry codes: (i) −x, y+1/2, z; (ii) x, y, −z+3/2; (iii) −x+1, y+1/2, z; (iv) −x+1, y+1/2, −z+3/2; (v) −x+1, −y+1, −z+2; (vi) −x+1, y−1/2, z; (vii) x+1, y, z; (viii) x, −y+3/2, −z+2; (ix) −x, −y+1, −z+2; (x) x−1, y, z; (xi) −x, y−1/2, z. |
Experimental details
Crystal data | |
Chemical formula | CsAlZr2(PO4)4 |
Mr | 722.21 |
Crystal system, space group | Orthorhombic, Pbcm |
Temperature (K) | 293 |
a, b, c (Å) | 8.742 (2), 9.403 (3), 17.979 (3) |
V (Å3) | 1477.9 (6) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 4.41 |
Crystal size (mm) | 0.16 × 0.10 × 0.10 |
Data collection | |
Diffractometer | Rigaku Mercury70 CCD diffractometer |
Absorption correction | Multi-scan (ABSCOR; Higashi, 1995) |
Tmin, Tmax | 0.539, 0.667 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 10513, 1751, 1696 |
Rint | 0.027 |
(sin θ/λ)max (Å−1) | 0.649 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.028, 0.068, 1.15 |
No. of reflections | 1751 |
No. of parameters | 117 |
Δρmax, Δρmin (e Å−3) | 0.49, −1.79 |
Computer programs: CrystalClear (Rigaku, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).
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Anhydrous inorganic metal phosphates prepared by high-temperature solid-state reactions have been part [the focus?] of intensive research activities and their number has grown steadily (Kanatzidis et al., 2007; Ettis et al., 2003;Zaripov et al., 2009; Zatovsky et al., 2007; Xiong et al., 2007; Ranmohotti et al., 2006; Parreu et al., 2006). The crystal chemistry of these compounds with partial structures mainly built from PO4 tetrahedral building units reveals a large structural variety, which is usually accompanied by intriguing magnetism, electric, optical and thermal expansion properties. Furthermore, chemical and thermal stability ensures their wide application in many fields. Introduction of MIV (M = Ti, Zr, Ge, Sn) cations into the phosphates can form [result in?] many different three-dimensional frameworks with the basic unit of MO6 octahedra and PO4 tetrahedra, such as KTiPO5 (Tordjman et al., 1974) and NaZr2(PO4)3 (Hagman et al., 1968). As for ZrIV metal, the reported phosphates include KZr2(PO4)3 (Sljukic et al., 1969), K4CeZr(PO4)4 (Ogorodnyk, et al., 2006), Na3AZr(PO4)3 (A = Mg, Ni; Chakir et al., 2006), A2Mg0.5Zr1.5(PO4)3 (A = K, Rb, Cs; Orlova et al., 2005) and NaNbZr(PO4)3 (Bennouna et al., 1995) etc. We expected that introduction of AlO4 groups which may serve as bridges between ZrO6 and PO4 building units would result in new zirconium phosphate compounds with novel architectures. Our research efforts in this regard have led to a novel caesium aluminium zirconium phosphate compound, namely, CsAlZr2(PO4)4. To the best of our knowledge, it represents the first compound in the quinary Cs/Al/Zr/P/O system.
The title compound, CsAlZr2(PO4)4, crystallizes in the orthorhombic space group Pbcm, with 15 crystallographically independent atoms, viz. one Cs, one Al, one Zr, three P and nine O atoms. Fig. 1 illustrates a selected unit of the compound, which highlights that the Zr atom is six-coordinated by O atoms in an octahedral geometry. The Zr—O bond distances are in the range 2.038 (3)–2.095 (3) Å, with a mean value of 2.067 (3) Å, which is in good agreement with those found in other zirconium(IV) compounds, such as BaZr(PO4)2 (Bregiroux et al., 2009), Zr2(MoO4)(PO4)2 (Cetinkol et al., 2009) and Rb2Zr(IO3)6 (Shehee et al., 2005). The P and Al atoms all have the four-coordinated geometry with O atoms. The P—O distances fall in the range 1.510 (3)–1.540 (3) Å, and the O—P—O angles range from 105.7 (2) to 112.40 (17)°, which is comparable to those reported in other metal phosphates (Ettis et al., 2003; Zhao et al., 2010). The Al—O bond distances fall in the range 1.720 (4)–1.729 (4) Å, and the O—Al—O bond angles range from 102.9 (2) to 115.13 (13)°, which is similar to those reported in other aluminium(III) compounds, such as Ca12Al14O32Cl2 (Iwata et al., 2008) and Sr(Al2Si2O8) (Nedic et al., 2008).
The structure of CsAlZr2(PO4)4 features a complicated three-dimensional framework of [AlZr2(PO4)4] constructed by interconnected PO4, AlO4 and ZrO6 polyhedra. Fig. 2 shows the polyhedral connectivity of them. All PO4 tetrahedra are isolated from each other, and they are linked to adjacent polyhedra only by corner-sharing O atoms. The P1O4 tetrahedron is coordinated by two Al1O4 and two Zr1O6 polyhedra; the P2O4 tetrahedron is coordinated by four Zr1O6 octahedra; P3O4 is coordinated by one Al1O4 tetrahedron and three Zr1O6 octahedra. As for the connection of ZrO6 polyhedra, the Zr1O6 polyhedron is coordinated by six PO4 tetrahedra, that is, three P3O4, two P2O4 and one P1O4 polyhedra. On the other hand, AlO4 tetrahedra are also isolated from each other: four corners are shared with two P1O4 and two P3O4 polyhedra. It is notable that all nine asymmetric O atoms are all in bicoordinate bridging mode. As in all the above-mentioned groups, AlO4, ZrO6 and PO4 are interconnected via corner-sharing O atoms to form the three-dimensional framework of [AlZr2(PO4)4].
Furthermore, the framework [AlZr2(PO4)4] delimits infinite tunnels along the c axis in which the Cs atoms are located through coulombic action of Cs+ cations and O2- anions to form the final structure of CsAlZr2(PO4)4. It is interesting to note that the Cs atoms are in linear array with the adjacent Cs···Cs distance 8.9897 (6) Å. Considering the coordination of Cs atoms, they have an 11-fold coordination of O atoms, which come from six two AlO4, four ZrO6 and six PO4 groups, as shown in Fig. 3. The Cs—O bond distances range from 3.131 (4) to 3.658 (3) Å. Compounds containing 11-coordinated-geometry Cs atoms have been reported in the literature, for example CsPr(PO3)4 (Horchani-Naifer & Férid, 2007), CsGd(PO3)4 (Naïli & Mhiri, 2005) and Cs2GeP4O13 (Zhao et al., 2009).
Finally, the structure can be checked by bond-valence-sum (BVS) analysis (Brese & O'Keeffe, 1991). The calculated total BVS for Cs1, Al1, Zr1, P1, P2 and P3 are 1.005, 3.260, 4.236, 5.038, 4.886 and 5.001, respectively, which show the oxidation states of Cs, Al, Zr and P are +1, +3, +4 and +5, respectively.