Acta Cryst. (2008). E64, i34 [ doi:10.1107/S1600536808013925 ]
The title compound, potassium yttrium polyphosphate, KY(PO3)4, was synthesized using the flux method. The atomic arrangement consists of an infinite long-chain polyphosphate organization. Chains, with a period of four PO4 tetrahedra, run along the a-axis direction. Two other polymorphs of this phosphate are known, in space groups P21/n and C2/c.
Single crystal of KY(PO3)4 was prepared by flux method. Homogeneous solution of potassium carbonate K2CO3 (6 g) and yttrium oxide Y2O3 (0.5 g) containing a large excess of orthophosphoric acid H3PO4 (16 ml, 85% concentration) was heated in a vitreous carbon crucible at 473 K for 1 day. Then the temperature of the furnace was slowly raised to the predermined temperature in the range of 573–623 K for 7 days. Crystals were separated from the excess phosphoric acid by washing the product in boiling water.
Data collection: CAD-4 EXPRESS (Duisenberg, 1992; Macíček & Yordanov, 1992); cell refinement: CAD-4 EXPRESS (Duisenberg, 1992; Macíček & Yordanov, 1992); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2001); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).
![[Figure 1]](./br2073fig1thm.gif)
| Fig. 1. : Projection of KY(PO3)4 with anisotropic displacement parameters drawn at the 50% probability level. |
![[Figure 2]](./br2073fig2thm.gif)
| Fig. 2. : The structural arrangement of KY(PO3)4 along the b axis. |
![[Figure 3]](./br2073fig3thm.gif)
| Fig. 3. : Projection of KY(PO3)4 along the a axis, showing isolated YO8 polyhedra joined to (PO3)n chains. |
| KY(PO3)4 | F000 = 428 |
| Mr = 443.89 | Dx = 3.138 Mg m−3 |
| Monoclinic, P21 | Melting point: 760 K |
| Hall symbol: P 2yb | Mo Kα radiation λ = 0.71073 Å |
| a = 7.2244 (3) Å | Cell parameters from 25 reflections |
| b = 8.2825 (3) Å | θ = 2.6–27.5º |
| c = 7.854 (4) Å | µ = 7.40 mm−1 |
| β = 91.735 (3)º | T = 298 (2) K |
| V = 469.7 (2) Å3 | Prism, colourless |
| Z = 2 | 0.16 × 0.14 × 0.13 mm |
| Enraf–Nonius CAD-4 diffractometer | Rint = 0.081 |
| Radiation source: fine-focus sealed tube | θmax = 27.5º |
| Monochromator: graphite | θmin = 2.6º |
| T = 298(2) K | h = −7→9 |
| ω/2θ scans | k = −8→10 |
| Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | l = −8→10 |
| Tmin = 0.321, Tmax = 0.376 | 2 standard reflections |
| 3651 measured reflections | every 150 reflections |
| 2011 independent reflections | intensity decay: 2% |
| 1904 reflections with I > 2σ(I) |
| Refinement on F2 | Secondary atom site location: difference Fourier map |
| Least-squares matrix: full | w = 1/[σ2(Fo2) + (0.0908P)2] where P = (Fo2 + 2Fc2)/3 |
| R[F2 > 2σ(F2)] = 0.048 | (Δ/σ)max < 0.001 |
| wR(F2) = 0.138 | Δρmax = 1.19 e Å−3 |
| S = 1.13 | Δρmin = −2.67 e Å−3 |
| 2011 reflections | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
| 165 parameters | Extinction coefficient: 0.065 (7) |
| 1 restraint | Absolute structure: Flack (1983), with 867 Friedel pairs |
| Primary atom site location: structure-invariant direct methods | Flack parameter: 0.002 (9) |
| KY(PO3)4 | V = 469.7 (2) Å3 |
| Mr = 443.89 | Z = 2 |
| Monoclinic, P21 | Mo Kα |
| a = 7.2244 (3) Å | µ = 7.40 mm−1 |
| b = 8.2825 (3) Å | T = 298 (2) K |
| c = 7.854 (4) Å | 0.16 × 0.14 × 0.13 mm |
| β = 91.735 (3)º |
| Enraf–Nonius CAD-4 diffractometer | 1904 reflections with I > 2σ(I) |
| Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | Rint = 0.081 |
| Tmin = 0.321, Tmax = 0.376 | 2 standard reflections |
| 3651 measured reflections | every 150 reflections |
| 2011 independent reflections | intensity decay: 2% |
| R[F2 > 2σ(F2)] = 0.048 | 1 restraint |
| wR(F2) = 0.138 | Δρmax = 1.19 e Å−3 |
| S = 1.13 | Δρmin = −2.67 e Å−3 |
| 2011 reflections | Absolute structure: Flack (1983), with 867 Friedel pairs |
| 165 parameters | Flack parameter: 0.002 (9) |
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. |
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 > 2sigma(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 | ||
| Y | 0.23704 (8) | 0.75897 (9) | 0.24245 (8) | 0.0086 (3) | |
| K | 0.2703 (3) | 0.4566 (3) | −0.2812 (3) | 0.0303 (6) | |
| P1 | 0.4367 (3) | 0.3830 (2) | 0.0947 (3) | 0.0091 (4) | |
| P2 | 0.0994 (3) | 0.1755 (2) | 0.0978 (2) | 0.0086 (4) | |
| P3 | −0.0018 (3) | 0.4085 (2) | 0.3809 (2) | 0.0088 (4) | |
| P4 | 0.6161 (3) | 0.5114 (2) | 0.3992 (2) | 0.0084 (4) | |
| O1 | 0.3212 (8) | 0.5292 (7) | 0.0721 (7) | 0.0140 (12) | |
| O2 | 0.5736 (8) | 0.3558 (8) | −0.0387 (8) | 0.0184 (13) | |
| O3 | 0.3126 (7) | 0.2261 (7) | 0.1093 (8) | 0.0169 (13) | |
| O4 | 0.5360 (8) | 0.3706 (7) | 0.2789 (7) | 0.0139 (12) | |
| O5 | 0.0239 (8) | 0.2062 (7) | −0.0776 (7) | 0.0150 (12) | |
| O6 | 0.0880 (8) | 0.0105 (7) | 0.1732 (7) | 0.0163 (12) | |
| O7 | −0.0076 (8) | 0.2991 (7) | 0.2159 (8) | 0.0189 (13) | |
| O8 | 0.1660 (7) | 0.5100 (7) | 0.3846 (7) | 0.0124 (11) | |
| O9 | −0.0337 (8) | 0.3109 (7) | 0.5348 (8) | 0.0167 (12) | |
| O10 | −0.1755 (8) | 0.5225 (7) | 0.3407 (7) | 0.0121 (11) | |
| O11 | 0.5258 (8) | 0.6648 (7) | 0.3514 (7) | 0.0138 (11) | |
| O12 | 0.6118 (7) | 0.4535 (7) | 0.5773 (7) | 0.0121 (11) |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Y | 0.0092 (4) | 0.0103 (4) | 0.0067 (4) | −0.0004 (3) | 0.0048 (2) | −0.0001 (2) |
| K | 0.0180 (10) | 0.0601 (16) | 0.0129 (8) | 0.0108 (9) | 0.0031 (7) | −0.0019 (10) |
| P1 | 0.0100 (9) | 0.0098 (10) | 0.0080 (9) | −0.0003 (7) | 0.0044 (7) | −0.0004 (6) |
| P2 | 0.0084 (9) | 0.0095 (9) | 0.0082 (9) | −0.0008 (6) | 0.0034 (7) | −0.0004 (7) |
| P3 | 0.0090 (9) | 0.0107 (10) | 0.0070 (9) | −0.0009 (7) | 0.0055 (7) | 0.0003 (7) |
| P4 | 0.0086 (9) | 0.0088 (9) | 0.0081 (8) | 0.0003 (6) | 0.0032 (7) | 0.0001 (6) |
| O1 | 0.018 (3) | 0.012 (3) | 0.012 (3) | 0.001 (2) | 0.003 (2) | −0.001 (2) |
| O2 | 0.021 (3) | 0.021 (3) | 0.014 (3) | 0.007 (2) | 0.011 (2) | −0.001 (2) |
| O3 | 0.010 (3) | 0.018 (3) | 0.023 (3) | −0.003 (2) | 0.000 (2) | −0.004 (2) |
| O4 | 0.016 (3) | 0.015 (3) | 0.011 (3) | 0.001 (2) | −0.002 (2) | 0.000 (2) |
| O5 | 0.014 (3) | 0.020 (3) | 0.011 (3) | 0.004 (2) | 0.002 (2) | −0.003 (2) |
| O6 | 0.019 (3) | 0.011 (3) | 0.019 (3) | 0.003 (2) | −0.002 (2) | 0.004 (2) |
| O7 | 0.018 (3) | 0.020 (3) | 0.019 (3) | 0.003 (2) | 0.008 (2) | −0.010 (2) |
| O8 | 0.008 (3) | 0.016 (3) | 0.013 (3) | −0.004 (2) | 0.004 (2) | 0.004 (2) |
| O9 | 0.017 (3) | 0.019 (3) | 0.015 (3) | 0.003 (2) | 0.010 (2) | 0.007 (2) |
| O10 | 0.011 (3) | 0.015 (3) | 0.011 (3) | −0.002 (2) | 0.005 (2) | 0.003 (2) |
| O11 | 0.012 (3) | 0.015 (3) | 0.014 (3) | 0.003 (2) | 0.000 (2) | 0.002 (2) |
| O12 | 0.010 (2) | 0.019 (3) | 0.008 (2) | 0.005 (2) | 0.002 (2) | 0.000 (2) |
| Y—O2i | 2.282 (6) | P1—O1 | 1.479 (6) |
| Y—O5ii | 2.296 (6) | P1—O2 | 1.480 (6) |
| Y—O9iii | 2.358 (6) | P1—O3 | 1.585 (6) |
| Y—O11 | 2.363 (5) | P1—O4 | 1.599 (5) |
| Y—O12iv | 2.387 (5) | P2—O5 | 1.488 (6) |
| Y—O6v | 2.400 (6) | P2—O6 | 1.492 (6) |
| Y—O8 | 2.408 (6) | P2—O3 | 1.597 (6) |
| Y—O1 | 2.415 (6) | P2—O7 | 1.597 (6) |
| Y—Ki | 3.921 (2) | P3—O8 | 1.474 (6) |
| K—O12vi | 2.736 (6) | P3—O9 | 1.478 (6) |
| K—O8vi | 2.744 (6) | P3—O7 | 1.581 (6) |
| K—O6ii | 2.785 (6) | P3—O10 | 1.594 (6) |
| K—O1 | 2.852 (6) | P4—O11 | 1.472 (6) |
| K—O9vi | 2.859 (7) | P4—O12 | 1.480 (6) |
| K—O11vii | 2.892 (7) | P4—O10viii | 1.590 (6) |
| K—O2 | 2.979 (6) | P4—O4 | 1.598 (6) |
| K—O5 | 3.194 (6) | ||
| O2i—Y—O5ii | 99.8 (2) | O9vi—K—O11vii | 86.49 (17) |
| O2i—Y—O9iii | 148.9 (2) | O12vi—K—O2 | 66.57 (16) |
| O5ii—Y—O9iii | 86.2 (2) | O8vi—K—O2 | 146.32 (18) |
| O2i—Y—O11 | 80.1 (2) | O6ii—K—O2 | 121.50 (18) |
| O5ii—Y—O11 | 147.3 (2) | O1—K—O2 | 50.68 (17) |
| O9iii—Y—O11 | 110.8 (2) | O9vi—K—O2 | 138.0 (2) |
| O2i—Y—O12iv | 84.6 (2) | O11vii—K—O2 | 61.22 (17) |
| O5ii—Y—O12iv | 144.7 (2) | O12vi—K—O5 | 136.07 (19) |
| O9iii—Y—O12iv | 73.79 (19) | O8vi—K—O5 | 116.25 (17) |
| O11—Y—O12iv | 67.98 (19) | O6ii—K—O5 | 54.12 (17) |
| O2i—Y—O6v | 79.1 (2) | O1—K—O5 | 72.96 (18) |
| O5ii—Y—O6v | 71.5 (2) | O9vi—K—O5 | 63.10 (17) |
| O9iii—Y—O6v | 74.0 (2) | O11vii—K—O5 | 81.22 (17) |
| O11—Y—O6v | 138.9 (2) | O2—K—O5 | 84.71 (17) |
| O12iv—Y—O6v | 75.09 (19) | O1—P1—O2 | 115.3 (4) |
| O2i—Y—O8 | 140.1 (2) | O1—P1—O3 | 111.2 (3) |
| O5ii—Y—O8 | 85.16 (19) | O2—P1—O3 | 108.5 (4) |
| O9iii—Y—O8 | 70.5 (2) | O1—P1—O4 | 113.4 (3) |
| O11—Y—O8 | 75.39 (19) | O2—P1—O4 | 109.9 (3) |
| O12iv—Y—O8 | 113.77 (19) | O3—P1—O4 | 97.0 (3) |
| O6v—Y—O8 | 138.4 (2) | O5—P2—O6 | 120.0 (3) |
| O2i—Y—O1 | 73.9 (2) | O5—P2—O3 | 109.5 (3) |
| O5ii—Y—O1 | 75.7 (2) | O6—P2—O3 | 106.4 (3) |
| O9iii—Y—O1 | 136.7 (2) | O5—P2—O7 | 104.9 (3) |
| O11—Y—O1 | 72.9 (2) | O6—P2—O7 | 108.9 (4) |
| O12iv—Y—O1 | 137.92 (19) | O3—P2—O7 | 106.4 (3) |
| O6v—Y—O1 | 132.6 (2) | O8—P3—O9 | 116.4 (4) |
| O8—Y—O1 | 69.1 (2) | O8—P3—O7 | 110.1 (3) |
| O12vi—K—O8vi | 80.69 (17) | O9—P3—O7 | 110.9 (4) |
| O12vi—K—O6ii | 169.5 (2) | O8—P3—O10 | 107.9 (3) |
| O8vi—K—O6ii | 91.99 (17) | O9—P3—O10 | 110.2 (3) |
| O12vi—K—O1 | 107.81 (17) | O7—P3—O10 | 100.1 (3) |
| O8vi—K—O1 | 156.9 (2) | O11—P4—O12 | 120.0 (3) |
| O6ii—K—O1 | 76.31 (17) | O11—P4—O10viii | 107.0 (3) |
| O12vi—K—O9vi | 118.63 (18) | O12—P4—O10viii | 109.8 (3) |
| O8vi—K—O9vi | 53.15 (16) | O11—P4—O4 | 109.3 (3) |
| O6ii—K—O9vi | 60.95 (18) | O12—P4—O4 | 107.7 (3) |
| O1—K—O9vi | 130.90 (19) | O10viii—P4—O4 | 101.5 (3) |
| O12vi—K—O11vii | 56.23 (17) | P1—O3—P2 | 139.3 (4) |
| O8vi—K—O11vii | 94.54 (19) | P4—O4—P1 | 129.2 (4) |
| O6ii—K—O11vii | 132.5 (2) | P3—O7—P2 | 147.4 (4) |
| O1—K—O11vii | 108.06 (18) | P4ix—O10—P3 | 130.9 (4) |
| Symmetry codes: (i) −x+1, y+1/2, −z; (ii) −x, y+1/2, −z; (iii) −x, y+1/2, −z+1; (iv) −x+1, y+1/2, −z+1; (v) x, y+1, z; (vi) x, y, z−1; (vii) −x+1, y−1/2, −z; (viii) x+1, y, z; (ix) x−1, y, z. |
This work was supported by the Ministry of Higher Education, Scientific Research and Technology of Tunisia.
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Yttrium condensed phosphates have been considered as a crystal hosts for optical materials when doped with lanthanides, due to there high-temperature chemical stability, high yield intrinsic fluorescence and minimal trapping of excitation, rendering them attractive materials for investigations of the energy transfer phenomena and fluorescence quenching(Malinowski, 1990; Malinowski et al., 1988). The literature dealing with these compounds was rather confusing for some time, between cyclic or chain condensed phosphates, but it is currently well established that the MIY(PO3)4 compounds are polyphosphates with infinite chain and MIYP4O12 are cyclotetraphosphates (with MI= monovalent cation) (Durif, 1995). In our laboratory we have synthesized the potassium and yttrium polyphosphates to establish the solid–liquid equilibrium diagram of the KPO3–Y(PO3)3 system (Jouini et al., 2003). Three allotropic phases with the space groups P21, P21/n and C2/c were isolated and characterized. The three monoclinic allotropes are: i) KY(PO3)4 polyphosphate with the P21 space group, isostructural with KNd(PO3)4 (Hong, 1975). ii) KY(PO3)4 polyphosphate belongs to P21/n space group, and is isostructural with TlNd(PO3)4 (Palkina et al., 1977). In these two forms the phosphate anion has a chain structure. iii) The third allotropic form is KYP4O12 which crystallizes in the C2/c space group, only this structure was investigated (Hamady, 1995). This paper is devoted to the crystal structure of the first polymorph KY(PO3)4 (P21). The atomic arrangement of this srtucture is characterized by a three-dimensional framework built of (PO3)n chains that are formed by corner-sharing of PO4 tetrahedra (Figs 1,2). The chains run along the a axis , with four PO4 tetrahedra in a repeating unit. KY(PO3)4 is isostructural with KNd(PO3)4 , but not with CsLa(PO3)4 (Sun et al., 2004) although they belong to the same space group, P21. In the latter, the infinite screw (PO3)n chains are repeated after every eighth PO4 group along the b axis. The chains (two per unit cell) are joined to each other by YO8 polyhedra (Fig 3.), no O atom is shared with the adjacent YO8 polyhedra. The K atoms are in an eightfold coordination.