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Acta Crystallogr Sect E Struct Rep Online. 2009 August 1; 65(Pt 8): i58.
Published online 2009 July 4. doi:  10.1107/S1600536809025434
PMCID: PMC2977501

CsMgPO4

Abstract

Caesium magnesium orthophosphate is built up from MgO4 and PO4 tetra­hedra (both with . m. symmetry) linked together by corners, forming a three-dimensional framework. The Cs atoms have .m. site symmetry and are located in hexa­gonal channels running along the a- and b-axis directions.

Related literature

For the properties of double phosphates A I B IIPO4 (A I = alkali metal; B II = Ca, Sr, Ba, Zn, Cd, Pb) such as ferroelectric and non-linear optical behaviour, see: Blum et al. (1984 [triangle]); Elouadi et al. (1984 [triangle]); Sawada et al. (2003 [triangle]). Several polymorphs have been found among orthophosphates containing Cs and divalent metals, see: Blum et al. (1986 [triangle]) for CsZnPO4. In contrast, CsMnPO4 occurs in only one type, see: Yakubovich et al. (1990 [triangle]). The title compound is isotypic with the Pnma form of CsZnPO4. For related structures, see: Yakubovich et al. (1990 [triangle]); Blum et al. (1986 [triangle]); Zaripov et al. (2008 [triangle]).

Experimental

Crystal data

  • CsMgPO4
  • M r = 252.19
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-65-00i58-efi1.jpg
  • a = 8.9327 (2) Å
  • b = 5.5277 (2) Å
  • c = 9.6487 (3) Å
  • V = 476.43 (3) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 8.13 mm−1
  • T = 293 K
  • 0.12 × 0.10 × 0.08 mm

Data collection

  • Oxford Diffraction Xcalibur-3 diffractometer
  • Absorption correction: multi-scan (Blessing, 1995 [triangle]) T min = 0.413, T max = 0.503
  • 8753 measured reflections
  • 1137 independent reflections
  • 874 reflections with I > 2σ(I)
  • R int = 0.027

Refinement

  • R[F 2 > 2σ(F 2)] = 0.021
  • wR(F 2) = 0.047
  • S = 1.00
  • 1137 reflections
  • 41 parameters
  • Δρmax = 1.23 e Å−3
  • Δρmin = −1.02 e Å−3

Data collection: CrysAlis CCD (Oxford Diffraction, 2006 [triangle]); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2006 [triangle]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: DIAMOND (Brandenburg, 1999 [triangle]); software used to prepare material for publication: WinGX (Farrugia, 1999 [triangle]) and enCIFer (Allen et al., 2004 [triangle]).

Table 1
Selected bond lengths (Å)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809025434/mg2075sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809025434/mg2075Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

The authors acknowledge the ICDD for financial support (grant No. 03–02).

supplementary crystallographic information

Comment

Double phosphates AIBIIPO4 (AI = alkali metal; BII = Ca, Sr, Ba, Zn, Cd, Pb) exhibit important properties such as ferroelectric and nonlinear optical behaviour (Blum et al., 1984; Elouadi et al., 1984; Sawada et al., 2003). Among some orthophosphates containing Cs and divalent metals, several polymorphs have been found. For instance, CsZnPO4 occurs in a monoclinic (space group P21/a) and two orthorhombic types (space groups Pna21 and Pnma) (Blum et al., 1986). In contrast, CsMnPO4 occurs in only one type (space group Pna21) (Yakubovich et al., 1990). CsMgPO4, reported here, is isotypic with the Pnma form of CsZnPO4.

Except for O2 (8d), all atoms are in special positions (4c) (Fig. 1). Each MgO4 tetrahedron is linked with four PO4 tetrahedra via common vertices, resulting in a three-dimensional framework with two types of hexagonal channels, filled by Cs atoms, along the a and b directions (Fig. 2). With a cut-off distance of 3.7 Å, the Cs atoms are 11-coordinate. In general, the principles of crystal structure building are equivalent to those in CsMIIPO4 (MII = Mn, Zn) (Yakubovich et al., 1990; Blum et al., 1986) and CsLi0.5Al0.5PO4 (Zapirov et al., 2008).

Experimental

In the course of investigating the Cs2O–MgO–Bi2O3–P2O5 system, the starting components CsPO3 (3.0 g), MgO (0.113 g) and Bi2O3 (0.652 g) were finely ground and melted in a platinum crucible at 1273 K. The melt was kept at this temperature over 2 h to reach homogeneity and then cooled at a rate of 30 K h-1 to 993 K. After the melt was cooled to room temperature and treated with a small amount of deionized water, colorless needle-shaped crystals were isolated. X-ray powder diffraction showed that CsMgPO4 is the only crystalline product.

Refinement

The deepest hole and the highest peak are 0.67 Å and 0.65 Å, respectively, from Cs1.

Figures

Fig. 1.
View of CsMgPO4 with displacement ellipsoids at the 50% probability level.
Fig. 2.
Formation of hexagonal channels along a and b directions in CsMgPO4 (PO4, pink; MgO4, yellow; Cs, blue).

Crystal data

CsMgPO4F(000) = 456
Mr = 252.19Dx = 3.516 Mg m3
Orthorhombic, PnmaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2nCell parameters from 8753 reflections
a = 8.9327 (2) Åθ = 3.1–35.0°
b = 5.5277 (2) ŵ = 8.13 mm1
c = 9.6487 (3) ÅT = 293 K
V = 476.43 (3) Å3Prism, colorless
Z = 40.12 × 0.10 × 0.08 mm

Data collection

Oxford Diffraction Xcalibur-3 diffractometer1137 independent reflections
Radiation source: fine-focus sealed tube874 reflections with I > 2σ(I)
graphiteRint = 0.027
[var phi] and ω scansθmax = 35.0°, θmin = 3.1°
Absorption correction: multi-scan (Blessing, 1995)h = −14→14
Tmin = 0.413, Tmax = 0.503k = −8→8
8753 measured reflectionsl = −15→15

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.021w = 1/[σ2(Fo2) + (0.0265P)2] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.047(Δ/σ)max = 0.018
S = 1.00Δρmax = 1.23 e Å3
1137 reflectionsΔρmin = −1.02 e Å3
41 parametersExtinction correction: SHELXL97 (Sheldrick, 2008)
0 restraintsExtinction coefficient: 0.0211 (4)

Special details

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)

xyzUiso*/Ueq
Cs10.497176 (11)0.250.703332 (10)0.02472 (2)
Mg10.32166 (5)0.250.08109 (5)0.01434 (11)
P10.20302 (4)0.250.41474 (4)0.01345 (7)
O10.26034 (19)0.250.26799 (13)0.0590 (6)
O20.26291 (11)0.02604 (13)0.48850 (9)0.0328 (2)
O30.03356 (14)0.250.41501 (19)0.0345 (4)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Cs10.02161 (4)0.02632 (5)0.02623 (4)0−0.00031 (4)0
Mg10.01301 (19)0.0133 (2)0.0168 (2)00.00166 (17)0
P10.01272 (13)0.01259 (14)0.01505 (14)00.00207 (12)0
O10.0594 (11)0.1014 (17)0.0162 (7)00.0121 (7)0
O20.0239 (4)0.0190 (4)0.0555 (6)−0.0002 (3)−0.0016 (4)0.0156 (4)
O30.0121 (4)0.0286 (6)0.0629 (10)0−0.0003 (6)0

Geometric parameters (Å, °)

Cs1—O23.1951 (9)Mg1—Cs1xiii4.1402 (4)
Cs1—O2i3.1951 (9)P1—O11.5056 (13)
Cs1—O2ii3.2166 (9)P1—O31.5138 (13)
Cs1—O2iii3.2166 (9)P1—O2i1.5249 (8)
Cs1—O3iv3.4476 (11)P1—O21.5249 (8)
Cs1—O3v3.4476 (11)P1—Cs1ix3.8727 (3)
Cs1—O1vi3.5224 (11)P1—Cs1xiii3.8727 (3)
Cs1—O1ii3.5224 (11)P1—Cs1vi4.0136 (3)
Cs1—O1v3.6496 (11)P1—Cs1ii4.0136 (3)
Cs1—O1iv3.6496 (11)P1—Cs1xiv4.1184 (4)
Cs1—O3vii3.6968 (18)O1—Cs1vi3.5224 (11)
Cs1—Mg1vi3.8189 (4)O1—Cs1ii3.5224 (11)
Mg1—O11.8847 (13)O1—Cs1ix3.6496 (11)
Mg1—O3viii1.8932 (13)O1—Cs1xiii3.6496 (11)
Mg1—O2ix1.9228 (8)O2—Mg1v1.9228 (8)
Mg1—O2x1.9228 (8)O2—Cs1ii3.2166 (9)
Mg1—Cs1vi3.8189 (4)O3—Mg1xii1.8932 (13)
Mg1—Cs1ii3.8189 (4)O3—Cs1ix3.4476 (11)
Mg1—Cs1xi3.9678 (5)O3—Cs1xiii3.4476 (11)
Mg1—Cs1xii3.9916 (5)O3—Cs1xiv3.6968 (18)
Mg1—Cs1ix4.1402 (4)
O2—Cs1—O2i45.59 (3)O1—Mg1—Cs1ix61.80 (3)
O2—Cs1—O2ii83.06 (3)O3viii—Mg1—Cs1ix133.01 (2)
O2i—Cs1—O2ii104.291 (19)O2ix—Mg1—Cs1ix48.11 (3)
O2—Cs1—O2iii104.291 (19)O2x—Mg1—Cs1ix113.07 (3)
O2i—Cs1—O2iii83.06 (3)Cs1vi—Mg1—Cs1ix128.277 (13)
O2ii—Cs1—O2iii56.64 (3)Cs1ii—Mg1—Cs1ix69.709 (5)
O2—Cs1—O3iv130.00 (3)Cs1xi—Mg1—Cs1ix122.243 (9)
O2i—Cs1—O3iv91.24 (3)Cs1xii—Mg1—Cs1ix72.323 (7)
O2ii—Cs1—O3iv140.73 (3)O1—Mg1—Cs1xiii61.80 (3)
O2iii—Cs1—O3iv90.78 (3)O3viii—Mg1—Cs1xiii133.01 (2)
O2—Cs1—O3v91.24 (3)O2ix—Mg1—Cs1xiii113.07 (3)
O2i—Cs1—O3v130.00 (3)O2x—Mg1—Cs1xiii48.11 (3)
O2ii—Cs1—O3v90.78 (3)Cs1vi—Mg1—Cs1xiii69.709 (5)
O2iii—Cs1—O3v140.73 (3)Cs1ii—Mg1—Cs1xiii128.277 (14)
O3iv—Cs1—O3v106.58 (5)Cs1xi—Mg1—Cs1xiii122.243 (9)
O2—Cs1—O1vi139.27 (2)Cs1xii—Mg1—Cs1xiii72.323 (7)
O2i—Cs1—O1vi98.61 (3)Cs1ix—Mg1—Cs1xiii83.758 (9)
O2ii—Cs1—O1vi90.44 (3)O1—P1—O3109.98 (10)
O2iii—Cs1—O1vi42.55 (2)O1—P1—O2i108.64 (5)
O3iv—Cs1—O1vi51.20 (3)O3—P1—O2i110.49 (5)
O3v—Cs1—O1vi129.16 (3)O1—P1—O2108.64 (5)
O2—Cs1—O1ii98.61 (3)O3—P1—O2110.49 (5)
O2i—Cs1—O1ii139.27 (2)O2i—P1—O2108.56 (7)
O2ii—Cs1—O1ii42.55 (2)O1—P1—Cs1116.78 (7)
O2iii—Cs1—O1ii90.44 (3)O3—P1—Cs1133.24 (7)
O3iv—Cs1—O1ii129.16 (3)O2i—P1—Cs154.54 (3)
O3v—Cs1—O1ii51.20 (3)O2—P1—Cs154.54 (3)
O1vi—Cs1—O1ii103.38 (4)O1—P1—Cs1ix70.23 (4)
O2—Cs1—O1v53.46 (2)O3—P1—Cs1ix62.56 (4)
O2i—Cs1—O1v89.52 (3)O2i—P1—Cs1ix170.83 (4)
O2ii—Cs1—O1v99.15 (2)O2—P1—Cs1ix80.12 (3)
O2iii—Cs1—O1v151.35 (2)Cs1—P1—Cs1ix134.428 (4)
O3iv—Cs1—O1v117.11 (3)O1—P1—Cs1xiii70.23 (4)
O3v—Cs1—O1v40.66 (3)O3—P1—Cs1xiii62.56 (4)
O1vi—Cs1—O1v165.554 (5)O2i—P1—Cs1xiii80.12 (3)
O1ii—Cs1—O1v77.288 (3)O2—P1—Cs1xiii170.83 (4)
O2—Cs1—O1iv89.52 (3)Cs1—P1—Cs1xiii134.428 (4)
O2i—Cs1—O1iv53.46 (2)Cs1ix—P1—Cs1xiii91.069 (8)
O2ii—Cs1—O1iv151.35 (2)O1—P1—Cs1vi60.41 (4)
O2iii—Cs1—O1iv99.15 (2)O3—P1—Cs1vi131.89 (3)
O3iv—Cs1—O1iv40.66 (3)O2i—P1—Cs1vi48.65 (4)
O3v—Cs1—O1iv117.11 (3)O2—P1—Cs1vi117.22 (4)
O1vi—Cs1—O1iv77.288 (3)Cs1—P1—Cs1vi75.434 (6)
O1ii—Cs1—O1iv165.554 (5)Cs1ix—P1—Cs1vi130.546 (10)
O1v—Cs1—O1iv98.45 (4)Cs1xiii—P1—Cs1vi70.558 (4)
O2—Cs1—O3vii134.74 (2)O1—P1—Cs1ii60.41 (4)
O2i—Cs1—O3vii134.74 (2)O3—P1—Cs1ii131.89 (3)
O2ii—Cs1—O3vii120.97 (2)O2i—P1—Cs1ii117.22 (4)
O2iii—Cs1—O3vii120.97 (2)O2—P1—Cs1ii48.65 (4)
O3iv—Cs1—O3vii54.33 (3)Cs1—P1—Cs1ii75.434 (6)
O3v—Cs1—O3vii54.33 (3)Cs1ix—P1—Cs1ii70.558 (4)
O1vi—Cs1—O3vii82.40 (2)Cs1xiii—P1—Cs1ii130.546 (10)
O1ii—Cs1—O3vii82.40 (2)Cs1vi—P1—Cs1ii87.043 (8)
O1v—Cs1—O3vii83.40 (2)O1—P1—Cs1xiv173.36 (7)
O1iv—Cs1—O3vii83.40 (2)O3—P1—Cs1xiv63.38 (7)
O2—Cs1—Mg1vi155.689 (15)O2i—P1—Cs1xiv74.87 (4)
O2i—Cs1—Mg1vi110.517 (14)O2—P1—Cs1xiv74.87 (4)
O2ii—Cs1—Mg1vi111.987 (18)Cs1—P1—Cs1xiv69.857 (6)
O2iii—Cs1—Mg1vi71.807 (16)Cs1ix—P1—Cs1xiv105.375 (7)
O3iv—Cs1—Mg1vi29.64 (2)Cs1xiii—P1—Cs1xiv105.375 (7)
O3v—Cs1—Mg1vi106.93 (3)Cs1vi—P1—Cs1xiv123.498 (7)
O1vi—Cs1—Mg1vi29.40 (2)Cs1ii—P1—Cs1xiv123.498 (7)
O1ii—Cs1—Mg1vi105.34 (2)P1—O1—Mg1177.02 (12)
O1v—Cs1—Mg1vi136.22 (2)P1—O1—Cs1vi97.77 (4)
O1iv—Cs1—Mg1vi68.03 (2)Mg1—O1—Cs1vi84.06 (4)
O3vii—Cs1—Mg1vi54.563 (11)P1—O1—Cs1ii97.77 (4)
O1—Mg1—O3viii105.76 (8)Mg1—O1—Cs1ii84.06 (4)
O1—Mg1—O2ix109.29 (4)Cs1vi—O1—Cs1ii103.38 (4)
O3viii—Mg1—O2ix113.71 (4)P1—O1—Cs1ix86.93 (5)
O1—Mg1—O2x109.29 (4)Mg1—O1—Cs1ix91.12 (4)
O3viii—Mg1—O2x113.71 (4)Cs1vi—O1—Cs1ix174.41 (4)
O2ix—Mg1—O2x105.04 (6)Cs1ii—O1—Cs1ix78.860 (3)
O1—Mg1—Cs1vi66.55 (3)P1—O1—Cs1xiii86.93 (5)
O3viii—Mg1—Cs1vi64.25 (3)Mg1—O1—Cs1xiii91.12 (4)
O2ix—Mg1—Cs1vi173.66 (3)Cs1vi—O1—Cs1xiii78.860 (3)
O2x—Mg1—Cs1vi81.10 (3)Cs1ii—O1—Cs1xiii174.41 (4)
O1—Mg1—Cs1ii66.55 (3)Cs1ix—O1—Cs1xiii98.45 (4)
O3viii—Mg1—Cs1ii64.25 (3)P1—O2—Mg1v136.32 (7)
O2ix—Mg1—Cs1ii81.10 (3)P1—O2—Cs1102.59 (4)
O2x—Mg1—Cs1ii173.66 (3)Mg1v—O2—Cs1105.27 (4)
Cs1vi—Mg1—Cs1ii92.725 (11)P1—O2—Cs1ii110.51 (4)
O1—Mg1—Cs1xi173.62 (6)Mg1v—O2—Cs1ii98.78 (3)
O3viii—Mg1—Cs1xi67.86 (6)Cs1—O2—Cs1ii96.94 (3)
O2ix—Mg1—Cs1xi74.24 (3)P1—O3—Mg1xii178.96 (13)
O2x—Mg1—Cs1xi74.24 (3)P1—O3—Cs1ix94.51 (5)
Cs1vi—Mg1—Cs1xi109.444 (9)Mg1xii—O3—Cs1ix86.11 (4)
Cs1ii—Mg1—Cs1xi109.444 (9)P1—O3—Cs1xiii94.51 (5)
O1—Mg1—Cs1xii116.54 (5)Mg1xii—O3—Cs1xiii86.11 (4)
O3viii—Mg1—Cs1xii137.70 (6)Cs1ix—O3—Cs1xiii106.58 (5)
O2ix—Mg1—Cs1xii52.79 (3)P1—O3—Cs1xiv95.14 (8)
O2x—Mg1—Cs1xii52.79 (3)Mg1xii—O3—Cs1xiv83.82 (6)
Cs1vi—Mg1—Cs1xii133.015 (6)Cs1ix—O3—Cs1xiv125.67 (3)
Cs1ii—Mg1—Cs1xii133.015 (6)Cs1xiii—O3—Cs1xiv125.67 (3)
Cs1xi—Mg1—Cs1xii69.840 (9)

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: MG2075).

References

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