PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
 
Acta Crystallogr Sect E Struct Rep Online. Nov 1, 2010; 66(Pt 11): i76–i77.
Published online Oct 31, 2010. doi:  10.1107/S1600536810043539
PMCID: PMC3009187
α-Ba2P2O7
Driss Zakaria,a Fatima Erragh,a Abdelghani Oudahmane,b Malika El-Ghozzi,b and Daniel Avignantb*
aLaboratoire de Physico-Chimie des Matériaux, Université Chouaib Doukkali, Faculté des Sciences BP 20, 24000 El Jadida, Morocco
bUniversité Blaise Pascal, Laboratoire des Matériaux Inorganiques, UMR CNRS 6002, 24 Avenue des Landais, 63177 Aubière, France
Correspondence e-mail: daniel.avignant/at/univ-bpclermont.fr
Received October 6, 2010; Accepted October 25, 2010.
Single crystals of α-Ba2P2O7, dibarium diphosphate, were obtained by solid-state reaction. The ortho­rhom­bic structure is isotypic with α-Sr2P2O7 and is the second polymorph obtained for this composition. The structure is built from two different BaO9 polyhedra (both with m symmetry), with Ba—O distances in the ranges 2.7585 (10)–3.0850 (6) and 2.5794 (13)–2.9313 (4) Å. These polyhedra are further linked by sharing corners along [010] and either edges or triangular faces perpendicularly to [010] to form the three-dimensional framework. This polyhedral linkage delimits large channels parallel to [010] where the P2O7 diphosphate anions are located. These groups (symmetry m) are characterized by a P—O—P angle of 131.52 (9)° and an eclipsed conformation. They are connected to the BaO9 polyhedra through edges and corners.
Besides crystals of the title compound, crystals of the hexa­gonal polymorph σ-Ba2P2O7 were obtained (ElBelghitti et al. 1995 [triangle]). For isotypic structures, see: Hagman et al. (1968 [triangle]); Grenier & Masse (1977 [triangle]); Barbier & Echard (1998 [triangle]). For closely related structures, see: Elmarzouki et al. (1995 [triangle]). For polymorphism in Ba2P2O7, see: McCauley & Hummel (1968 [triangle]); Mehdi et al. (1977 [triangle]); Bian et al. (2004 [triangle]); Kokhanovskii (2004 [triangle]). For a review of the crystal chemistry of diphosphates, see: Durif (1995 [triangle]). For applications of alkaline earth diphosphates, see: Pang et al. (2009 [triangle]); Peng et al. (2010 [triangle]). For an independent refinement of the α-Ba2P2O7 structure based on data from a hydro­thermally grown crystal, see: Heyward et al. (2010 [triangle]).
Crystal data
  • Ba2P2O7
  • M r = 448.62
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-66-00i76-efi29.jpg
  • a = 9.2875 (1) Å
  • b = 5.6139 (1) Å
  • c = 13.8064 (1) Å
  • V = 719.85 (2) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 11.31 mm−1
  • T = 296 K
  • 0.26 × 0.14 × 0.14 mm
Data collection
  • Bruker APEXII CCD diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2008 [triangle]) T min = 0.155, T max = 0.205
  • 18034 measured reflections
  • 4304 independent reflections
  • 3726 reflections with I > 2σ(I)
  • R int = 0.028
Refinement
  • R[F 2 > 2σ(F 2)] = 0.021
  • wR(F 2) = 0.046
  • S = 1.07
  • 4304 reflections
  • 62 parameters
  • Δρmax = 1.59 e Å−3
  • Δρmin = −1.99 e Å−3
Data collection: APEX2 (Bruker, 2008 [triangle]); cell refinement: SAINT (Bruker, 2008 [triangle]); data reduction: SAINT; 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]) and ORTEP-3 for Windows (Farrugia, 1997 [triangle]); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 [triangle]).
Table 1
Table 1
Selected bond lengths (Å)
Supplementary Material
Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810043539/wm2413sup1.cif
Structure factors: contains datablocks I. DOI: 10.1107/S1600536810043539/wm2413Isup2.hkl
Additional supplementary materials: crystallographic information; 3D view; checkCIF report
Acknowledgments
This work was supported by the French–Moroccan integrated action (grant No. MA/05/119 F).
supplementary crystallographic information
Comment
Due to their potential applications as optical materials (Pang et al., 2009, Peng et al., 2010), alkaline earth diphosphates exhibit at the present time a growing interest. Since the optical properties are strongly related to the crystal structure, the study of polymorphism in these materials is worth investigating. Besides the hexagonal form σ-Ba2P2O7 described by ElBelghitti et al. (1995), the title compound is the second polymorph for this composition obtained in the form of single-crystals. The orthorhombic title compound α-Ba2P2O7 is isotypic with α-Sr2P2O7 (Hagman et al. 1968; Grenier & Masse, 1977; Barbier & Echard, 1998) and closely related to BaPbP2O7 (Elmarzouki et al., 1995). The existence of this polymorph has previously been mentioned by Durif (1995) and several other authors (McCauley & Hummel, 1968; Mehdi et al., 1977; Bian et al., 2004; Kokhanovskii, 2004).
The structure of the α-polymorph is built up from two different BaO9 polyhedra with Ba—O distances ranging from 2.7585 (10) Å to 3.0850 (6) Å and from 2.5794 (13) Å to 2.9313 (4) Å, respectively. Figure 1 displays details of these coordination polyhedra as well as their linkage by corners, edges or triangular faces to form the three-dimensional framework. This polyhedral linkage delimits large channels parallel to [010] where the P2O7 diphosphate groups are located (Fig. 2). These groups (symmetry m) are characterized by a P—O—P angle of 131.52 (9)° and an eclipsed conformation. They are connected to the BaO9 polyhedra through edges and corners. Each oxygen atom of the P2O7 groups, apart from the O1 bridging oxygen, is bonded to three Ba atoms and one phosphorus atom. During the anisotropic refinement of the displacement parameters of the isotypic α-Sr2P2O7 structure (Barbier & Echard, 1998), the authors observed a very strong anisotropy along the b direction for both O5 and O1 atoms located in the (010) mirror plane and interpreted this phenomenon as a possible atomic-scale disorder associated with the local loss of mirror symmetry resulting in a non-centrosymmetric structural arrangement. Such an outstanding feature is still present in our anisotropic structure refinement, although the amplitudes of the atomic displacement parameters are significantly lower, especially for the U22 component of the O5 atom. If the strong anisotropy of the O1 atom is perfectly understandable because of its bridging role, that of the O5 atom strongly bonded to two Ba1 atoms at 3.0850 (6) Å, one Ba2 atom at 2.5794 (13) Å and one P1 atom at 1.5067 (13) Å is more surprising. However, due to the relative homogeneity of the values of the isotropic displacement parameters of all oxygen atoms, it does not seem necessary to envisage any atomic-scale disorder for the O5 atom in the present case.
Simultaneous with our refinement, an independent study of the α-Ba2P2O7 structure from a hydrothermally grown crystal was reported by Heyward et al. (2010). The results of both refinements in terms of geometric parameters are the same within the threefold standard deviation.
Experimental
Single crystals of the title compound have been obtained during the study of the phase relationships in the ternary system Na2O—BaO—P2O5. They were synthesized in the solid state by reacting Na2CO3, BaCO3 and (NH4)2HPO4 in a platinum crucible. A mixture of these reagents taken in the molar ratio 1: 1: 2 was carefully ground in an agate mortar and successively heated at 373 K, 573 K and 773 K for 24 h at each temperature. After a new grinding, the reacting mixture was submitted to a final heat treatment at 973 K for 2 days followed by a slow cooling to room temperature at the rate of 5 K h-1. After an abundant washing of the batch with hot water, single crystals of the title compound could have been extracted.
Refinement
The highest residual peak in the final difference Fourier map was located 0.56 Å from atom Ba1 and the deepest hole was located 0.31 Å from atom Ba2.
Figures
Fig. 1.
Fig. 1.
View of the BaO9 polyhedra linkage in α-Ba2P2O7. Displacement ellipsoids are drawn at the 50% probability level. Symmetry codes: (i) x + 1/2, y, -z + 3/2; (ii) x + 1/2, -y + 1/2, -z + 3/2; (iii) -x, -y, -z + 1; (iv) x, -y + 1/2, z; (v) x, y + (more ...)
Fig. 2.
Fig. 2.
Projection of the α-Ba2P2O7 structure along [010] showing the connections between the P2O7 diphosphate groups and the three-dimensional framework of the BaO9 polyhedra.
Crystal data
Ba2P2O7F(000) = 792
Mr = 448.62Dx = 4.139 Mg m3
Orthorhombic, PnmaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2nCell parameters from 7790 reflections
a = 9.2875 (1) Åθ = 3.7–52.2°
b = 5.6139 (1) ŵ = 11.31 mm1
c = 13.8064 (1) ÅT = 296 K
V = 719.85 (2) Å3Hexagonal prism, colourless
Z = 40.26 × 0.14 × 0.14 mm
Data collection
Bruker APEXII CCD diffractometer4304 independent reflections
Radiation source: fine-focus sealed tube3726 reflections with I > 2σ(I)
graphiteRint = 0.028
Detector resolution: 8.3333 pixels mm-1θmax = 52.4°, θmin = 4.5°
ω and [var phi] scansh = −17→20
Absorption correction: multi-scan (SADABS; Bruker, 2008)k = −12→10
Tmin = 0.155, Tmax = 0.205l = −30→28
18034 measured reflections
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) + (0.0176P)2 + 0.4317P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.046(Δ/σ)max = 0.004
S = 1.07Δρmax = 1.59 e Å3
4304 reflectionsΔρmin = −1.99 e Å3
62 parametersExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.0075 (2)
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
Ba10.159652 (9)0.25000.744870 (6)0.00801 (2)
Ba20.138138 (9)0.25000.417071 (6)0.00841 (2)
P1−0.04603 (4)−0.25000.81569 (3)0.00724 (6)
P2−0.28072 (4)−0.25000.95778 (3)0.00722 (6)
O1−0.11642 (14)−0.25000.92264 (9)0.0129 (2)
O2−0.09496 (10)−0.0264 (2)0.76295 (7)0.01169 (13)
O3−0.35537 (10)−0.0271 (2)0.91982 (6)0.01215 (14)
O4−0.27382 (15)−0.25000.06760 (9)0.0130 (2)
O50.11429 (14)−0.25000.83242 (11)0.0160 (3)
Atomic displacement parameters (Å2)
U11U22U33U12U13U23
Ba10.00795 (3)0.00736 (4)0.00873 (3)0.000−0.00047 (2)0.000
Ba20.00856 (3)0.00891 (4)0.00776 (3)0.0000.00084 (2)0.000
P10.00544 (11)0.00757 (16)0.00873 (13)0.0000.00010 (9)0.000
P20.00839 (12)0.00706 (16)0.00622 (12)0.0000.00066 (9)0.000
O10.0088 (4)0.0198 (7)0.0100 (4)0.0000.0012 (3)0.000
O20.0126 (3)0.0091 (4)0.0133 (3)0.0008 (3)0.0005 (2)0.0022 (3)
O30.0145 (3)0.0101 (4)0.0119 (3)0.0029 (3)0.0000 (2)0.0022 (3)
O40.0161 (5)0.0160 (6)0.0069 (4)0.0000.0003 (3)0.000
O50.0061 (3)0.0243 (8)0.0176 (5)0.000−0.0008 (3)0.000
Geometric parameters (Å, °)
Ba1—O3i2.7585 (10)P1—O2xiii1.5208 (11)
Ba1—O3ii2.7585 (10)P1—O21.5208 (11)
Ba1—O2ii2.7591 (10)P1—O11.6148 (13)
Ba1—O2i2.7591 (10)P1—Ba2iii3.3255 (4)
Ba1—O4iii2.7978 (13)P2—O4xiv1.5175 (13)
Ba1—O22.8392 (10)P2—O3xiii1.5236 (11)
Ba1—O2iv2.8392 (10)P2—O31.5236 (11)
Ba1—O5v3.0850 (6)P2—O11.6012 (14)
Ba1—O53.0850 (6)P2—Ba2xv3.3668 (4)
Ba2—O5vi2.5794 (13)P2—Ba2xvi3.3812 (2)
Ba2—O3ii2.7377 (10)P2—Ba2xvii3.3812 (2)
Ba2—O3i2.7377 (10)O2—Ba1xvi2.7591 (10)
Ba2—O2iii2.8133 (10)O2—Ba2iii2.8133 (10)
Ba2—O2vii2.8133 (10)O3—Ba2xvi2.7377 (10)
Ba2—O3viii2.9094 (10)O3—Ba1xvi2.7585 (10)
Ba2—O3ix2.9094 (10)O3—Ba2xv2.9094 (10)
Ba2—O4x2.9313 (4)O4—P2xviii1.5175 (13)
Ba2—O4xi2.9313 (4)O4—Ba1iii2.7978 (13)
Ba2—P1iii3.3255 (4)O4—Ba2xix2.9313 (4)
Ba2—P2viii3.3668 (4)O4—Ba2xx2.9313 (4)
Ba2—P2xii3.3812 (2)O5—Ba2xxi2.5794 (13)
P1—O51.5067 (13)O5—Ba1xxii3.0850 (6)
O3i—Ba1—O3ii68.66 (5)O3ii—Ba2—O3ix76.39 (3)
O3i—Ba1—O2ii109.06 (3)O3i—Ba2—O3ix104.688 (19)
O3ii—Ba1—O2ii72.09 (3)O2iii—Ba2—O3ix94.29 (3)
O3i—Ba1—O2i72.09 (3)O2vii—Ba2—O3ix71.99 (3)
O3ii—Ba1—O2i109.06 (3)O3viii—Ba2—O3ix50.95 (4)
O2ii—Ba1—O2i68.43 (4)O5vi—Ba2—O4x77.53 (3)
O3i—Ba1—O4iii141.44 (2)O3ii—Ba2—O4x52.44 (3)
O3ii—Ba1—O4iii141.44 (3)O3i—Ba2—O4x118.59 (3)
O2ii—Ba1—O4iii73.93 (3)O2iii—Ba2—O4x122.07 (3)
O2i—Ba1—O4iii73.93 (3)O2vii—Ba2—O4x71.11 (3)
O3i—Ba1—O273.87 (3)O3viii—Ba2—O4x131.51 (3)
O3ii—Ba1—O2109.79 (3)O3ix—Ba2—O4x80.73 (3)
O2ii—Ba1—O2177.035 (6)O5vi—Ba2—O4xi77.53 (3)
O2i—Ba1—O2112.59 (4)O3ii—Ba2—O4xi118.59 (3)
O4iii—Ba1—O2103.55 (3)O3i—Ba2—O4xi52.44 (3)
O3i—Ba1—O2iv109.79 (3)O2iii—Ba2—O4xi71.11 (3)
O3ii—Ba1—O2iv73.87 (3)O2vii—Ba2—O4xi122.07 (3)
O2ii—Ba1—O2iv112.59 (4)O3viii—Ba2—O4xi80.73 (3)
O2i—Ba1—O2iv177.035 (6)O3ix—Ba2—O4xi131.51 (3)
O4iii—Ba1—O2iv103.55 (3)O4x—Ba2—O4xi146.51 (5)
O2—Ba1—O2iv66.25 (4)O5—P1—O2xiii111.63 (5)
O3i—Ba1—O5v146.01 (3)O5—P1—O2111.63 (5)
O3ii—Ba1—O5v78.63 (3)O2xiii—P1—O2111.29 (8)
O2ii—Ba1—O5v67.45 (3)O5—P1—O1105.06 (8)
O2i—Ba1—O5v129.77 (3)O2xiii—P1—O1108.47 (5)
O4iii—Ba1—O5v71.89 (3)O2—P1—O1108.47 (5)
O2—Ba1—O5v110.43 (3)P2—O1—P1131.52 (9)
O2iv—Ba1—O5v49.81 (3)P1—O2—Ba1xvi136.86 (5)
O3i—Ba1—O578.63 (3)P1—O2—Ba2iii95.57 (5)
O3ii—Ba1—O5146.01 (3)Ba1xvi—O2—Ba2iii95.66 (3)
O2ii—Ba1—O5129.77 (3)P1—O2—Ba1104.14 (5)
O2i—Ba1—O567.45 (3)Ba1xvi—O2—Ba1112.16 (4)
O4iii—Ba1—O571.89 (3)Ba2iii—O2—Ba1106.55 (3)
O2—Ba1—O549.81 (3)P2—O3—Ba2xvi101.17 (4)
O2iv—Ba1—O5110.43 (3)P2—O3—Ba1xvi136.36 (5)
O5v—Ba1—O5130.97 (5)Ba2xvi—O3—Ba1xvi111.02 (4)
O5vi—Ba2—O3ii110.68 (3)P2—O3—Ba2xv93.55 (5)
O5vi—Ba2—O3i110.68 (3)Ba2xvi—O3—Ba2xv103.61 (3)
O3ii—Ba2—O3i69.25 (4)Ba1xvi—O3—Ba2xv106.11 (3)
O5vi—Ba2—O2iii74.14 (3)P2xviii—O4—Ba1iii160.15 (8)
O3ii—Ba2—O2iii169.56 (3)P2xviii—O4—Ba2xix93.46 (3)
O3i—Ba2—O2iii118.44 (3)Ba1iii—O4—Ba2xix92.23 (3)
O5vi—Ba2—O2vii74.14 (3)P2xviii—O4—Ba2xx93.46 (3)
O3ii—Ba2—O2vii118.44 (3)Ba1iii—O4—Ba2xx92.23 (3)
O3i—Ba2—O2vii169.56 (3)Ba2xix—O4—Ba2xx146.51 (5)
O2iii—Ba2—O2vii53.01 (4)P1—O5—Ba2xxi161.87 (9)
O5vi—Ba2—O3viii144.15 (3)P1—O5—Ba1xxii94.30 (3)
O3ii—Ba2—O3viii104.688 (19)Ba2xxi—O5—Ba1xxii93.20 (3)
O3i—Ba2—O3viii76.39 (3)P1—O5—Ba194.30 (3)
O2iii—Ba2—O3viii71.99 (3)Ba2xxi—O5—Ba193.20 (3)
O2vii—Ba2—O3viii94.29 (3)Ba1xxii—O5—Ba1130.97 (5)
O5vi—Ba2—O3ix144.15 (3)
Symmetry codes: (i) x+1/2, y, −z+3/2; (ii) x+1/2, −y+1/2, −z+3/2; (iii) −x, −y, −z+1; (iv) x, −y+1/2, z; (v) x, y+1, z; (vi) −x+1/2, −y, z−1/2; (vii) −x, y+1/2, −z+1; (viii) −x−1/2, −y, z−1/2; (ix) −x−1/2, y+1/2, z−1/2; (x) x+1/2, y+1, −z+1/2; (xi) x+1/2, y, −z+1/2; (xii) x+1/2, y+1, −z+3/2; (xiii) x, −y−1/2, z; (xiv) x, y, z+1; (xv) −x−1/2, −y, z+1/2; (xvi) x−1/2, y, −z+3/2; (xvii) x−1/2, y−1, −z+3/2; (xviii) x, y, z−1; (xix) x−1/2, y−1, −z+1/2; (xx) x−1/2, y, −z+1/2; (xxi) −x+1/2, −y, z+1/2; (xxii) x, y−1, z.
Footnotes
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: WM2413).
  • Barbier, J. & Echard, J.-P. (1998). Acta Cryst. C54, IUC9800070.
  • Bian, J., Kim, D. W. & Hong, K. S. (2004). Jpn. J. Appl. Phys. Part 1, 43, 3521–3525.
  • Brandenburg, K. (1999). DIAMOND Crystal Impact GbR, Bonn, Germany.
  • Bruker (2008). SADABS, APEX2 and SAINT Bruker AXS Inc., Madison, Wisconsin, USA.
  • Durif, A. (1995). Crystal Chemistry of Condensed Phosphates New York, London: Plenum Press.
  • ElBelghitti, A. A., Elmarzouki, A., Boukhari, A. & Holt, E. M. (1995). Acta Cryst. C51, 1478–1480.
  • Elmarzouki, A., Boukhari, A., Holt, E. M. & Berrada, A. (1995). J. Alloys Compd.227, 125–130.
  • Farrugia, L. J. (1997). J. Appl. Cryst.30, 565.
  • Grenier, J. C. & Masse, R. (1977). Bull. Soc. Fr. Miner. Cristallogr.92, 91–92.
  • Hagman, L. O., Jansson, I. & Magneli, C. (1968). Acta Chem. Scand.22, 1419–1429.
  • Heyward, C., Mann, M. & Kolis, J. (2010). Acta Cryst. E66 In the press.
  • Kokhanovskii, V. (2004). Zh. Neorg. Khim.49, 511–517.
  • McCauley, R. A. & Hummel, F. A. (1968). Trans. Br. Ceram. Soc 67, 619–628.
  • Mehdi, S., Raza Hussain, M. & Rama Rao, B. (1977). Indian J. Chem. Sect. A, 15, 820-821.
  • Pang, R., Li, C., Shi, L. & Su, Q. (2009). J. Phys. Chem. Solids, 70, 303–306.
  • Peng, M., Sprenger, B., Schmidt, A., Schwefel, H. G. L. & Wondraczek, L. (2010). Opt. Express, 18, 12852–12863. [PubMed]
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of
International Union of Crystallography