(IUCr) The iron phosphate NaBaFe2(PO4)3

Volume 64
Part 8
Page i51
August 2008

Received 27 May 2008
Accepted 22 July 2008
Online 31 July 2008

Key indicators
Single-crystal X-ray study
T = 293 K
Mean (Fe-O) = 0.005 Å
Disorder in main residue
R = 0.025
wR = 0.060
Data-to-parameter ratio = 9.4
Details

The iron phosphate NaBaFe₂(PO₄)₃

Mourad Hidouri,^a ^* Hasna Jerbi ^a and Mongi Ben Amara ^a

^aFaculté des Sciences de Monastir, 5019 Monastir, Tunisia
Correspondence e-mail: mourad_hidouri@yahoo.fr

A new iron phosphate, sodium barium diiron tris(phosphate), NaBaFe₂(PO₄)₃, has been synthesized by the flux method and shown to exhibit the well known langbeinite type structure. The Na, Ba and Fe atoms all lie on threefold axes, while the P and O atoms occupy general positions, one of the O atoms being disordered over two positions, with site occupancy factors of ca 0.7 and 0.3. The [Fe₂(PO₄)₃] framework consists of FeO₆ octahedra sharing all their corners with the PO₄ tetrahedra. The Na⁺ and Ba²⁺ cations are almost equally distributed over two distinct cavities, in which they occupy slightly different positions.

Related literature

For related literature, see: Baur (1974); Moffat (1978); Padhi et al. (1997); Shannon (1976). For the structure of langbeinite, see Zemann & Zemann (1957); Battle et al. (1986, 1988).

Experimental

Crystal data

NaBaFe₂(PO₄)₃
M_r = 556.94
Cubic, P 2₁ 3
a = 9.796 (1) Å
V = 940.1 (3) Å³
Z = 4
Mo K radiation
= 7.82 mm^-1
T = 293 (2) K
0.1 × 0.1 × 0.1 mm

Data collection

Enraf-Nonius CAD4 diffractometer
Absorption correction: scan (North et al., 1968) T_min = 0.35, T_max = 0.46
2114 measured reflections
657 independent reflections
644 reflections with I > 2(I)
R_int = 0.082
2 standard reflections frequency: 120 min intensity decay: 1%

Refinement

R[F² > 2(F²)] = 0.025
wR(F²) = 0.059
S = 0.92
657 reflections
70 parameters
4 restraints
_max = 0.57 e Å^-3
_min = -0.49 e Å^-3
Absolute structure: Flack (1983), 123 Friedel pairs
Flack parameter: -0.03 (3)

Table 1
Selected bond angles (°)

O4Bⁱ-Fe2-O1ⁱⁱ	89.8 (8)
O3-P-O4A	115.1 (3)
Symmetry codes: (i) z, x, y; (ii) $[-z+{\script{3\over 2}}, -x+1, y-{\script{1\over 2}}]$ .

Data collection: CAD-4 EXPRESS (Enraf-Nonius, 1994); cell refinement: CAD-4 EXPRESS; 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, 1998); software used to prepare material for publication: SHELXL97.

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BR2076 ).

References

Battle, P. D., Cheetham, A. K., Harrison, W. T. A. & Long, G. J. (1986). J. Solid State Chem. 62, 16-25.
Battle, P. D., Gibb, T. C., Nixon, S. & Harrison, W. T. A. (1988). J. Solid State Chem. 75, 21-29.
Baur, W. H. (1974). Acta Cryst. B30, 1195-1215.
Brandenburg, K. (1998). DIAMOND. University of Bonn, Germany.
Enraf-Nonius (1994). CAD-4 EXPRESS. Enraf-Nonius, Delft, The Netherlands.
Flack, H. D. (1983). Acta Cryst. A39, 876-881.
Harms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany.
Moffat, J. B. (1978). Catal. Rev. Sci. Eng. 18, 199-258.
North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351-359.
Padhi, A., Nanjundaswamy, K. & Goodenough, J. (1997). J. Electrochem. Soc. 144, 1188-1194.
Shannon, R. D. (1976). Acta Cryst. A32, 751-767.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.
Zemann, A. & Zemann, J. (1957). Acta Cryst. 10, 409-413.

inorganic compounds

The iron phosphate NaBaFe2(PO4)3